CN108330367B - Absorbable orthopedic implant magnesium alloy and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of biomedical materials, in particular to an absorbable orthopedic implanted magnesium alloy, which is composed of the following components in mass percentage: 4.0-8.0% Zn, 0.8-2.0% Y, 0.6-2.0% Nd, 0.2~0.4% Sc, the balance is Mg. The invention also discloses a preparation method of the magnesium alloy: using magnesium ingot, zinc ingot, Mg-Y master alloy, Mg-Nd master alloy and Mg-Sc master alloy as charge for melting. In the present invention, a relatively high content of Zn is added to pure magnesium as a main strengthening element, and the high requirements on the strength of orthopaedic implant materials are achieved through solid solution strengthening and dispersion strengthening, and a small amount of rare earth elements Y, Nd and Sc are compounded to improve the alloy. The mechanical properties and corrosion resistance properties, and to achieve the purpose of refining the structure and grain. Through multi-pass, large extrusion ratio extrusion processing, combined with annealing heat treatment after extrusion, a magnesium alloy with ultra-fine grains and the second item is finely dispersed in the matrix, thereby greatly improving its mechanical properties. performance and corrosion resistance.

Description

A kind of absorbable orthopedic implant magnesium alloy and preparation method thereof

technical field

The invention belongs to the field of biomedical materials, in particular to an absorbable orthopedic implanted magnesium alloy and a preparation method thereof.

Background technique

Bone tissue damage caused by traffic accidents, sports trauma and other reasons has a high incidence in people's daily life. During the treatment of bone tissue damage, implanted devices are required to repair and fix the bone tissue. Therefore, orthopedic implanted devices Become the most important one in the medical device industry. At present, the widely used orthopedic implant device materials in clinic mainly include metal biological materials such as stainless steel, titanium alloy and cobalt alloy. However, these metal biomaterials have the following disadvantages: First, the elastic modulus of the implanted device does not match the bone tissue, and after implantation, a "stress shielding" effect occurs at the connection with the bone tissue, thereby inhibiting the growth of new bone and reducing bone growth. Second, as an inert metal, it will remain in the body as a foreign body for a long time after implantation, resulting in ion dissolution and affecting human health. Therefore, a second operation is required to remove it, which increases the pain of the patient. Since the beginning of the 21st century, a new generation of medical metal materials with biodegradable properties, represented by magnesium alloys, has attracted people's attention. The advantage of magnesium alloy is that its density and elastic modulus are close to human bone, which can effectively alleviate the adverse effect of "stress shielding" effect on bone growth; and magnesium alloy can be gradually degraded in the human body, thus avoiding secondary surgery. The main degradation product Mg ^{2+ is} not only not toxic to the human body, but also has the property of promoting the proliferation of osteoblasts. Therefore, magnesium alloys have great application prospects as an absorbable orthopaedic implant material.

At present, the main researches on magnesium alloys as orthopaedic implant materials include: Lambotte first applied metal magnesium bone plates to fix lower extremity fractures in 1907. After 8 days, the bone plates degraded and a large amount of gas was generated under the skin. Troitskii and Znamenski reported the use of Mg-Ca and Mg-Al alloys to treat fractures in 1944 and 1945, respectively. All of these reports indicated that no systemic toxicity and local inflammatory reactions occurred when magnesium and magnesium alloys were used as internal fixators. However, the degradation rate of magnesium and magnesium alloys in the body is too fast, so that the internal fixation cannot maintain mechanical integrity before bone healing, resulting in fixation failure. In addition, a large amount of hydrogen generated during the rapid degradation of magnesium and magnesium alloys can cause subcutaneous emphysema. Therefore, the application of magnesium alloys in orthopedic implant devices is severely limited. With the continuous development of alloy smelting and processing technology, different series of magnesium alloys such as Mg-Zn series, Mg-Re series, Mg-Al series Mg-Zn-RE series, etc. have been successfully developed. Compared with the early magnesium and magnesium alloys , its degradation rate has been greatly reduced, which provides conditions for the application of magnesium alloys in orthopedic implant devices. In 2006, Witte et al. implanted two Mg-Al magnesium alloys AZ31 and AZ91, and two rare earth magnesium alloys WE43 and LAE442, respectively, into the femoral medullary cavity of guinea pigs. After 18 weeks, more new bone was formed around the magnesium alloy. The study by Duygulu et al. who implanted AZ31 magnesium alloy bone nails into the hip bone of goats for 3 months showed that the magnesium alloy bone nails were significantly degraded, and new bone was generated at the interface between magnesium alloy and bone tissue. Zhang Guangdao et al. implanted AZ31 magnesium alloy into the mandible of rabbits. After 2 weeks, callus formed around the implant; after 8 weeks, mature bone tissue was formed, and no negative effects on animal circulation, immunity and urinary system were found. Zhang et al. implanted a Mg-Zn alloy rod with a diameter of 4.5 mm and a length of 10 mm into the femur of New Zealand white rabbits, and detected the electrolytes of the liver and kidney function of the rabbits. In the pathological sections of the spleen and femur, the study showed that the magnesium alloy gradually degraded and produced air bubbles around it. There was no obvious abnormality in the pathological sections of the liver and kidney, and new bone was formed around the femur, indicating that the magnesium alloy as a degradable bone fixation material has good performance. biocompatibility and mechanical properties.

