CN102230117B - Magnesium-aluminium-calcium wrought magnesium alloy with rare earth neodymium and preparation method thereof - Google Patents

Abstract

The invention relates to a magnesium-aluminium-calcium wrought magnesium alloy with rare earth neodymium and a preparation method thereof. The wrought magnesium alloy comprises the following components by mass: 5.5-6.2% of Al; 1.8-2.1% of Ca; 0.9-4.0% of Nd; and the balance Mg. Prepared by the method of the invention, the magnesium-aluminium-calcium wrought magnesium alloy with rare earth neodymium has strengthened tensile strength and yield strength. With low cost of equipment, the preparation method provided in the invention is simple and easy to be implemented.

Description

A kind of magnesium-aluminium-calcium wrought magnesium alloys that contains rare earth neodymium and preparation method thereof

Technical field

The present invention relates to a kind of metallic substance, particularly a kind of magnesium-aluminium-calcium wrought magnesium alloys that contains rare earth neodymium and preparation method thereof.

Background technology

Magnesiumalloy is that but industry is gone up in the application structure metallic substance the lightest at present; Under equal volume; Magnesiumalloy is lighter by 36% than duraluminum; Lighter by 77% than steel, its low density, high specific strength, high specific stiffness, excellent machining property and advantages of good casting make it be widely used in fields such as automobile and aviations, and owing to environmental protection, requirements such as lightweight energy-conservation and automobile make the application of magnesiumalloy on automobile receive great concern.Mg-Al base alloy (like AZ91 and AM60 etc.) is that application magnesiumalloy series is the most widely gone up in industry at present, and in this series magnesium alloy, its strengthening phase is Mg ₁₇A ₁₂, this type alloy has advantages of good casting and ambient temperature mechanical properties preferably, but itself exists the shortcoming that is difficult to overcome: the form with divorced eutectic is the netted thick Mg that separates out along crystal boundary ₁₇Al ₁₂Phase makes the plasticity and the strength degradation of cast alloy, and when temperature surpasses 120 ℃, is the Mg of net distribution on crystal boundary ₁₇Al ₁₂Phase is easy to softening and thickization, seriously reduces the intensity of alloy.

Adding alloying element is one of effective way that effectively improves the magnesiumalloy performance.In magnesiumalloy, add REE (like Y, Nd, Yb etc.), alkaline earth element has caused great concern, and add and not reduce other performances when REE can significantly improve alloy mechanical performance.Ca is because advantages such as the cheap and low density of its aboundresources are extensively added to antioxidant property, the mechanical property that improves alloy in the magnesiumalloy; Ca has the effect of good crystal grain thinning in Mg-Al base alloy, and in matrix, forms Laves phase Mg through eutectic reaction in the process of alloy graining ₂Ca suppresses Mg ₁₇Al ₁₂The formation of phase and reach and improve alloy mechanical performance.At present; Existing traditional method preparation AX53 (Mg-5Al-3Ca alloy) as-cast magnesium alloy; The alloy microscopic structure that this method makes is thick; Performance to alloy is unfavorable, and it is rarely seen to the report of AX62 (Mg-6Al-2Ca alloy) magnesiumalloy performance impact to add Nd up to now, the rare especially report of the performance study of AX62-xNd magnesiumalloy behind overheating deforming.

Technical scheme

The purpose of this invention is to provide a kind of preparation method who adds in rare earth neodymium to magnesium-aluminium-calcium wrought magnesium alloys and improve its performance; Adopt interpolation rare earth neodymium to the magnesium-aluminium-calcium wrought magnesium alloys of the inventive method preparation; When improving magnesiumalloy tensile strength, also improved its ys.Preparing method according to the invention is simple, and equipment cost is low, implements easily.

Technical scheme of the present invention is: contain the magnesium-aluminium-calcium wrought magnesium alloys of rare earth neodymium, comprise Al, Ca, Nd, the quality percentage composition of each component is:

Al content is 5.5～6.2%;

Ca content is 1.8～2.1%;

Nd content is 0.9～4.0%;

Surplus is Mg.

The better technical scheme of said wrought magnesium alloys is that the mass percent of each component is:

Al content is 6%;

Ca content is 2%;

Nd content is 0.9～4.0%

Surplus is Mg.

Magnesiumalloy according to the invention is also to contain unavoidable impurities, its total content≤0.15%, and its unavoidable impurities is Fe, Zn, Cu, the mass percent of its each component is: Fe content≤0.02%, Zn content≤0.015%, Cu content≤0.015%.

