CN109182810A

CN109182810A - A kind of low cost high-temperature-room type plasticity wrought magnesium alloy and preparation method thereof

Info

Publication number: CN109182810A
Application number: CN201811375906.6A
Authority: CN
Inventors: 孟帅举; 韩海生; 李其智; 张士良; 余晖; 闻晶晶; 范少达; 李永胜; 赵维民
Original assignee: Hebei University of Technology
Current assignee: Beijing Zhong'an Jingrun New Material Technology Co ltd
Priority date: 2018-11-19
Filing date: 2018-11-19
Publication date: 2019-01-11
Anticipated expiration: 2038-11-19
Also published as: CN109182810B

Abstract

The invention relates to a low-cost and high-temperature plastic deformation magnesium alloy and a preparation method thereof. The alloy is a Mg-Bi-Sn-Zr-Ca-Y alloy, and its chemical composition mass percentage is: Bi 2-5.0wt%; Sn 2-5.0wt%; Zr 0.5-1.2wt%; Ca 0.1-0.8wt% ; Y 0.01-0.08wt%, the rest is Mg and inevitable impurities; and the mass ratio Bi:Ca=6-7:1. The invention uses extremely simple processing means to obtain deformed magnesium alloy with high room temperature plasticity, the room temperature elongation reaches more than 35%, and meanwhile, the raw material and processing cost are low, and mass production is easy to be realized.

Description

A kind of low cost high-temperature-room type plasticity wrought magnesium alloy and preparation method thereof

Technical field

The present invention relates to metal material and metal material processing field, in particular to a kind of inexpensive high-temperature-room type plasticity deformation Magnesium alloy and preparation method thereof；The novel magnesium alloy can be used as potential heat resistance magnesium alloy and biological medical magnesium alloy material.

Background technique

The energy, material and information are three big pillars of human social development, increasingly serious with energy-saving and emission-reduction situation, are opened Hair and be inexorable trend using resourceful lightweight mg-based material.Magnesium density is about 1.74g/cm³, about the 2/3 of aluminium alloy, The 1/4 of steel, magnesium alloy have density small, and specific strength, specific stiffness are higher, and effectiveness is good, and damping shock absorption waits well one Number of advantages is known as " 21st century green metal engineering material ", leads in aerospace, telecommunications and communications and transportation etc. Domain has broad application prospects.At present, in terms of the demand of global magnesium alloy and research and development situation, Magnesium Alloy Development research work master It will be towards high-strength magnesium alloy, high plastic magnesium alloy, heat resistance magnesium alloy, the directions such as fiber or particle reinforced magnesium base compound material hair Exhibition.

However, in terms of high plastic magnesium alloy exploitation, since the crystal structure of magnesium and its most alloys is solid matter six Square, bootable slip system causes its temperature-room type plasticity bad less under the conditions of low temperature (220 DEG C of <).Only cylinder at relatively high temperatures Sliding and conical surface slip system can start, and improve the plasticity of magnesium alloy.But in magnesium alloy process, temperature too it is high often Lead to magnesium alloy grain coarsening, deteriorates the mechanical property of alloy, while the processes such as heating and thermal insulation also improve alloy processing cost. Therefore exploitation under room temperature or lower temperature with superior plasticity magnesium alloy be advantageously implemented magnesium alloy at low temperature even room The lower plastic processing of temperature, and then alloy structure is avoided to deteriorate, enhances product performance, at the same reduce during it is further processed by The costs such as the energy consumption that blank heating introduces, are greatly facilitated magnesium alloy as novel green material in automobile, rail traffic, aviation etc. The extensive use in field.