The study of magnesium alloy as an orthopaedic implant material in animals has confirmed the feasibility of its application in absorbable orthopaedic implant devices, but its mechanical properties, corrosion resistance and biocompatibility still need further research to improve.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an absorbable orthopaedic implantable magnesium alloy with good mechanical properties, corrosion resistance and cell compatibility.

Another object of the present invention is to provide a preparation method of the magnesium alloy.

To achieve one of the above objects, the present invention adopts the following technical solutions:

An absorbable orthopaedic implantable magnesium alloy is composed of the following components by mass percentage: 4.0-8.0% Zn, 0.8-2.0% Y, 0.6-2.0% Nd, 0.2-0.4% Sc, and the balance is Mg.

Further, it is composed of the following components by mass percentage: 4.0% Zn, 1.2% Y, 0.8% Nd, 0.2% Sc and 93.8% Mg.

A preparation method of the above-mentioned magnesium alloy is made by using magnesium ingot, zinc ingot, Mg-Y master alloy, Mg-Nd master alloy and Mg-Sc master alloy as charging materials.

Further, the addition amount of Zn, Y, Nd and Sc in the charge is 1.1-1.25 times of the content in the magnesium alloy.

Further, the purity of the magnesium ingot and the zinc ingot are both ≥99.9%, the Mg-Y master alloy is a master alloy containing 25.0wt% Y, and the Mg-Nd master alloy is a master alloy containing 25.0wt% Nd , the Mg-Sc master alloy is a master alloy containing 10.0wt% Sc.

Further, the preparation method comprises the following steps:

S1, put the crucible into the furnace and heat, after the furnace temperature rises to 400～600 ℃, feed carbon dioxide and sulfur hexafluoride gas mixture into the furnace;

S2, after passing the mixed gas for 10~15min, add a magnesium ingot, the crucible is heated to 700~800 DEG C, after the magnesium ingot is completely melted, add the Mg-Sc master alloy, be warming up to 800~850 DEG C, and keep the temperature for 60~120min, Then add Mg-Y master alloy and Mg-Nd master alloy, reduce the furnace temperature to 700~800 ° C, after heat preservation for 8~12min, add zinc ingot, after heat preservation for 20~30min, uniformly stir the melt for 5~10min, Finally, carry out slag removal, pouring and demoulding to obtain intermediate products;

S3. Perform solid solution treatment on the intermediate product, and perform one extrusion after solid solution to obtain an extruded product;

S4, performing solid solution treatment on the primary extruded product, and performing secondary extrusion after solid solution to obtain a magnesium alloy.

Further, the volume ratio of carbon dioxide and sulfur hexafluoride is 100:1.

Further, the furnace is a resistance furnace.

Further, in described S3, the condition of solution treatment is: solution temperature is 460～530 ℃, and solution time is 1～4h; The condition of described one extrusion is: extrusion temperature 450～480 ℃ , the extrusion ratio is 5~10, the extrusion rate is 2~4m/min, and the heating temperature of the die during extrusion is 430~470°C.

Further, in described S4, the condition of solution treatment is: solution temperature is 460～530 ℃, and solution time is 2～6h; The condition of described secondary extrusion is: extrusion temperature is 380～420 ℃ C, the extrusion ratio is 10~15, the extrusion rate is 2~4m/min, and the heating temperature of the die during extrusion is 360~430°C.

Compared with the existing absorbable orthopaedic implanted magnesium alloy materials, the beneficial effects of the magnesium alloy of the present invention are:

1. The content of Zn is high. The purpose of high Zn element addition is to achieve solid solution strengthening through the solid solution of Zn in Mg, and realize dispersion strengthening through the precipitation of a large amount of Zn-containing strengthening phase, thereby greatly improving the strength of magnesium alloys and achieving orthopedic implantation. The material has high requirements for strength. At the same time, Zn is an essential element for human body structure, catalysis and regulation functions, so magnesium alloys with high Zn content have good biocompatibility.

2. The mechanical properties and corrosion resistance of magnesium alloys are further improved by the compound addition of a small amount of rare earth elements Y, Nd and Sc. Y and Nd are rare earth elements often added in magnesium alloys, which can effectively reduce the degradation rate of magnesium alloys. Compared with other rare earth elements, Sc not only has the characteristics of high melting point and low density, it can promote the nucleation of magnesium alloys during solidification, thereby achieving grain refinement, and its diffusion rate in magnesium alloys is very low, so , has a more obvious strengthening effect on magnesium alloys. In addition, the maximum solid solubility of Sc in the Mg matrix can reach 15%, which is much higher than that of other rare earth elements, so it can also play a solid solution strengthening effect to a certain extent. Moreover, the magnesium alloy of the present invention has a low total rare earth content, which can minimize the potential risk of rare earth elements to the human body, thereby improving the overall biocompatibility of the alloy.

