CN102230117A - 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

But magnesium alloy is the lightest in the present industrial application structure metallic substance, under equal volume, magnesium alloy is lighter by 36% than aluminium alloy, 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 magnesium alloy on automobile receive great concern.Mg-Al base alloy (as AZ91 and AM60 etc.) is the present industrial magnesium alloy series that is most widely used, and in this series magnesium alloy, its strengthening phase is Mg ₁₇A ₁₂, this class 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 is the Mg of net distribution on crystal boundary when temperature surpasses 120 ℃ 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 magnesium alloy performance.In magnesium alloy, add rare earth element (as Y, Nd, Yb etc.), alkaline earth element has caused great concern, and add and not reduce other performances when rare earth element 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 magnesium alloy, Ca has the effect of good crystal grain thinning in Mg-Al base alloy, and forms Laves phase Mg by eutectic reaction in matrix 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) magnesium alloy performance impact to add Nd up to now, the rare especially report of the performance study of AX62-xNd magnesium alloy behind overheating deforming.

Technical scheme

The purpose of this invention is to provide a kind of rare earth neodymium that adds to magnesium-aluminium-calcium wrought magnesium alloys and improve the preparation method of its performance, the interpolation rare earth neodymium that adopts the inventive method preparation is to magnesium-aluminium-calcium wrought magnesium alloys, when improving magnesium alloy tensile strength, also improved its yield strength.Preparation method of the present 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 described 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.

Magnesium alloy of the present 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 magnesium alloy.

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.Tiny through the alloy structure after the hot extrusion, and separate 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 rare earth element is resolved, and simultaneously, the alloy structure that obtains is tiny, and tensile strength, the yield strength of alloy material all had good improvement effect.Preparation 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 magnesium alloy microstructure that present gravity casting method prepares by 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 pushing, 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 yield strength 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, can improve only about 3.7% than the tensile strength maximum of not adding the Nd mischmetal, 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 magnesium alloy 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 described magnesium alloy (Mg-6Al-2Ca alloy);

Fig. 2 is the XRD figure spectrum of embodiment 4 described magnesium alloy;

Fig. 3 is the cross section metallograph of the described magnesium alloy 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 described magnesium alloy 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 magnesium alloy.

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 of the present invention respectively, the preparation work before the preparation alloy comprises: the raw-material surface of polishing, is inserted starting material in the Steel Crucible that is enclosed within the plumbago crucible to remove the oxide skin of material surface to bright.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 magnesium alloy 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 the experiment 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%) magnesium alloy.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.

As shown in Figure 1 and 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 is offset to Small angle after adding, and this has illustrated 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 cross section metallograph of magnesium alloy.As seen from the 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 magnesium alloy.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 magnesium alloy, and table 1 is the ambient temperature mechanical properties data of extruding attitude AX62-xNd magnesium alloy.The interpreting blueprints 5 and table 1 as can be known, along with increasing of rare earth Nd addition, tensile strength of alloys and yield strength constantly increase, maximum value can reach 319MPa and 210MPa respectively; Unit elongation presents 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 magnesium alloy.

Table 1

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

Claims (3)

1. magnesium-aluminium-calcium the wrought magnesium alloys that contains 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.

2. magnesium-aluminium-calcium the wrought magnesium alloys that contains rare earth neodymium according to claim 1 is characterized in that the mass percent of described wrought magnesium alloys each component is:

Al content is 6%;

Ca content is 2%;

Nd content is 0.9～4.0%;

Surplus is Mg.

3. the preparation method of the arbitrary described wrought magnesium alloys of claim 1-2 is characterized in that following steps are arranged:

1). according to the described each component raw material of getting of claim 1, 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 25: 1 the condition, obtains containing the magnesium-aluminium-calcium wrought magnesium alloys of rare earth neodymium.

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