In recent years, with being increasingly urgent to transport facility lightweight requirements, have a lot of research work and pass through respectively Kind of method prepares high-temperature-room type plasticity magnesium alloy, gradually has some high-temperature-room type plasticity magnesium alloys to developed successively both at home and abroad. Patent 1 (application publication number: CN1616697C) discloses a kind of high plastic magnesium alloy containing rare-earth yttrium, by Mg, Zn, Zr, Y group At each component mass percent is Zn:5.0-8.5%；Zr:0.6-0.8%；Y 0.7-2.0%, remainder is for magnesium and not It can avoid impurity.After extrusion process, which can achieve 18.37-21.45%, and whole plasticity is still relatively low. Patent 2 (application publication number: CN102925771A) discloses a kind of High-room-temperaturductility ductility magnesium alloy material and preparation method thereof: by matter Measure percentage Li:1.0-5.0%, Al:2.5-3.5%, Zn:0.7-1.3%, Mn:0.2-0.5%, impurity≤0.3%, more than magnesium Amount.It is made by melting under conditions of vacuumizing again by the pure lithium of formula and AZ31 magnesium alloy and be passed through inert gas, gained closes Golden elongation percentage at room temperature is between 14-31%.Alloy smelting process is complicated, and whole room temperature elongation percentage is still relatively low.Patent 3 (application publication number: CN102061414A) discloses a kind of high plastic magnesium alloy and preparation method thereof, ingredient are as follows: Al:0.5- 2%, Mn:2%, Ca:0.02-0.1%, surplus are magnesium, and room temperature elongation percentage can achieve 25%.Send elsewhere bright cost of alloy compared with It is low, but elongation percentage is still whole relatively low.

These existing related inventions or preparation process are more demanding to working condition, or contain more rare earth element Equal precious metal elements, these all directly or indirectly increase cost of alloy, and the temperature-room type plasticity that alloy has mostly is still inclined It is low.

For preferably meet consumer electronics, automobile and other industries to high-strength magnesium alloy low cost, easy processing, high performance want It asks, there is an urgent need to develop go out that rare earth can be free of with the preparation of simple process of manufacture or contain the low cost of trace rare-earth The magnesium alloy materials of high-temperature-room type plasticity, it is alloy properties to improve directly to use or carry out further cold plasticity processing as blank Can, to promote the further genralrlization application of magnesium alloy.

Summary of the invention

It is not high enough for temperature-room type plasticity existing for existing high-temperature-room type plasticity magnesium alloy, or largely use a variety of rare earth elements Harshness is required with high-priced alloying element or processing technology, leads to problems such as cost excessively high, a kind of inexpensive high-temperature-room type plasticity is provided Wrought magnesium alloy and preparation method thereof.The alloy is a kind of novel Mg-Bi-Sn-Zr-Ca-Y alloy, on Mg-Bi alloy basis Upper introducing Sn element and micro Zr, Ca, Y element carry out polynary micro composite alloying, while controlling Bi element and Ca element Ratio avoids Mg₂The generation of Ca phase, in order to avoid the deterioration of alloy plasticity.In preparation method, the present invention needs in fusion process It is carried out under higher temperature (750 DEG C), casting process is protected without protective gas, can be with direct pouring under atmospheric atmosphere.This hair Bright extremely simple manufacturing process, so that it may obtain the wrought magnesium alloy of high-temperature-room type plasticity, room temperature elongation percentage reaches 35% More than, while raw material and low processing cost, it easily realizes and produces in enormous quantities.

The technical scheme is that

A kind of low cost high-temperature-room type plasticity wrought magnesium alloy, the alloy are Mg-Bi-Sn-Zr-Ca-Y alloy, chemistry at Divide mass percent are as follows: 2~5.0wt% of Bi；2~5.0wt% of Sn；0.5~1.2wt% of Zr；0.1~0.8wt% of Ca；Y 0.01~0.08wt%, remaining is Mg and inevitable impurity；Also, mass ratio Bi:Ca=6~7:1.