3. Using the two-pass extrusion process, the average grain size of the magnesium alloy can be controlled at 0.5~2μm, and the purpose of improving the strength and shaping at the same time is achieved through grain refinement. In addition, the MgZnY strengthening phase in the magnesium alloy can be greatly refined by two-pass extrusion, so that the MgZnY strengthening phase is dispersed and uniformly distributed in the intragranular and grain boundary regions of the magnesium alloy, which can not only play a strengthening role, but also can The galvanic cell formed during the degradation of the magnesium alloy is made smaller, the uniformity of the degradation of the magnesium alloy is improved, and the overall degradation rate of the magnesium alloy is reduced.

4. The present invention prepares an absorbable orthopaedic implant Mg-Zn-Y-Nd-Sc alloy by adding a small amount of rare earth elements Y, Nd and Sc to the Mg-Zn alloy, and refines the alloy by using a two-pass extrusion method. The grains and strengthening phase of the alloy are improved to improve its mechanical properties, so that the tensile strength reaches 325MPa, the yield strength reaches 306MPa, and the elongation reaches 18%.

Description of drawings

Fig. 1 is the room temperature tensile property diagram of the magnesium alloy obtained in Example 4;

Fig. 2 is the microstructure SEM figure and EDS composition analysis figure of the magnesium alloy obtained in Example 4;

Fig. 3 is the room temperature tensile fracture topography of the magnesium alloy obtained in Example 4;

Fig. 4 is the electrochemical corrosion test curve diagram of the magnesium alloy obtained in Example 4;

Figure 5 is a cell activity diagram after 48h of human umbilical vein endothelial cells are cultured in extracts with concentrations of 10%, 50%, and 100% prepared from the magnesium alloy obtained in Example 4;

Figure 6 is a graph of cell morphology after culturing human umbilical vein endothelial cells for 48h with extracts prepared from the magnesium alloy obtained in Example 4 with concentrations of 10%, 50% and 100%;

FIG. 7 is a graph showing the room temperature tensile properties of the magnesium alloys obtained in Example 4 and Example 6. FIG.

Detailed ways

The present invention will be further described below with reference to specific embodiments.

Example 1

Absorbable orthopaedic implant magnesium alloy, the composition is: 4.0wt% Zn, 1.2wt% Y, 0.8wt% Nd, 0.2wt% Sc, the balance is Mg, and unavoidable impurity elements.

1. Preliminary preparation

The raw materials of this embodiment are:

High-purity magnesium ingot (purity ≥99.9%): 2520g

High-purity zinc ingot (purity ≥99.9%): 144g, in which the content of Zn is 1.2 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Y master alloy: 158g, wherein the content of Y is 1.1 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Nd master alloy: 106g, wherein the content of Nd is 1.1 times that in the obtained magnesium alloy (target product);

Mg-10.0wt% Sc master alloy: 72g, wherein the content of Sc is 1.2 times that in the obtained magnesium alloy (target product);

In order to avoid the oxidation and combustion of the magnesium alloy, there is always a protective gas in the furnace during the whole smelting process. The protective gas used in this embodiment is a mixed gas of carbon dioxide and sulfur hexafluoride, and the volume ratio of carbon dioxide and sulfur hexafluoride is 100:1.

2. Preparation of intermediate products

a. Heat the crucible, the slag removal tool, the stirring rod and the mold to 120°C, then take it out, apply a thin and uniform coating on the surface, and put it into an oven for drying;

B, put the processed crucible into the resistance furnace, set the furnace temperature to 400 ° C, when the furnace temperature rises to the set temperature, feed carbon dioxide and sulfur hexafluoride gas mixture;

c, after 10min of mixed gas, add high-purity magnesium ingot, and furnace temperature is raised to 700 ℃ simultaneously;

d, at 700 DEG C, be incubated until after the magnesium ingot is completely melted, add the Mg-Sc master alloy, and the furnace temperature is raised to 800 DEG C, and is incubated for 60min;

e. After the heat preservation, add Mg-Y master alloy and Mg-Nd master alloy, and reduce the furnace temperature to 700°C;

f, after being incubated at 700 DEG C for 8min, add zinc ingot;

g. After 20min of heat preservation, the melt is stirred at a constant speed for 5min, then slag is removed, and it is left to stand for 10min;

h. The melt is poured into the mold, and the mold is demolded to obtain an ordinary solidified state Mg-4.0wt% Zn-1.2wt% Y-0.8wt%Nd-0.2wt%Sc alloy (intermediate product).