The preparation method of above-mentioned wrought magnesium alloys has following steps:

1). get the each component raw material according to said ratio, put into container, the container that is loaded with the each component raw material is put into vacuum induction furnace, melting under the argon shield;

2). after treating that alloy all melts, insulation 5min;

3). take out the container that fills alloy liquid, put into the fast cold 1-2 of brine bath minute, obtain the alloy spindle;

4). alloy spindle air cooling behind 480 ℃ of following insulation annealing 8h that step 3) is obtained; 330 ℃, extrusion ratio is to carry out hot extrusion under 25: 1 the condition, obtains containing the magnesium-aluminium-calcium wrought magnesium alloys of rare earth neodymium.

Nd unit have and improves alloy casting performance, crystal grain thinning, improves advantages such as alloy antioxidant property, and China's rare earth resources is abundant, so Nd is widely used in magnesiumalloy.

The alloy that adopts the inventive method to prepare, a part of rare earth Nd solid solution is in α-Mg, and another part rare earth atom Nd reacts with the Al atom and separates out with intermetallic compound Al-Nd form mutually.Alloy structure through after the hot extrusion is tiny, and separates out the compound disperse and be distributed in the matrix.Improvement to alloy property mainly contains three kinds of strengthening mechanisms: one, refined crystalline strengthening, two, solution strengthening, three, second strengthens mutually.When grain-size reduces, resistance to deformation power is increased, played the refined crystalline strengthening effect; Rare earth element nd is solid-solubilized in α-Mg matrix, because the Young's modulus and the atomic radius of solute and matrix element are different, makes matrix produce certain lattice distortion, and consequent stress field will hinder the motion of dislocation, thereby improve alloy strength; In addition, be distributed in the motion that crystal boundary or dendrite gap intermediary Al-Nd compound hinder dislocation, thereby play strengthening effect, and then improve alloy strength.The present invention adopts brine bath cold soon, because speed of cooling is fast, the segregation problem of REE is resolved, and simultaneously, the alloy structure that obtains is tiny, and tensile strength, the ys of alloy material all had good improvement effect.Preparing method of the present invention has following advantage:

1. implement easily, cost is low, energy consumption weak point little and consuming time;

2. to compare the magnesiumalloy microstructure that present gravity casting method prepares through the fast cold alloy microscopic structure that obtains of salt bath tiny in the present invention, and segregation improves;

3. the bar-shaped alloy product that obtains after the extruding, mechanical property is improved.Than traditional gravity casting as cast condition Mg-5Al-3Ca-xNd (x=0,1,2,3) alloy, the tensile strength maximum can improve 28%, and the ys maximum can improve about 98.1%;

4. after the alloy that preparation method of the present invention obtains added the rare earth Nd element, the effect of improving alloy property was more obvious; After traditional gravity casting cast alloy adds the rare earth Nd element; Tensile strength maximum than not adding the Nd mischmetal can improve only about 3.7%; After the extruding attitude alloy that the present invention obtains adds the rare earth Nd element, improve about 31% than the tensile strength of not adding the Nd mischmetal is maximum.

5. prepare magnesiumalloy with traditional gravity casting method and compare, the present invention is simple to operate, need not prepare casting mold, thereby reduces preparation cost.

The starting material that use when magnesium alloy materials of the present invention prepares are: its content of high pure magnesium ingot is＞99.9% (mass percent; Down together); Its content of fine aluminium ingot is＞99.9%, and its content of Mg-30Ca master alloy is 30% calcium, and its content of Mg-30Nd master alloy is 30% neodymium.

Description of drawings

Fig. 1 is the XRD figure spectrum of embodiment 1 said magnesiumalloy (Mg-6Al-2Ca alloy);

Fig. 2 is the XRD figure spectrum of embodiment 4 said magnesiumalloy;

Fig. 3 is the xsect metallograph of the said magnesiumalloy of extruding attitude embodiment 1-5, and wherein (a) is embodiment 1; (b) be embodiment 2; (c) be embodiment 3; (d) be embodiment 4; (e) be embodiment 5;

Fig. 4 is the metallograph along the direction of extrusion of the said magnesiumalloy of extruding attitude embodiment 1-5, and wherein (a) is embodiment 1; (b) be embodiment 2; (c) be embodiment 3; (d) be embodiment 4; (e) be embodiment 5;

Fig. 5 is the ambient temperature mechanical properties figure of extruding attitude embodiment 1-5 magnesiumalloy.