The preparation method of the inexpensive high-temperature-room type plasticity wrought magnesium alloy, comprising the following steps:

1) ingredient: to be closed among pure Mg ingot, pure Bi block, pure Sn block, Mg-Zr intermediate alloy, Mg-Ca intermediate alloy and Mg-Y Gold is raw material, carries out ingredient according to the magnesium alloy ingredient；

2) melting: pure Mg ingot is put into the crucible of smelting furnace, is set 700~730 DEG C of furnace temperature and is kept, to its fusing Afterwards, respectively by the pure Bi block for being preheating to 50~80 DEG C, pure Sn block, and be preheating to 100~150 DEG C Mg-Zr intermediate alloy, Mg-Ca intermediate alloy and Mg-Y intermediate alloy are added in magnesium melt；Then smelting temperature is increased to 750~780 DEG C, and is kept the temperature It to alloy melting, then stirs 3~10 minutes, high-purity Ar gas is passed through into melt and carries out refining degassing processing within 10~30 minutes； Control temperature is adjusted at 750 DEG C~760 DEG C, heat preservation stands 3~10 minutes；The above melting and heat preservation standing process are in CO₂/SF₆ Mixed gas protected lower progress；

3) it casts: the magnesium alloy fused mass after standing being poured into the mold for being preheating to 200~250 DEG C, as cast condition magnesium is made Alloy；Casting process is not necessarily to gas shield；

4) it is dissolved: solution treatment is carried out to obtained as-cast magnesium alloy, solid solution temperature is 460~500 DEG C, and the time is It 8~12 hours, is then quenched with 30~80 DEG C of warm water；The heating of solution treatment and insulating process are not necessarily to gas shield；

5) ingot casting after solution treatment that upper step obtains is cut into corresponding blank and removed the peel；

6) it is squeezed and deformed: after the blank that upper step obtains was heated to 270~400 DEG C within 20~30 minutes, being put into mould Deformation processing is carried out in tool；It carries out air-cooled after deformation processing, finally obtains the inexpensive high-temperature-room type plasticity wrought magnesium alloy Material.

The mold is for shaping stick, plate, pipe, line or the mold of profile.

Stirring in the step 2) is mechanical stirring or Argon gas agitating.

The Mg-Zr intermediate alloy is preferably Mg-30Zr intermediate alloy.

The Mg-Ca intermediate alloy is Mg-20Ca intermediate alloy.

The Mg-Y intermediate alloy is Mg-30Y intermediate alloy.

The CO₂And SF₆Mixed gas group become volume ratio be CO₂: SF₆=50~100:1.

Substantive distinguishing features of the invention are as follows:

Grain size in the plasticity and alloy of magnesium alloy, the type of the second phase, size, quantity are distributed, the texture in alloy Configuration is closely related.

Magnesium alloy of the invention passes through the control of Bi element and Ca constituent content ratio using Bi and Sn as main alloying elements System, can be formed in situ the Mg of high thermal stability in the alloy₂Bi₂Ca phase, Mg₃Bi₂Phase and Mg₂Sn phase, avoids Mg₂The life of Ca phase At simultaneously because the mutually competitive growth in process of setting of three kinds of alloys, can inhibit mutual size, on the one hand, avoid producing Raw the second phase of large scale reduces the damage to alloy plasticity, on the other hand the micron order Mg of appropriate high thermal stability₂Bi₂Ca phase exists It can be stabilized in heat treatment process, so in extrusion process, can promote dynamic recrystallization forming core, inhibit recrystal grain long Greatly, to improve the plastic deformation ability of alloy.In addition, can be with into Bi, Sn, Ca and Y element by being dissolved simultaneously in the alloy Change alloy axis ratio, and then change the mechanism of plastic deformation, so that the fibrous texture formed more under normal conditions and plate be avoided to knit Structure, and then be conducive to the promotion of alloy plasticity.Alloy is after solid solution, plastic processing, and stretch percentage elongation reaches under room temperature (25 DEG C) 35% or more.

Relatively uniform stabilization when alloy melting of the present invention, due to the fusing point (271.3 DEG C) of master alloying element Bi, Sn it is molten Point (231.89 DEG C) is lower, it is easy to keep alloy melt uniform, simultaneously because having Bi element, Ca element, Y element and other alloys Comprehensive function of the element in magnesium alloy fused mass has preferable fire retardation, and melt is also more stable, is being not higher than 760 DEG C Under the conditions of, casting can be completed in air atmosphere, can complete heat treatment in burner hearth nature atmosphere when being not higher than 450 DEG C, Show good flame retardant effect.