3. Preparation of extruded alloy samples

a. The prepared ordinary solidified state Mg-4.0wt% Zn-1.2wt% Y-0.8wt% Nd-0.2wt% Sc alloy (intermediate product) is subjected to solution treatment, and the solution temperature is 460 ° C. The time is 2h;

b, carry out an extrusion after the solid solution, the extrusion temperature is 450°C, the extrusion ratio is 7, the extrusion rate is 2m/min, and the heating temperature of the die in the extrusion process is 430°C, and an extrusion can be obtained once state product;

c, carry out solution treatment to the first extruded product, the solution temperature is 460 ° C, and the solution time is 4h; after the solution, the secondary extrusion is carried out, the extrusion temperature is 400 ° C, and the extrusion ratio is 12, and the extrusion ratio is 12. The speed was 2m/min, and the heating temperature of the die during extrusion was 360°C to obtain the final product.

Example 2

Absorbable orthopaedic implant magnesium alloy, the composition is: 6.0wt% Zn, 1.2wt% Y, 0.8wt% Nd, 0.2wt% Sc, the balance is Mg, and unavoidable impurity elements.

1. Preliminary preparation

The raw materials required for this example are:

High-purity magnesium ingot (purity ≥99.9%): 1632g

High-purity zinc ingot (purity ≥99.9%): 144g, in which the content of Zn is 1.2 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Y master alloy: 106g, wherein the content of Y is 1.1 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Nd master alloy: 70g, wherein the content of Nd is 1.1 times that in the obtained magnesium alloy (target product);

Mg-10.0wt% Sc master alloy: 48g, wherein the content of Sc is 1.2 times that in the obtained magnesium alloy (target product);

In order to avoid the oxidation and combustion of the magnesium alloy, there is always a protective gas in the furnace during the whole smelting process. The protective gas used in this embodiment is a mixture of carbon dioxide and sulfur hexafluoride, and the volume ratio of carbon dioxide and sulfur hexafluoride is 100. :1.

2. Preparation of intermediate products

a. Heat the crucible, the slag removal tool, the stirring rod and the mold to 130°C, then take it out, brush a thin and uniform coating on the surface, and put it into an oven for drying;

B, put the processed crucible into the resistance furnace, set the furnace temperature to 500 ° C, when the furnace temperature rises to the set temperature, feed carbon dioxide and sulfur hexafluoride gas mixture;

c, after 12min of passing mixed gas, add high-purity magnesium ingot, and furnace temperature is raised to 750 ℃ simultaneously;

d, at 750 DEG C, be incubated until the magnesium ingot is completely melted, add the Mg-Sc master alloy, and the furnace temperature is raised to 820 DEG C, and is incubated for 80min;

e. After the heat preservation, add Mg-Y master alloy and Mg-Nd master alloy, and reduce the furnace temperature to 750°C;

f, after insulation 10min at 750 DEG C, add zinc ingot;

g. After 30min of heat preservation, the melt is stirred at a constant speed for 10min, then slag is removed, and it is left to stand for 15min;

h. The melt is poured into the mold, and the mold is demolded to obtain an ordinary solidified state Mg-6.0wt% Zn-1.2wt% Y-0.8wt%Nd-0.2wt%Sc alloy (intermediate product).

3. Preparation of extruded alloy samples

a. The prepared ordinary solidified state Mg-6.0wt% Zn-1.2wt% Y-0.8wt% Nd-0.2wt% Sc alloy (intermediate product) is subjected to solution treatment, and the solution temperature is 480 ° C. The time is 2h;

b, carry out an extrusion after the solid solution, the extrusion temperature is 480°C, the extrusion ratio is 7, the extrusion rate is 2m/min, and the heating temperature of the die in the extrusion process is 450°C, and an extrusion can be obtained. state product;

c, carry out solution treatment to the one-time extruded product, the solution temperature is 480 ° C, and the solution time is 4h; after the solid solution, the secondary extrusion is carried out, the extrusion temperature is 420 ° C, and the extrusion ratio is 12, and the extrusion ratio is 12. The speed was 2m/min, and the heating temperature of the die during extrusion was 380°C to obtain the final product.

Example 3

Absorbable orthopaedic implant magnesium alloy, the composition is: 8.0wt% Zn, 2.0wt% Y, 0.8wt% Nd, 0.4wt% Sc, the balance is Mg, and unavoidable impurity elements.

1. Preliminary preparation

The raw materials required for this example are:

High-purity magnesium ingot (purity ≥99.9%): 1466g

High-purity zinc ingot (purity ≥99.9%): 192g, in which the content of Zn is 1.2 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Y master alloy: 176g, wherein the content of Y is 1.1 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Nd master alloy: 70g, wherein the content of Nd is 1.1 times that in the obtained magnesium alloy (target product);

Mg-10.0wt% Sc master alloy: 96g, wherein the content of Sc is 1.2 times that in the obtained magnesium alloy (target product);

In order to avoid the oxidation and combustion of the magnesium alloy, there is always a protective gas in the furnace during the whole smelting process. The protective gas used in this embodiment is a mixture of carbon dioxide and sulfur hexafluoride, and the volume ratio of carbon dioxide and sulfur hexafluoride is 100. :1.

