CN115874088A - A kind of high-strength heat-resistant and damage-resistant aluminum alloy powder, preparation method and application - Google Patents

Abstract

The invention discloses a high-strength, heat-resistant and damage-resistant aluminum alloy powder, a preparation method and an application thereof. The composition of the aluminum alloy powder includes the following components calculated according to mass percentage: Mg: 4.0-12%, Ca: 0.50-3.0%, Sc : 0.10-0.90%, Mn: 0.20-1.5%, Zr: 0.1-0.5%, and the rest are Al and inevitably introduced impurity elements. The addition of the alloying element Ca significantly suppresses the thermal cracking tendency of the alloy during the 3D printing forming process. The high-strength heat-resistant Al-Mg-Ca-Sc alloy powder involved in the present invention has good 3D printing formability. After 3D printing, Parts do not produce cracks, high density. By building a multi-scale structure and exerting a multi-level strengthening mechanism, the 3D printed sample has excellent room temperature mechanical properties and high temperature stability.

Description

A kind of high-strength heat-resistant and damage-resistant aluminum alloy powder, preparation method and application

technical field

The invention belongs to the technical field of additive manufacturing materials, and in particular relates to a high-strength heat-resistant and damage-resistant aluminum alloy powder, a preparation method and an application thereof.

Background technique

Additive manufacturing technology has been widely used in aerospace, rail transit, biomedical and other fields due to its advantages of easy forming of complex structures, short manufacturing cycle, energy saving and material reduction. Among them, powder bed-based selective laser melting (Selective Laser Melting, SLM) forming is one of the first representative additive manufacturing technologies developed. Aluminum alloy is one of the most widely used structural materials, and its laser additive manufacturing is becoming more and more important in the field of lightweight, high-performance aluminum-based complex parts manufacturing.

At present, laser additive manufacturing of aluminum alloys is mainly based on traditional casting grade alloys, and there are the following problems:

(1) Al-Si-based near-eutectic alloys represented by AlSi10Mg and AlSi12 have relatively coarse eutectic structures and limited strength and elongation; the mechanical properties of AlSi10Mg alloys produced by SLM are usually within the tensile strength range of 214 to 358MPa , the elongation after heat treatment is 4 to 15%. (2) Conventional medium-high-strength aluminum alloys such as 2xxx series aluminum alloys and 7xxx series aluminum alloys are prone to thermal cracking during the additive manufacturing process, which is a key bottleneck restricting their further development; (3) Another option is to combine with Sc and /or Zr alloyed 5xxx series aluminum alloys, the representative Al-Mg-Sc-Zr alloy called Scalmalloy, due to the strengthening of fine Al3(Sc,Zr) particles and the solid solution strengthening of Mg, the performance Good room temperature strength and plasticity. However, for Scalmalloy and alloys with similar compositions, avoiding hot cracking tendency and improving mechanical properties largely depend on high levels of rare element Sc (>0.66 wt%). In addition, poor thermal stability and sharp drop in mechanical properties at high temperature limit their applications. (4) In order to expand the application of additively manufactured aluminum alloys at high temperatures, new heat-resistant aluminum alloys are designed for additive manufacturing, such as Al-Ce-based and Al-Ni-based aluminum alloys. However, the above alloys have low room temperature strength and poor ductility.

In the prior art, the materials for additive manufacturing are also improved. For example, the patent CN111922331A provides a nanoparticle-reinforced aluminum alloy powder and a preparation method thereof, including the following steps: (1) dissolving nanopowder A and nanopowder B in an organic solvent Disperse evenly, obtain mixing system C, described nano-powder A is at least one of nano-Ti powder, nano-Ta powder, nano-Nb powder and nano-Zr powder, and described nano-powder B is nano-boron powder; (2) bonding (3) Add the mixed system D to the aluminum alloy powder under stirring until the aluminum alloy powder forms agglomerated particles and continue to stir until the organic solvent volatilizes to obtain solid particles E; (4) Screening solid particles E to remove particles with a particle size greater than 270 meshes, the aluminum alloy powder prepared by this patent has good mechanical properties for application, and the aluminum alloy material prepared by selective laser melting has no crack defects, but is heat-resistant Poor resistance, low strength at room temperature.