There was only trace rare-earth element in the novel high-strength magnesium alloy, cost is relatively low.Can be used as communications and transportation, aerospace, The components materials'use of computer, communication and consumer electronics product.

Compared with prior art, marked improvement of the invention and advantage are as follows:

1) magnesium alloy of the invention passes through simple alloying hand using Bi element and Sn element as main alloy element Section, forms a large amount of Mg₂Bi₂Ca phase, Mg₃Bi₂Phase and Mg₂Sn.Bi, Sn, Ca and Y into matrix are dissolved in subsequent heat treatment Element changes the axis ratio of matrix, and under extrusion process effect, synergistic effect improves the texture characteristic of deformation states alloy, while having again Part Mg₃Bi₂Phase and Mg₂Sn dynamic is precipitated with nanoscale, and then improves the temperature-room type plasticity of alloy, and room temperature elongation percentage can be with Reach 35% or more.

2) the nanoscale hardening constituent Mg in alloy of the present invention₃Bi₂Phase (823 DEG C) and Mg₂Sn phase (772 DEG C) and micron order Second phase Mg₂Bi₂Ca phase fusing point with higher, the incipient melting temperature of the second phase improves in alloy, allows alloy higher At a temperature of carry out thermal processing distortion, to reduce Deformation Resistance, improve processing or production efficiency.

3) alloy of the present invention shows preferable fire retardation during the preparation process, and melt is also more stable, is being not higher than 750 Under conditions of DEG C, casting can be completed in air atmosphere, can be completed at heat in burner hearth nature atmosphere when being not higher than 500 DEG C Reason, shows good flame retardant effect.

4) magnesium alloy of the present invention is free of any rare earth element and high-priced alloying element, and metal Bi and Sn is cheap, can drop Low-alloyed production cost (general 1000 to the 5000 yuan of per kilograms of rare earth, and metal Bi, Sn per kilogram used in this patent is only used 100-250 member or so)；

5) magnesium alloy preparation process of the present invention is simple, breaches large plastometric set required by most of high-strength magnesium alloys etc. The limitation of special processing method, existing magnesium alloy extrusion equipment all can carry out Continuous maching production to it, be not necessarily to additional improvement, Requirement to production equipment is low.

Detailed description of the invention

To make the objectives, technical solutions, and advantages of the present invention clearer, below in conjunction with attached drawing to the present invention do into The displaying of one step.

Fig. 1 is the tensile test at room temperature stress-strain diagram of embodiment 1,2,3 magnesium alloy and comparative example A's Z31 alloy；

Fig. 2 is the microscopic structure of alloy obtained in embodiment 1, wherein Fig. 2 a is low power microstructure；Fig. 2 b is high power Microstructure；

Fig. 3 is the microstructure picture of alloy obtained in embodiment 2；Wherein, Fig. 3 a is low power microstructure；Fig. 3 b is High power microstructure；

Fig. 4 is the TEM macrograph of alloy structure obtained in embodiment 2；

Fig. 5 is the alloy inverse pole figure that embodiment 2 obtains；

Fig. 6 is the microstructure picture of alloy obtained in embodiment 3；Wherein, Fig. 6 a is low power microstructure；Fig. 6 b is High power microstructure.

Specific embodiment

(technical solution) of the invention is described further below by specific embodiments and the drawings, following embodiment is equal Implemented under premised on technical solution of the present invention, the detailed implementation method and specific operation process are given, but this hair Bright protection scope is not limited to the following embodiments.

Choose three kinds of alloying component Mg-2.5Bi-2.5Sn-1Zr-0.4Ca-0.03Y (wt%) (alloy 1), Mg-3Bi- 3Sn-1Zr-0.5Ca-0.04Y (wt%) (alloy 2), Mg-4Bi-4Sn-1Zr-0.6Ca-0.05Y (wt%) (alloy 3) conduct Typical example.