2. Preparation of intermediate products

a. Heat the crucible, the slag removal tool, the stirring rod and the mold to 150°C, then take it out, brush a thin and uniform coating on the surface, and put it into an oven for drying;

b, put the processed crucible into the resistance furnace, set the furnace temperature to 600 ° C, when the furnace temperature rises to the set temperature, feed carbon dioxide and sulfur hexafluoride gas mixture;

c, after 12min of passing mixed gas, add high-purity magnesium ingot, and furnace temperature is raised to 800 ℃ simultaneously;

D, at 800 DEG C, after being kept warm until the magnesium ingot is completely melted, add Mg-Sc master alloy, and the furnace temperature is raised to 850 DEG C, kept for 100min;

e. After the heat preservation, add Mg-Y master alloy and Mg-Nd master alloy, and reduce the furnace temperature to 800°C;

f, after being incubated 12min at 800 DEG C, add zinc ingot;

g. After 30min of heat preservation, the melt is stirred at a constant speed for 10min, then slag is removed, and it is left to stand for 15min;

h. The melt is poured into a mold and demolded to obtain an ordinary solidified Mg-8.0wt% Zn-1.2wt% Y-0.8wt%Nd-0.4wt%Sc alloy (intermediate product).

3. Preparation of extruded alloy samples

a. The prepared ordinary solidified state Mg-8.0wt% Zn-1.2wt% Y-0.8wt% Nd-0.4wt% Sc alloy (intermediate product) is subjected to solution treatment, and the solution temperature is 530 ° C. The time is 2h;

b, carry out an extrusion after the solid solution, the extrusion temperature is 480 ° C, the extrusion ratio is 5, the extrusion rate is 2 m/min, and the heating temperature of the die in the extrusion process is 470 ° C, and an extrusion can be obtained once state product;

c, carry out solution treatment to the one-time extruded product, the solution temperature is 530 ° C, and the solution time is 6h; after the solid solution, the secondary extrusion is carried out, the extrusion temperature is 420 ° C, and the extrusion ratio is 15, and the extrusion ratio is 15. The speed was 2m/min, and the heating temperature of the die during extrusion was 400°C to obtain the final product.

Example 4

Absorbable orthopaedic implant magnesium alloy, the composition is: 4.0wt% Zn, 0.8wt% Y, 0.6wt% Nd, 0.2wt% Sc, the balance is Mg, and inevitable impurity elements.

1. Preliminary preparation

The raw materials required for this example are:

High-purity magnesium ingot (purity ≥99.9%): 2599g

High-purity zinc ingot (purity ≥99.9%): 144g, in which the content of Zn is 1.2 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Y master alloy: 106g, wherein the content of Y is 1.1 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Nd master alloy: 79g, wherein the content of Nd is 1.1 times that in the obtained magnesium alloy (target product);

Mg-10.0wt% Sc master alloy: 72g, wherein the content of Sc is 1.2 times that in the obtained magnesium alloy (target product);

In order to avoid the oxidation and combustion of the magnesium alloy, there is always a protective gas in the furnace during the whole smelting process. The protective gas used in this embodiment is a mixture of carbon dioxide and sulfur hexafluoride, and the volume ratio of carbon dioxide and sulfur hexafluoride is 100. :1.

2. Preparation of intermediate products

a. Heat the crucible, the slag removal tool, the stirring rod and the mold to 120°C, then take it out, brush a thin and uniform coating on the surface, and put it into an oven for drying;

b, put the processed crucible into the resistance furnace, set the furnace temperature to 400 ° C, when the furnace temperature rises to the set temperature, feed carbon dioxide and sulfur hexafluoride gas mixture;

c, after 10min of mixed gas, add high-purity magnesium ingot, and furnace temperature is raised to 700 ℃ simultaneously;

D, at 700 DEG C, after being kept warm until the magnesium ingot is completely melted, add Mg-Sc master alloy, and the furnace temperature is raised to 800 DEG C, and keep warm for 60min;

e. After the heat preservation, add Mg-Y master alloy and Mg-Nd master alloy, and reduce the furnace temperature to 700°C;

f, after insulation 10min at 700 DEG C, add zinc ingot;

g. After 20min of heat preservation, the melt is stirred at a constant speed for 5min, then slag is removed, and it is left to stand for 15min;

h. The melt is poured into the mold, and the mold is demolded to obtain an ordinary solidified Mg-4.0wt% Zn-0.8wt%Y-0.6wt%Nd-0.2wt%Sc alloy (intermediate product).

3. Preparation of extruded alloy samples

a. The prepared ordinary solidified state Mg-4.0wt% Zn-0.8wt%Y-0.6wt%Nd-0.2wt%Sc alloy (intermediate product) is subjected to solution treatment, and the solution temperature is 460 ° C. The time is 1h;

b, carry out an extrusion after the solid solution, the extrusion temperature is 450°C, the extrusion ratio is 7, the extrusion rate is 4m/min, and the heating temperature of the die in the extrusion process is 430°C, and an extrusion can be obtained. state product;

c, carry out solution treatment to the one-time extruded product, the solution temperature is 460 ° C, and the solution time is 2h; after the solid solution, carry out secondary extrusion, the extrusion temperature is 380 ° C, and the extrusion ratio is 12, and the extrusion ratio is 12. The speed was 2m/min, and the heating temperature of the die during extrusion was 360°C to obtain the final product.