Patent CN110791686A discloses an aluminum alloy powder material and a preparation method for additive manufacturing. The expression of the aluminum alloy powder material is: Al-X-Y, X component is one or more of Fe, Co, Ni, Y component is one or more of Sc, Ti, Zr, wherein, X group The atomic percentage of the Y component is 0.1-10%, the atomic percentage of the Y component is 0.1-5%, and the rest of the components are Al. The preparation method is as follows: batching according to the expression of aluminum alloy powder, adopting heating method to melt and prepare master alloy ingot, and then atomizing the master alloy ingot to make powder, so as to obtain aluminum alloy powder material. Compared with the previous patent, the aluminum alloy powder additive manufacturing formed parts produced by this patent have better mechanical properties, better thermal stability, and improved high-temperature strength, but poor ductility and low density. Difference.

Therefore, it is still urgent to develop an aluminum alloy with high strength and toughness at room temperature and good thermal stability at high temperature, which can effectively inhibit thermal crack damage during 3D printing and has good density.

Contents of the invention

In order to achieve the above object, one aspect of the present invention proposes a high-strength, heat-resistant and damage-resistant aluminum alloy powder. The composition of the aluminum alloy powder is calculated according to mass percentage: Mg: 4.0-12%, Ca: 0.50-3.0%, Sc: 0.10-0.90%, Mn: 0.20-1.5%, Zr: 0.1-0.5%, and the rest are Al and unavoidable impurity elements.

Another aspect of the present invention provides a method for preparing a high-strength heat-resistant and damage-resistant aluminum alloy powder, comprising the following steps:

Step 1, preparing elemental components: the compositional components of the aluminum alloy powder include Mg, Ca, Sc, Mn, Zr, and the remaining components are Al;

Step 2. Vacuum smelting-atomization pulverization: the high-strength heat-resistant aluminum alloy powder prepared in step 1 is vacuum smelted; after the vacuum smelting, atomization pulverization is carried out to obtain the high-strength heat-resistant and damage-resistant aluminum alloy powder alloy powder.

Preferably, in the step 2, the smelting temperature of the vacuum smelting is 750-850° C., and the vacuum degree is ≤0.1 Pa.

Preferably, in the step 2, the vacuum atomization process is to pass through Ar, He or a mixed gas protection and gas atomization, and the atomization pressure is 0.3-10 MPa.

Another aspect of the present invention provides an application of a high-strength heat-resistant and damage-resistant aluminum alloy powder material in the selective laser melting forming 3D printing technology.

Preferably, applying the prepared aluminum alloy powder in 3D printing includes the following steps:

Step 1. heat-preserve the aluminum alloy powder in an inert gas at a temperature of 300-400° C. for 3-6 hours;

Step 2, 3D printing the pretreated powder.

Preferably, the aluminum alloy powder is subjected to selective laser melting molding treatment, wherein the laser power is 200-400W, the scanning speed is 500-2000mm/s, the scanning distance is 50-120μm, and the interlayer thickness is 20-50μm.

Preferably, after step 2, the 3D printed alloy is subjected to heat treatment, the heat treatment temperature is 300-420° C., and the time is 3-36 hours.

Compared with prior art, the beneficial effect of the present invention:

(1) The high-strength heat-resistant Al-Mg-Ca-Sc alloy powder disclosed in the present invention significantly suppresses the thermal cracking tendency of the alloy during the 3D printing forming process through the addition of the alloying element Ca. Al-Mg-Ca-Sc alloy powder has good 3D printing formability. After 3D printing, the parts do not produce cracks and have high density. By building a multi-scale structure and exerting a multi-level strengthening mechanism, the 3D printed sample has excellent room temperature mechanical properties and high temperature stability.

(2) Another beneficial effect of the present invention is that the specific combination of aluminum alloy powder exerts the synergistic effect of multiple strengthening such as solid solution strengthening, grain boundary strengthening and nano-precipitated phase strengthening, and has high room temperature strength and plasticity. Among them, the gold element Mg is solid-dissolved in the aluminum alloy matrix, which plays a role of solid solution strengthening; the alloy element Ca forms a network/semi-network eutectic structure at the grain boundary, and exerts the effects of grain boundary strengthening and second phase strengthening; Sc Al3(Sc, Zr) nanophase is formed with Zr, on the one hand, it acts as a heterogeneous nucleation point in the solidification process, and refines the grains; The precipitated phase exerts the dispersion strengthening effect.

(3) The specific combination of aluminum alloy powder disclosed in the present invention has excellent thermal stability, and the loss of mechanical properties is small under high temperature conditions. This is mainly due to: on the one hand, the network/semi-network eutectic structure formed by the alloying element Ca on the grain boundary has an obvious pinning effect on the grain boundary and inhibits the growth of the grain; on the other hand, the intragranular The coherent/semi-coherent Al3(Sc,Zr) nanophase has good thermal stability, and the dispersion strengthening effect is not significantly weakened.