Technical solution according to the invention, with pure Mg (99.8wt%) ingot, pure Bi (99wt%) block, pure Sn (99wt%) (the actually detected content of Ca is by block, Mg-30Zr (the actually detected content of Zr is 30.01wt%) intermediate alloy, Mg-20Ca 20.01wt%) intermediate alloy and Mg-30Y (the actually detected content of Y is 30.02wt%) intermediate alloy are alloyed feedstock, warp Low-cost magnesium alloy ingot casting is made in melting；Will by solution treatment, peeling, pre-extrusion and cooling rolling processing obtain invent and Gold.At room temperature (25 DEG C), Mechanics Performance Testing, embodiment and comparative example A's Z31 tensile property test result are carried out to extruded bars It is shown in Table 1.

Embodiment 1

(1) design is chosen Mg-2.5Bi-2.5Sn-1Zr-0.4Ca-0.03Y (wt%) alloying component and is matched into magnesium alloy, Preparation method the following steps are included:

1) ingredient: with pure Mg (99.8wt%) ingot, pure Bi (99wt%) block, pure Sn (99wt%) block, Mg-30Zr, Mg- 20Ca and Mg-30Y intermediate alloy is raw material, (such as removal dirt, oxide skin etc., following embodiment after surface preparation Together), ingredient is carried out by above-mentioned target component；Wherein, mass ratio Bi:Ca=6.25:1.

2) melting: clearing up crucible and preheat, and the magnesium ingot for being preheating to 200 DEG C is put into the crucible of smelting furnace, sets furnace 720 DEG C of temperature, slow heating, heating rate are 25 DEG C/min.After it melts, it will successively be preheating to 50 DEG C of pure Bi block, pure Sn Block, pure Zn block and it is preheating to 200 DEG C of Mg-30Zr, Mg-20Ca intermediate alloy and Mg-30Y intermediate alloy is added to magnesium melt In；Smelting temperature is increased to 750 DEG C, 30 minutes is kept the temperature, is completely melt alloy, then stirs 5 minutes, height is passed through into melt Pure Ar gas (purity 99.999%) carries out refining degassing processing 2 minutes, then heat preservation stands 5 minutes at 750 DEG C；The above melting and Keeping the temperature standing process is CO in volume ratio₂: SF₆The CO of=100:1₂: SF₆Mixed gas protected lower progress；

3) it casts: the magnesium alloy fused mass after standing being poured into the cylindrical metal mold that diameter is 60mm, before casting Mold is preheating to 250 DEG C, and 750 DEG C of cast temperature, as-cast magnesium alloy is made；Casting process is not necessarily to gas shield；

4) Homogenization Treatments: carrying out solution treatment to obtained as-cast magnesium alloy, and solid solution temperature is 480 DEG C, the time It is 10 hours, 50 DEG C of warm water quenchings；The heating of solution treatment and insulating process are not necessarily to gas shield；

5) machine: turnery processing removes the oxide layer on alloy cast ingot surface obtained by step 4), and is processed into suitable extruding The size of processing；

6) deformation processing: with extruder by alloy extrusion obtained by step 5) at bar, main technologic parameters when extruding: blank 280 DEG C of temperature, 280 DEG C of extrusion cylinder temperature, 280 DEG C of mold temperature, extrusion speed 5m/min, extrusion ratio 25 adds deformation blank Heat 30 minutes squeezes 280 DEG C of temperature needed for reaching, squeeze wood uses air-cooled cooling.