Example 5

Absorbable orthopaedic implant magnesium alloy, the composition is: 6.0wt% Zn, 1.2wt% Y, 2.0wt% Nd, 0.3wt% Sc, the balance is Mg, and unavoidable impurity elements.

1. Preliminary preparation

The raw materials required for this example are:

High-purity magnesium ingot (purity ≥99.9%): 1486g

High-purity zinc ingot (purity ≥99.9%): 144g, in which the content of Zn is 1.2 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Y master alloy: 106g, wherein the content of Y is 1.1 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Nd master alloy: 192g, in which the content of Nd is 1.1 times that in the obtained magnesium alloy (target product);

Mg-10.0wt% Sc master alloy: 72g, wherein the content of Sc is 1.2 times that in the obtained magnesium alloy (target product);

In order to avoid the oxidation and combustion of the magnesium alloy, there is always a protective gas in the furnace during the whole smelting process. The protective gas used in this embodiment is a mixture of carbon dioxide and sulfur hexafluoride, and the volume ratio of carbon dioxide and sulfur hexafluoride is 100. :1.

2. Preparation of intermediate products

a. Heat the crucible, the slag removal tool, the stirring rod and the mold to 130°C, then take it out, brush a thin and uniform coating on the surface, and put it into an oven for drying;

B, put the processed crucible into the resistance furnace, set the furnace temperature to 500 ° C, when the furnace temperature rises to the set temperature, feed carbon dioxide and sulfur hexafluoride gas mixture;

c, after 15min of passing mixed gas, add high-purity magnesium ingot, and furnace temperature is raised to 750 ℃ simultaneously;

d, at 750 DEG C, be incubated until the magnesium ingot is completely melted, add the Mg-Sc master alloy, and the furnace temperature is raised to 850 DEG C, and is incubated for 120min;

e. After the heat preservation, add Mg-Y master alloy and Mg-Nd master alloy, and reduce the furnace temperature to 750°C;

f, after being incubated 12min at 750 DEG C, add zinc ingot;

g. After 20min of heat preservation, the melt is stirred at a constant speed for 8min, then slag is removed, and it is left to stand for 15min;

h. The melt is poured into the mold, and the mold is demolded to obtain an ordinary solidified state Mg-6.0wt% Zn-1.2wt% Y-2.0wt%Nd-0.3wt%Sc alloy (intermediate product).

3. Preparation of extruded alloy samples

a. The prepared ordinary solidified state Mg-6.0wt% Zn-1.2wt% Y-2.0wt% Nd-0.3wt%Sc alloy (intermediate product) is subjected to solution treatment, and the solution temperature is 500 ° C. The time is 4h;

b, carry out an extrusion after the solid solution, the extrusion temperature is 480°C, the extrusion ratio is 10, the extrusion rate is 3m/min, and the heating temperature of the die in the extrusion process is 470°C, and an extrusion can be obtained. state product;

c, carry out solution treatment to the one-time extruded product, the solution temperature is 500 ° C, and the solution time is 6h; after the solid solution, the secondary extrusion is carried out, the extrusion temperature is 420 ° C, and the extrusion ratio is 12, and the extrusion ratio is 12. The speed was 3m/min, and the heating temperature of the die during extrusion was 400°C to obtain the final product.

Example 6

The magnesium alloy for absorbable orthopaedic implants is composed of: 2.0wt% Zn, 0.8wt% Y, 0.6wt% Nd, 0.2wt% Sc, the balance is Mg, and unavoidable impurity elements.

1. Preliminary preparation

The raw materials required for this example are:

High-purity magnesium ingot (purity ≥99.9%): 2671g

High-purity zinc ingot (purity ≥99.9%): 72g, in which the content of Zn is 1.2 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Y master alloy: 106g, wherein the content of Y is 1.1 times that in the obtained magnesium alloy (target product);

Mg-25.0wt% Nd master alloy: 79g, wherein the content of Nd is 1.1 times that in the obtained magnesium alloy (target product);

Mg-10.0wt% Sc master alloy: 72g, wherein the content of Sc is 1.2 times that in the obtained magnesium alloy (target product);

In order to avoid the oxidation and combustion of the magnesium alloy, there is always a protective gas in the furnace during the whole smelting process. The protective gas used in this embodiment is a mixture of carbon dioxide and sulfur hexafluoride, and the volume ratio of carbon dioxide and sulfur hexafluoride is 100. :1.