The above description is only an overview of the technical solution of the present application. In order to understand the technical means of the present application more clearly, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present application more obvious and understandable , the preferred embodiments of the application and accompanying drawings are described in detail below.

According to the following detailed description of specific embodiments of the application in conjunction with the accompanying drawings, those skilled in the art will be more aware of the above and other objectives, advantages and features of the application.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are For some embodiments of the present application, those of ordinary skill in the art can also obtain other drawings based on these drawings without creative effort. Throughout the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, elements or parts are not necessarily drawn in actual scale.

Fig. 1 is the morphology figure of high-strength, heat-resistant and damage-resistant aluminum alloy powder of the present invention;

Fig. 2 is a particle size distribution diagram of the high-strength, heat-resistant and damage-resistant aluminum alloy powder of the present invention;

Fig. 3 is the optical mirror image of the aluminum alloy powder under the selected area laser melting molding process of the present invention, and Fig. 3a-3c is the optical mirror image of the aluminum alloy powder under the selected area laser melting forming process with different processing parameters picture;

Fig. 4 is the transmission electron microscope HADDF diagram of the high-strength heat-resistant and damage-resistant aluminum alloy powder of the present invention after 3D printing and the distribution of corresponding Ca elements;

Fig. 5 is a high-resolution transmission electron microscope image of the high-strength heat-resistant and damage-resistant aluminum alloy powder of the present invention after 3D printing, showing nano-dispersed second phase particles;

Fig. 6 is a diagram of the mechanical properties of the 3D printed aluminum alloy according to the present invention under different temperature conditions;

Fig. 7 is a comparison diagram of the mechanical properties of the 3D printed aluminum alloy of the present invention and other alloys under different temperature conditions;

Fig. 8 is a graph showing the variation of the thermal crack sensitivity factor of the 3D printed aluminum alloy according to the present invention with the Ca content.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of this application, not all of them. In the following description, specific details, such as specific configurations and components, are provided merely to help a comprehensive understanding of the embodiments of the present application. Accordingly, those of ordinary skill in the art should recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the application. Also, descriptions of well-known functions and constructions are omitted in the embodiments for clarity and conciseness.

The term "and/or" in this article is just an association relationship describing associated objects, which means that there may be three relationships, for example, A and/or B, which can mean: A exists alone, B exists alone, and A and B exist simultaneously. In the three cases of B, the term "/and" in this article is to describe another associated object relationship, which means that there can be two relationships, for example, A/ and B, which can mean: there is A alone, and there are two cases of A and B alone , In addition, the character "/" in this article generally indicates that the contextual objects are an "or" relationship.

It should also be noted that in this article, relational terms such as first and second etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations Any such actual relationship or order exists between. Moreover, the terms "comprises", "comprises" or any other variation thereof are intended to cover a non-exclusive inclusion.

Example 1

In this embodiment, a high-strength heat-resistant and damage-resistant aluminum alloy powder is prepared.

Step 1. Prepare elemental components: the components of the aluminum alloy powder include, by mass percentage, Mg: 5%, Ca: 1%, Sc: 0.6%; Zr: 0.3%; Mn: 0.6%, which are inevitably introduced The impurity element is less than 0.25%, and the rest is Al.

Step 2. Vacuum smelting-atomization pulverization: the preparation method of the above alloy powder is to mix according to the mass ratio, and then conduct atomization pulverization after the vacuum smelting to obtain the high-strength heat-resistant and damage-resistant aluminum alloy powder.

The vacuum melting temperature in step 2 is 820° C., and the vacuum degree is 0.01 Pa. Then, argon gas is used as the medium to atomize the metal droplet, and the atomization pressure is 5 MPa. The aluminum alloy powder was subjected to heat preservation treatment at 350° C. for 4 hours in an argon atmosphere.

The prepared aluminum alloy powder is shown in Fig. 1 and Fig. 2. Fig. 1 is a topography diagram of the high-strength heat-resistant and damage-resistant aluminum alloy powder according to the method of the present invention, and Fig. 2 is a profile of the high-strength heat-resistant and damage-resistant aluminum alloy powder according to the present invention. Particle size distribution diagram. The particles whose particle size is less than 55.4 μm account for 90%, and the particles whose particle size is less than 25.4 μm account for 50%. By adding the alloying element Ca to the aluminum alloy powder to be prepared, the thermal cracking tendency of the alloy during the 3D printing forming process is significantly suppressed. Among them, the gold element Mg is solid-dissolved in the aluminum alloy matrix, which plays a role of solid solution strengthening; the alloy element Ca forms a network/semi-network eutectic structure at the grain boundary, and exerts the effects of grain boundary strengthening and second phase strengthening; Sc Al3(Sc, Zr) nanophase is formed with Zr, on the one hand, it acts as a heterogeneous nucleation point in the solidification process, and refines the grains; The precipitated phase exerts the dispersion strengthening effect.