(2) alloy performance test and Analysis on Microstructure

It is sampled from gained alloy, is processed into coupon, carrying out tensile tests at room, (this experiment test uses GB/T 228.1-2010 the room temperature test method in metal material stretching test.Following embodiment is all made of the method), the embodiment institute Magnesium alloy Typical tensile curve it is as shown in fig. 1, measure gained alloy tensile strength reach 222.7MPa, yield strength reaches To 157.7MPa, elongation percentage 44.3%.(table 1).Fig. 2 is Mg-2.5Bi-2.5Sn-1Zr-0.4Ca- obtained by the present embodiment The displaing micro tissue topography of 0.03Y (wt%) magnesium alloy organizes as can be seen that perfect recrystallization has occurred in alloy from Fig. 2 (a) In there is a small amount of the second phase of micron order to be randomly dispersed on matrix, these second phases are mainly higher melting-point Mg₂CaBi₂Phase, can be with Promote alloy that dynamic recrystallization occurs in extrusion process；Such as Fig. 2 (b) it can be seen that dynamic recrystallization crystallite dimension is at 8-30 μm Left and right, in addition, with the presence of tiny precipitated phase in alloy, these precipitated phases are to be dissolved Bi element in the base and Sn element exists The Mg that Dynamic Precipitation generates occurs in extrusion process₃Bi₂Phase and Mg₂Sn phase, these nanometer precipitated phases can inhibit alloy in room temperature Twin generation in advance in deformation process, and then improve alloy plasticity.

Embodiment 2

(1) design chooses Mg-3Bi-3Sn-1Zr-0.5Ca-0.04Y (wt%) alloying component proportion into magnesium alloy, preparation Method the following steps are included:

1) ingredient: with pure Mg (99.8wt%) ingot, pure Bi (99wt%) block, pure Sn (99wt%) block, Mg-30Zr, Mg- 20Ca and Mg-30Y intermediate alloy is raw material, (such as removal dirt, oxide skin etc., following embodiment after surface preparation Together), ingredient is carried out by above-mentioned target component；Mass ratio Bi:Ca=6:1.

2) melting: clearing up crucible and preheat, and the magnesium ingot for being preheating to 200 DEG C is put into the crucible of smelting furnace, sets furnace 720 DEG C of temperature, slow heating, heating rate are 25 DEG C/min.After it melts, it will successively be preheating to 50 DEG C of pure Bi block, pure Sn Block, pure Zn block and it is preheating to 200 DEG C of Mg-30Zr, Mg-20Ca intermediate alloy and Mg-30Y intermediate alloy is added to magnesium melt In；Smelting temperature is increased to 750 DEG C, 30 minutes is kept the temperature, is completely melt alloy, then stirs 5 minutes, height is passed through into melt Pure Ar gas carries out refining degassing processing 2 minutes, then melting in heat preservation standing 5 minutes or more and heat preservation standing process are equal at 750 DEG C It is CO in volume ratio₂: SF₆The CO of=100:1₂: SF₆Mixed gas protected lower progress；

(2) alloy performance test and Analysis on Microstructure

It is sampled from gained alloy, is processed into coupon, carry out tensile tests at room, magnesium alloy typical case obtained by the embodiment draws Stretch that curve is as shown in fig. 1, the tensile strength for measuring gained alloy reaches 238.3MPa, and yield strength reaches 176MPa, extends Rate 39.1%.(table 1).Fig. 3 is Mg-3Bi-3Sn-1Zr-0.5Ca-0.04Y (wt%) magnesium alloy obtained by the present embodiment There is a small amount of the second phase of micron order in displaing micro tissue topography as can be seen that perfect recrystallization has occurred in alloy from Fig. 3 (a) in tissue It is randomly dispersed on matrix, these second phases are mainly higher melting-point Mg₂CaBi₂Phase can promote alloy in extrusion process Dynamic recrystallization occurs；Such as Fig. 3 (b) it can be seen that dynamic recrystallization crystallite dimension is at 25 μm or so, in addition, having in alloy tiny Precipitated phase exist, these precipitated phases be to be dissolved Bi element in the base and Dynamic Precipitation occurs in extrusion process for Sn element The Mg of generation₃Bi₂Phase and Mg₂Sn phase, these nanometer precipitated phases can inhibit alloy during deformation at room temperature it is twin in advance Occur, and then improves alloy plasticity.To further look at its Dynamic Precipitation situation, the TEM for being illustrated in figure 4 alloy 2 is organized, from In it can be seen that the micron order precipitated phase for having a large amount of sizes not equal in alloy and tiny nanoscale Dynamic Precipitation phase, with figure 3 observation results are consistent.Fig. 5 is 2 inverse pole figure of alloy, it can be seen that occurs non-basal plane texture, and the intensity of texture in alloy It is lower, show that alloy of the present invention breaches the constraint that conventional alloys generate basal plane texture after squeezing, can greatly improve conjunction Golden temperature-room type plasticity.