2. Preparation of intermediate products

a. Heat the crucible, the slag removal tool, the stirring rod and the mold to 120°C, then take it out, apply a thin and uniform coating on the surface, and put it into an oven for drying;

B, put the processed crucible into the resistance furnace, set the furnace temperature to 400 ° C, when the furnace temperature rises to the set temperature, feed carbon dioxide and sulfur hexafluoride gas mixture;

c, after 10min of mixed gas, add high-purity magnesium ingot, and furnace temperature is raised to 700 ℃ simultaneously;

d, at 700 DEG C, be incubated until after the magnesium ingot is completely melted, add the Mg-Sc master alloy, and the furnace temperature is raised to 800 DEG C, and is incubated for 60min;

e. After the heat preservation, add Mg-Y master alloy and Mg-Nd master alloy, and reduce the furnace temperature to 700°C;

f, after insulation 10min at 700 DEG C, add zinc ingot;

g. After 20min of heat preservation, the melt is stirred at a constant speed for 5min, then slag is removed, and it is left to stand for 15min;

h. The melt is poured into the mold, and the mold is demolded to obtain an ordinary solidified Mg-4.0wt% Zn-0.8wt%Y-0.6wt%Nd-0.2wt%Sc alloy (intermediate product).

3. Preparation of extruded alloy samples

a. The prepared ordinary solidified state Mg-4.0wt% Zn-0.8wt%Y-0.6wt%Nd-0.2wt%Sc alloy (intermediate product) is subjected to solution treatment, and the solution temperature is 460 ° C. The time is 1h;

b, carry out an extrusion after the solid solution, the extrusion temperature is 450°C, the extrusion ratio is 7, the extrusion rate is 4m/min, and the heating temperature of the die in the extrusion process is 430°C, and an extrusion can be obtained. state product;

c, carry out solution treatment to the one-time extruded product, the solution temperature is 460 ° C, and the solution time is 2h; after the solid solution, carry out secondary extrusion, the extrusion temperature is 380 ° C, and the extrusion ratio is 12, and the extrusion ratio is 12. The speed was 2m/min, and the heating temperature of the die during extrusion was 360°C to obtain the final product.

Performance Testing

After testing, the room temperature yield strength of the magnesium alloy in the secondary extrusion state prepared in Example 1 is 300±5MPa, the tensile strength is 320±3MPa, and the elongation can reach 20%; The room temperature yield strength of the magnesium alloy is 310±5MPa, the tensile strength is 330±5MPa, and the elongation can reach 18%, all of which meet the requirements of magnesium alloys for orthopaedic implants.

The microstructure, mechanical properties and electrochemical properties of the as-cast and double-extruded magnesium alloys prepared in Example 4 were tested.

The tensile properties test results are shown in Figure 1. The yield strength of the as-cast magnesium alloy at room temperature is 120±10MPa, the tensile strength is 165±10MPa, and the elongation is 9%; while the magnesium alloy in the secondary extrusion state is at The yield strength at room temperature is 306±5MPa, the tensile strength is 325±6MPa, and the elongation can reach 19%. After two extrusion processes, the strength and shape of the magnesium alloy have been greatly improved.

The microstructure of the as-cast magnesium alloy is shown in Figure 2(a). It can be seen that the magnesium alloy is composed of coarse equiaxed grains with a size of about 100 μm, and the second phase is continuously distributed at the grain boundaries. The microstructure of the secondary extruded magnesium alloy is shown in Figure 2(b). It can be seen that the magnesium alloy is composed of fine and uniform equiaxed grains and relatively coarse elongated grains. The mixed grain structure, in which the equiaxed grains The grain size of the crystal reaches 1~2 μm, and the elongated grains are about 100 μm long and 5 μm wide, and are linearly distributed along the extrusion direction. It can be seen from the EDS composition analysis diagram of Fig. 2(c) that the second phase in both as-cast and as-extruded alloys is W-phase (Mg ₃ Zn ₃ Y ₂ ). At the same time, there are also fine nano-sized precipitates in the alloy in the secondary extrusion state, which are uniformly dispersed in the alloy matrix. The refinement of grains and second phases will greatly improve the mechanical properties of magnesium alloys.

The room temperature tensile fractures of the as-cast and double-extruded magnesium alloys are shown in Figure 3. It can be seen that the fractures of the as-cast alloys show a mixed fracture mode of ductility and brittleness, as shown in Figures 3(a) and (b), The fracture of the secondary extrusion alloy is mainly composed of a large number of dimples, as shown in Fig. 3(c) and (d), and the tensile fracture mode is ductile fracture. Therefore, after the two-pass extrusion process, the toughness of the magnesium alloy obtained in Example 4 is improved.

The electrochemical corrosion test results of as-cast and double-extruded magnesium alloys are shown in Figure 4. From the figure, it can be obtained that the self-corrosion potential of as-cast magnesium alloys is -1.4097, and the corrosion current density is 1.3122×10 ^-5 A/cm ² ; the self-corrosion potential of the magnesium alloy in the secondary extrusion state is -1.336V, and the corrosion current density is 5.43×10 ^-5 A/cm ² . The corrosion resistance has also been improved, and its corrosion resistance can meet the requirements of magnesium alloys for absorbable orthopaedic implants.