Further, the prepared aluminum alloy powder material is applied in the selective laser melting forming 3D printing technology. As shown in Fig. 3a, Fig. 3a is an optical microscope image of the aluminum alloy powder processed by the selective laser melting molding process. The above-prepared aluminum alloy powder was subjected to selective laser melting (SLM) process, and the process parameters in this embodiment were: laser power 350W, scanning speed 800mm/s, scanning distance 80μm, interlayer thickness 30μm. A sample with good forming quality and high density was prepared through the above-mentioned 3D printing process, and no obvious defects such as holes and cracks were observed inside the sample.

Example 2

The difference between this example and Example 1 is that the alloy in Example 1 is in a printed state without heat treatment, while the aluminum alloy in this example is obtained from the alloy in Example 1 after heat treatment at 325° C. for 9 hours. As shown in Figure 5, Figure 5 is a high-resolution transmission electron microscope image of the high-strength heat-resistant and damage-resistant aluminum alloy powder of the present invention after 3D printing, showing nano-dispersed second-phase particles. Through the above heat treatment, dispersed Al3(Sc, Zr) nano phases are precipitated inside the sample, which exerts the effect of dispersion strengthening and significantly improves the strength of the alloy.

Example 3

The difference between this embodiment and embodiment 1 is that, as shown in Fig. 3b, Fig. 3b is an optical microscope image of the aluminum alloy powder processed by the selective laser melting molding process. The prepared aluminum alloy powder was subjected to a selective laser melting molding (SLM) process. In this embodiment, the process parameters were: laser power 350W, scanning speed 700 mm/s, scanning distance 80 μm, interlayer thickness 30 μm . After the above treatment, at low scanning speed, the energy density is high, which will lead to the gasification of the metal liquid formed after the powder is melted, forming metal vapor, and forming pores in the sample.

Example 4

The difference between this embodiment and Embodiments 1 and 3 is that, as shown in FIG. 3c, FIG. 3c is an optical microscope image of the aluminum alloy powder subjected to selective laser melting molding process. The prepared aluminum alloy powder was subjected to a selective laser melting (SLM) process. In this embodiment, the process parameters were 300 W laser power, 1000 mm/s scanning speed, 80 μm scanning distance, and 30 μm interlayer thickness. The sample prepared by the above 3D printing process has good quality and high density, and no obvious holes, cracks and other defects are observed inside the sample.

Example 5

Based on the above examples, the prepared high-strength, heat-resistant and damage-resistant aluminum alloy powder material was 3D printed, and the 3D printed sample was milled, cleaned, and cut into room temperature/high temperature tensile sample size by wire cutting; Further, the tensile specimens were ground and cleaned with alcohol.

Among them, the room temperature and high temperature tensile samples were completed on CMT5205 and CMT5808 testing machines respectively. As shown in Fig. 6, Fig. 6 is a diagram of the mechanical properties of the 3D printed aluminum alloy according to the present invention under different temperature conditions. Select the treated sample in embodiment 1 and the processed sample in embodiment 2 respectively, and observe the changes of the stress-strain curves at different temperatures. Including: the change of the stress-strain curve of the sample of Example 1 at a temperature of 25°C, and the change of the stress-strain curve of the sample of Example 2 at a temperature of 25°C, 150°C, and 250°C. Wherein, the mechanical performance test data of the samples in Example 2 under different temperature conditions are shown in Table 1 below.

The mechanical property result of table 1 embodiment 2 under different temperature conditions

Embodiment 2 Compared with the reported 3D printing aluminum alloy (Scalmalloy alloy, AlSi10Mg) and cast alloy, the sample has excellent comprehensive mechanical properties, as shown in Figure 7, Figure 7 is the 3D printing aluminum alloy of the present invention Comparison of mechanical properties with other alloys at different temperatures. Including high strength and ductility at room temperature, and excellent thermal stability at high temperature with little loss of strength.