Embodiment 3

(1) design chooses Mg-4Bi-4Sn-1Zr-0.6Ca-0.05Y (wt%) alloying component proportion into magnesium alloy, preparation Method the following steps are included:

1) ingredient: with pure Mg (99.8wt%) ingot, pure Bi (99wt%) block, pure Sn (99wt%) block, Mg-30Zr, Mg- 20Ca and Mg-30Y intermediate alloy is raw material, (such as removal dirt, oxide skin etc., following embodiment after surface preparation Together), ingredient is carried out by above-mentioned target component；Mass ratio Bi:Ca=6.67:1.

(2) alloy performance test and Analysis on Microstructure

It is sampled from gained alloy, is processed into coupon, carry out tensile tests at room, magnesium alloy typical case obtained by the embodiment draws Stretch that curve is as shown in fig. 1, the tensile strength for measuring gained alloy reaches 246.7MPa, and yield strength reaches 188.4MPa, prolongs Stretch rate 35.7%.(table 1).Fig. 6 is Mg-4Bi-4Sn-1Zr-0.6Ca-0.05Y (wt%) magnesium alloy obtained by the present embodiment Displaing micro tissue topography, from Fig. 6 (a) as can be seen that alloy perfect recrystallization has occurred, have a small amount of micron order second in tissue It is mutually randomly dispersed on matrix, these second phases are mainly higher melting-point Mg₂CaBi₂Phase can promote to close in extrusion process Golden hair gives birth to dynamic recrystallization；Such as Fig. 6 (b) it can be seen that dynamic recrystallization crystallite dimension is at 28 μm or so, in addition, having in alloy thin Small precipitated phase exists, these precipitated phases be that dynamically analysis occurs in extrusion process for solid solution Bi element in the base and Sn element The Mg generated out₃Bi₂Phase and Mg₂Sn phase, these nanometer precipitated phases can inhibit twin during deformation at room temperature of alloy to mention Preceding generation, and then improve alloy plasticity.From Fig. 6 (a) and (b) as can be seen that the embodiment alloy microstructure and embodiment 1 are closed Gold is similar with 2 alloy microstructure of embodiment.

In summary, alloy of the invention, 1. by introduced on the basis of Mg-Bi alloy Sn element and micro Zr, Ca, Y element carry out polynary micro composite alloying, form texture (structure) configuration with non-basal plane texture in the alloy, Prepare the excellent alloy material of temperature-room type plasticity.2. the content and ratio of Bi element and Ca element have certain in alloy of the present invention Limitation controls between 7:1 and 6:1, avoids Mg₂The generation of Ca phase, in order to avoid the deterioration of alloy plasticity.

In terms of alloy preparation method, for alloy of the present invention 1. in casting and heat treatment process, the present invention is not necessarily to protective gas Protection, can be with direct pouring under atmospheric atmosphere, other magnesium alloys need to be poured under vacuum or protective gas protection mostly Casting and heat treatment；This point is also the performance that alloy has certain flame retardant property.2. needing in fusion process in higher temperature Melting and heat preservation are carried out under (750 DEG C).

Comparative example

The current commercial magnesium alloy of selection, AZ31 magnesium alloy, ingredient: Mg-2.9Al-0.75Zn-0.3Mn (wt%) conduct pair Ratio.The stresses typical strain curve such as Fig. 1 of comparative example (being obtained under processing conditions same as Example 2) in tension test It is shown.Its tensile strength is 223.7MPa, and yield strength 203.5MPa, elongation percentage is 20.2% (table 1).

As it can be seen that novel magnesium alloy elongation percentage of the invention is close with comparative example, tension and yield strength are obtained greatly for comparison Degree improves, and substantially exceeds the intensity of commercial high-strength magnesium alloy at present, reaches and largely adds rare earth element and Li mischmetal Similar effect is a kind of novel Room Temperature high plastic magnesium alloy for having very much the market competitiveness.This is mainly due to alloy texture Change and nanometer precipitated phase presence, coefficient result.