The as-cast and twice-extruded magnesium alloys were prepared with leaching solutions with concentrations of 10%, 50% and 100%, respectively, and the human umbilical vein endothelial cells were cultured with the leaching solution for 48 hours. The measured relative cell activity results are shown in the figure. As shown in Figure 5, it can be seen from the figure that the cell activity of the magnesium alloy leaching solution in the as-cast state and the secondary extruded state is higher after culture; the observed cell morphology results are shown in Figure 6, in which the as-cast magnesium alloy Figures 6(a), (b), and (c) show the cell morphology of the leaching solutions with alloy concentrations of 10%, 50%, and 100%, while the secondary extruded magnesium alloy concentrations were 10%, 50%, and 50%. % and 100% leaching solution cultured cell morphology is shown in Figure 6(d), (e) and (f). From Figure 6 it can be seen that all cells are in good shape. Combined with the results in Fig. 5 and Fig. 6, it is proved that both the as-cast and the double-extruded magnesium alloy obtained in Example 4 have good biocompatibility.

The room temperature yield strength of the magnesium alloy in the secondary extrusion state prepared in Example 6 is 270±5MPa, the tensile strength is 300±5MPa, and the elongation is 15.5%. Figure 7 shows the test results of room temperature tensile properties of the secondary extruded magnesium alloy obtained in Example 4 and Example 6. The Zn content of Example 6 is 2% higher than that of Example 4, which is lower than The Sc content was unchanged. It can be found that with the increase of Zn content, the room temperature yield strength, tensile strength and elongation of magnesium alloys have been improved, indicating that the increase of Zn content can effectively improve the room temperature tensile properties of magnesium alloys.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, All should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (1)

1. An absorbable orthopaedic implant magnesium alloy, characterized in that it is composed of the following components by mass percentage: 4.0wt% of Zn, 0.8wt% of Y, 0.6wt% of Nd, 0.2wt% of Sc, and the remainder The amount is Mg, and inevitable impurity elements; The magnesium alloy is prepared according to the following steps: 1. Preliminary preparation The raw materials required are: High-purity magnesium ingot (purity ≥99.9%): 2599g High-purity zinc ingot (purity ≥99.9%): 144g, wherein the content of Zn is 1.2 times that in the obtained magnesium alloy (target product); Mg-25.0wt% Y master alloy: 106g, wherein the content of Y is 1.1 times that in the obtained magnesium alloy (target product); Mg-25.0wt% Nd master alloy: 79g, wherein the content of Nd is 1.1 times that in the obtained magnesium alloy (target product); Mg-10.0wt% Sc master alloy: 72g, wherein the content of Sc is 1.2 times that in the obtained magnesium alloy (target product); In order to avoid the oxidation and combustion of magnesium alloys, there is a protective gas in the furnace throughout the smelting process. The protective gas used is a mixture of carbon dioxide and sulfur hexafluoride, and the volume ratio of carbon dioxide and sulfur hexafluoride is 100:1; 2. Preparation of intermediate products a. Heat the crucible, slag removal tool, stirring rod and mold to 120°C, then take it out, apply a thin and uniform coating on the surface, and put it in an oven for drying; b. Put the treated crucible into the resistance furnace, set the furnace temperature to 400 °C, and when the furnace temperature rises to the set temperature, introduce a mixture of carbon dioxide and sulfur hexafluoride; c. After passing the mixed gas for 10 minutes, add high-purity magnesium ingots, and at the same time raise the furnace temperature to 700 °C; d. Keep the temperature at 700°C until the magnesium ingot is completely melted, add the Mg-Sc master alloy, and raise the furnace temperature to 800°C for 60 minutes; e. After the heat preservation, add Mg-Y master alloy and Mg-Nd master alloy, and reduce the furnace temperature to 700 ℃; f. After keeping the temperature at 700°C for 10min, add zinc ingots; g. After 20min of heat preservation, the melt is stirred at a constant speed for 5min, then slag is removed, and it is left to stand for 15min; h. The melt is poured into a mold and demolded to obtain an ordinary solidified Mg-4.0wt%Zn-0.8wt%Y-0.6wt%Nd-0.2wt%Sc alloy (intermediate product); 3. Preparation of extruded alloy samples a. The prepared ordinary solidified Mg-4.0wt%Zn-0.8wt%Y-0.6wt%Nd-0.2wt%Sc alloy (intermediate product) is subjected to solution treatment, the solution temperature is 460 ℃, and the solution time is is 1h; b. After solid solution, carry out one extrusion, the extrusion temperature is 450℃, the extrusion ratio is 7, the extrusion rate is 4m/min, and the heating temperature of the die during the extrusion process is 430℃, and the extruded product can be obtained once ; c. Perform solution treatment on the first extruded product, the solution temperature is 460°C, and the solution time is 2h; after solid solution, the second extrusion is performed, the extrusion temperature is 380°C, the extrusion ratio is 12, and the extrusion rate is 2m/min, the heating temperature of the die during extrusion was 360°C, and the final product was obtained.

Images