Embodiment

Embodiment

	Al	Ca	Nd	Mg
					Embodiment 1	6	2	-	92
Embodiment 2	6	2	1	91
					Embodiment 3	6	2	2	90
Embodiment 4	6	2	3	89
					Embodiment 5	6	2	4	88
Embodiment 6	5.5	1.8	2	90.7
					Embodiment 7	6.5	2.1	4	89.4

According to the proportioning of embodiment 1-7, get starting material according to the invention respectively, the preparation work before the preparation alloy comprises: raw-material surface to the light of polishing is inserted starting material in the Steel Crucible that is enclosed within the plumbago crucible to remove the oxide debris of material surface.Raw-material plumbago crucible will be housed put into vacuum induction furnace, and vacuumize in the fusion process and fill, to prevent the oxidation of magnesiumalloy with argon shield.Alloy in crucible all melts, and behind the insulation 5min, the Steel Crucible that alloy solution is housed is put into the fast cold-forming of salt solution obtain the alloy spindle.

With the fast cold alloy spindle that obtains air cooling behind 480 ℃ of following insulation annealing 8h; Then at 330 ℃, extrusion ratio is to carry out hot extrusion under 25: 1 the condition, obtains experiment and uses alloy material.

Obtain the alloy (embodiment 1-5) of different rare earth Nd content with identical prepared, i.e. AX62-xNd (x=0%, 1%, 2%, 3%, 4%) magnesiumalloy.The alloy material that makes is carried out microstructure observation with employing Zeiss Axiovert40 MAT metaloscope and employing thinks carefully that CMT-5105 microcomputer control electronics universal testing machine carries out the mechanical property of tension test beta alloy.

Like Fig. 1, shown in Figure 2, since the interpolation of rare earth Nd, the Mg among the alloy A X62 ₂Ca reaches Mg mutually ₁₇Al ₁₂Be suppressed mutually,, and cenotype Al is arranged ₂Ca and Al-Nd compound generate.And rare earth Nd has caused that α-Mg diffraction peak squints to maller angle after adding, and this has explained that the solid solution of Nd atomic component in α-Mg matrix, causes lattice distortion.

Fig. 3 for extruding attitude embodiment 1-5 (Nd=0%, 1%, 2%, 3%, 4%, down with) the xsect metallograph of magnesiumalloy.Visible by figure, along with the increase of rare earth Nd addition, alloy organizing obtains refinement, and precipitate quantity increases and the distribution disperse.

Fig. 4 is the metallograph along the direction of extrusion of extruding attitude embodiment 1-5 magnesiumalloy.Be illustrated as along the direction of extrusion, separate out and be zonal arrangement, and alloy grain is for waiting shape.

Fig. 5 is the ambient temperature mechanical properties figure of extruding attitude embodiment 1-5 magnesiumalloy, and table 1 is the ambient temperature mechanical properties data of extruding attitude AX62-xNd magnesiumalloy.Interpreting blueprints 5 and table 1 can know that along with increasing of rare earth Nd addition, tensile strength of alloys and ys constantly increase, and peak can reach 319MPa and 210MPa respectively; Unit elongation appears to reduce earlier afterwards increases the trend that reduces again.

Table 1 is the ambient temperature mechanical properties data of extruding attitude embodiment 1-5 magnesiumalloy.

Table 1

The above results shows, the microstructure that the present invention can effectively refinement target AX62-xNd magnesiumalloy, and the REE segregation problem that runs in the solution alloy melting process has been improved tensile strength of alloys, ys and unit elongation etc.

Claims (1)

1. a preparation method who contains the magnesium-aluminium-calcium wrought magnesium alloys of rare earth neodymium is characterized in that wrought magnesium alloys comprises Al, Ca, Nd, and the quality percentage composition of each component is: Al content is 5.5～6.2%; Ca content is 1.8～2.1%; Nd content is 0.9～4.0%; Surplus is Mg, and its preparation method has following steps:

1). according to the above-mentioned each component raw material of getting, put into container, container is put into vacuum induction furnace, melting under the argon shield;

2). after treating that alloy all melts, insulation 5min;

3). take out the container that fills alloy liquid, put into the fast cold 1-2 of brine bath minute, obtain the alloy spindle;

4). alloy spindle air cooling behind 480 ℃ of following insulation annealing 8h that step 3) is obtained; 330 ℃, extrusion ratio is to carry out hot extrusion under the condition of 25:1, obtains containing the magnesium-aluminium-calcium wrought magnesium alloys of rare earth neodymium.

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