The excellent mechanical properties of a high-strength heat-resistant and damage-resistant aluminum alloy are derived from the synergistic effect of solid solution strengthening, ordered strengthening of nanoparticles and grain boundary strengthening. As shown in Figure 4, Figure 4 is the HADDF diagram of the transmission electron microscope and the distribution of the corresponding Ca element after the high-strength, heat-resistant and damage-resistant aluminum alloy powder of the present invention has been 3D printed. The semi-network Al4Ca along the grain boundary suppresses the grain growth at high temperature and maintains high strength.

Compared with cast alloys, the increase in strength is mainly due to the rapid solidification during the additive manufacturing process, which leads to the reduction in the size of grains and Al ₃ (Sc, Zr) nanoparticles, as shown in Figure 5, which is a high-strength alloy according to the present invention. The high-resolution transmission electron microscope image of heat-resistant and damage-resistant aluminum alloy powder after 3D printing shows nano-dispersed second phase particles.

The addition of alloying element Ca in the aluminum alloy powder for 3D printing proposed in this application significantly suppresses the hot cracking tendency of the alloy. As shown in FIG. 8 , FIG. 8 is a graph showing the variation of the thermal crack sensitivity factor of the 3D printed aluminum alloy according to the present invention with the Ca content. The addition of Ca significantly reduces the crack sensitivity of the alloy. At the same time, no obvious hot cracking phenomenon was found in the 3D printed samples in a wide printing process window, which proves that the high-strength, heat-resistant and resistant alloy disclosed in this application Damage Aluminum alloy powder has the obvious advantage of inhibiting damage during the preparation process of 3D printing.

The above descriptions are only preferred embodiments of the present application, which are not intended to limit the scope of protection of the present application. For those skilled in the art, various modifications and changes can be made to the present application. Within the spirit and principles of the application, changes, modifications, replacements, integrations and parameter changes of these embodiments can be achieved through conventional substitutions or can achieve the same function without departing from the principles and spirit of the application. Into the scope of protection of this application.

Claims (8)

1. The high-strength heat-resistant damage-resistant aluminum alloy powder is characterized by comprising the following components in percentage by mass: mg:4.0 to 12%, ca: 0.50-3.0%, sc:0.10 to 0.90%, mn:0.20 to 1.5%, zr:0.1 to 0.5 percent, and the balance of Al and inevitable introduced impurity elements.

2. A method of making a high strength, heat resistant, damage tolerant aluminum alloy powder as recited in claim 1 comprising the steps of:

step 1, preparing element components: the aluminum alloy powder comprises the following components of Mg, ca, sc, mn and Zr, and the balance of Al;

step 2, vacuum melting-atomization powder preparation: vacuum smelting is carried out on the high-strength heat-resistant aluminum alloy powder prepared in the step 1; and atomizing to prepare powder after vacuum melting, thus obtaining the high-strength heat-resistant damage-resistant aluminum alloy powder.

3. The method for preparing high-strength heat-resistant damage-resistant aluminum alloy powder according to claim 2, wherein in the step 2, the melting temperature of vacuum melting is 750-850 ℃, and the vacuum degree is less than or equal to 0.1Pa.

4. The method for preparing high-strength heat-resistant damage-resistant aluminum alloy powder according to any one of claims 2 or 3, wherein in the step 2, the vacuum atomization process is performed by introducing Ar, he or mixed gas for protection and atomizing, and the atomization pressure is 0.3-10 MPa.

5. Use of the high strength, heat and damage resistant aluminium alloy powder according to claim 1 in 3D printing technology.

6. The application of the high-strength heat-resistant damage-resistant aluminum alloy powder in 3D printing according to claim 5, wherein the prepared aluminum alloy powder is applied in 3D printing, and the method comprises the following steps:

firstly, heat-preserving the aluminum alloy powder in inert gas at the temperature of 300-400 ℃ for 3-6 h;

and step two, performing 3D printing on the powder subjected to heat preservation treatment.

7. The use of a high strength heat and damage resistant aluminum alloy powder in 3D printing as claimed in claim 6, wherein the aluminum alloy powder is subjected to selective laser melting forming treatment, wherein the laser power is 200-400W, the scanning speed is 500-2000 mm/s, the scanning pitch is 50-120 μm, and the interlayer thickness is 20-50 μm.

8. Use of a high strength heat resistant damage tolerant aluminium alloy powder in 3D printing according to any one of claims 6 or 7 wherein after step two the 3D printed alloy is heat treated at a temperature of 300 to 420 ℃ for a period of 3 to 36 hours.

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