The room-temperature mechanical property test result of 1 embodiment of table and comparative example

Raw material used in above-described embodiment and equipment pass through well known approach and obtain, and operating procedure used is this What those skilled in the art can grasp.

Unaccomplished matter of the present invention is well-known technique.

Claims

1. a low-cost high room temperature plastic deformation magnesium alloy, it is characterized in that this alloy is Mg-Bi-Sn-Zr-Ca-Y alloy, and its chemical composition mass percentage is: Bi 2～5.0wt%; Sn 2～5.0 wt%; Zr 0.5-1.2wt%; Ca 0.1-0.8wt%; Y 0.01-0.08wt%, the rest are Mg and inevitable impurities; and the mass ratio Bi:Ca=6-7:1.

2. the preparation method of the low-cost high room temperature plastic deformation magnesium alloy as claimed in claim 1 is characterized in that the method comprises the following steps:

1) batching: take pure Mg ingot, pure Bi block, pure Sn block, Mg-Zr master alloy, Mg-Ca master alloy and Mg-Y master alloy as raw materials, and carry out batching according to the described magnesium alloy composition;

2) Smelting: put the pure Mg ingot into the crucible of the melting furnace, set the furnace temperature to 700-730 ℃ and keep it, after it is melted, respectively preheat the pure Bi block and pure Sn block to 50-80 ℃, And the Mg-Zr master alloy, Mg-Ca master alloy and Mg-Y master alloy preheated to 100-150 ℃ are added to the magnesium melt; then the melting temperature is raised to 750-780 ℃, and kept for 10-30 minutes Until the alloy is melted, stir for 3 to 10 minutes, and pass high-purity Ar gas into the melt for refining and degassing; adjust and control the temperature at 750°C to 760°C, keep it at rest for 3 to 10 minutes; The setting process is carried out under the protection of CO ₂ /SF ₆ mixed gas;

3) Casting: pour the standing magnesium alloy melt into a mold preheated to 200-250°C to obtain as-cast magnesium alloy; the casting process does not require gas protection;

4) Solid solution: the obtained as-cast magnesium alloy is subjected to solid solution treatment, the solution treatment temperature is 460-500 ℃, the time is 8-12 hours, and then quenched with warm water at 30-80 ℃; the heating and heat preservation of the solution treatment The process does not need gas protection;

5) the solution-treated ingot obtained in the previous step is cut into corresponding billets and peeled;

6) Extrusion deformation: heat the billet obtained in the previous step to 270 to 400° C. within 20 to 30 minutes, and then put it into a mold for deformation processing; after the deformation processing, carry out air cooling, and finally obtain the low cost and high room temperature. Plastic deformable magnesium alloy material.

3. The preparation method of low-cost high room temperature plastically deformed magnesium alloy as claimed in claim 2, characterized in that the mould described in the method is a mould for forming rods, plates, tubes, wires or profiles.

4. The preparation method of low-cost high room temperature plastically deformed magnesium alloy as claimed in claim 2, characterized in that the stirring in the step 2) is mechanical stirring or stirring by blowing argon gas.

5. The preparation method of low-cost high room temperature plastically deformed magnesium alloy as claimed in claim 2, wherein the Mg-Zr master alloy is a Mg-30Zr master alloy.

6. The preparation method of low-cost high room temperature plastically deformed magnesium alloy as claimed in claim 2, characterized in that the Mg-Ca master alloy is a Mg-20Ca master alloy.

7. The preparation method of low-cost high room temperature plastically deformed magnesium alloy as claimed in claim 2, wherein the Mg-Y master alloy is a Mg-30Y master alloy.

8 . The method for preparing low-cost and high-room temperature plastically deformed magnesium alloys according to claim 2 , wherein the mixed gas of CO ₂ and SF ₆ is composed of a volume ratio of CO ₂ : SF ₆ =50～100. 9 . :1.