CN100567538C - A kind of Nd heat resistance magnesium alloy and preparation method thereof that contains - Google Patents

Abstract

A kind of Nd of containing heat resistance magnesium alloy and preparation method thereof belongs to the heatproof magnesium alloy material field.The Nd heat resistance magnesium alloy that contains provided by the present invention, each component and mass percent thereof are: Al content is 5.5～6.5%, Nd content is 3.5～6.5%, impurity element Si content≤0.02%, Fe content≤0.005%, Cu content≤0.015%, Ni content≤0.002%, surplus are Mg.The present invention joins in 200～250 ℃ the crucible by magnesium alloy smelting insulating covering agent, magnesium ingot and the aluminium ingot that will be preheated to 140～160 ℃, add the Mg-Nd master alloy when treating that liquation is warming up to 750～780 ℃ through stirring, skim behind Mg-Al-Nd alloy liquid surface scum and the insulating covering agent liquation to be watered cast from and make in the metal pattern.Alloy of the present invention has higher high temperature strength and creep-resistant property.

Description

A kind of Nd heat resistance magnesium alloy and preparation method thereof that contains

Technical field

The invention belongs to the heatproof magnesium alloy material field, be specifically related to composition design of a kind of Nd of containing heat resistance magnesium alloy and preparation method thereof.

Background technology

Magnesium alloy is as the lightest structural metallic materials, has high specific tenacity and specific rigidity, good castability and machining property, is described as " the green structured material of 21 century ", has a wide range of applications.But the magnesium alloy of common designations commonly used, AZ91 for example is because its main strengthening phase Mg ₁₇Al ₁₂Fusing point only is 438 ℃, and strengthening phase is easily softening when being higher than 100 ℃ of environment uses, thereby causes the alloy high-temp strength degradation, has limited its range of application.

The upsurge [A.A.Luo.Inter.Mate.Rev.2004,49:14] of adding rare earth and preparing heat resistance magnesium alloy had appearred adopting in recent years.As the AE42 alloy,, the RE element that adds generated the Al of high-temperature stable because combining with Al ₁₁RE ₃Phase has effectively suppressed Mg ₁₇Al ₁₂Separate out, its creep-resistant property is improved greatly.Rare earth element nd also is considered to one of effective element that improves Mg-Al alloy resistance toheat, and its strengthening effect that is in the news is better than La, rare earth elements such as Ce [Z.P.Luo, S.Q.Zhang, L.Q.Lu, G.Wei, J.Rare Earths.1994; 4:296].About being to add rare earth element nd in the alloy and prepare high-performance magnesium-alloy some reports are also arranged to Mg-Al.As, high big vast we people adds 1.2mass%Nd and becomes Al in the Mg-6%Al alloy ₂The strengthening phase of high thermal stabilities such as Nd and improve its performance [Gao Hongwu, Hu Xiaoju, Li Changmao, Liu Liming, Liu Shunhua, the casting, 2005,54 (12): 1269]; People such as Huang Xiaofeng add 0.3-0.9mass%Nd and improve its resistance toheat in Mg-5Al-Si.But in the above research, the addition of Nd is the highest also only about 1.0mass%, can not the oversaturated solid solution aluminium of completely consumed, to such an extent as in creep process, still can separate out softening phase Mg ₁₇Al ₁₂, and cause the reduction of alloy resistance toheat.In order to reduce the Mg that separates out in the creep process ₁₇Al ₁₂Phase is necessary further to improve the addition of Nd very much.

Summary of the invention

The objective of the invention is to solve the deficiencies in the prior art, provide a kind of high-temperature heat-resistance well behaved high Nd content (heat resistance magnesium alloy of 3.5～6.5wt.%) and preparation method thereof.

A kind of Nd heat resistance magnesium alloy that contains provided by the present invention, each component and mass percent thereof are: Al content is 5.5～6.5%, Nd content is 3.5～6.5%, impurity element Si content≤0.02%, Fe content≤0.005%, Cu content≤0.015%, Ni content≤0.002%, Mg are balanced contents.

A kind of preparation method who contains the Nd heat resistance magnesium alloy provided by the present invention may further comprise the steps:

1) with magnesium ingot, aluminium ingot, Mg-Nd master alloy according to target in the alloy weight percent of component get the raw materials ready, and in baking oven, be preheated to 140～160 ℃;

2) the magnesium alloy smelting insulating covering agent is preheated to 140～160 ℃ in baking oven, magnesium alloy smelting insulating covering agent consumption and target alloy total mass ratio are 1/200～1/50;

3) crucible oven is set Heating temperature and is decided to be 780 ℃, when crucible temperature rises to 200～250 ℃, in crucible, be sprinkled into step 2) in the magnesium alloy smelting insulating covering agent of preheating, and add the magnesium ingot and the aluminium ingot of preheating in the step 1), obtain Mg-Al alloy liquation;

When 4) treating that Mg-Al alloy melt temperature rises to 750～780 ℃, the Mg-Nd master alloy that adds preheating in the step 1), obtain Mg-Al-Nd alloy liquation, and under this constant temperature Mg-Al-Nd alloy liquation was stirred 2～5 minutes, insulation was 30 minutes after stirring was finished;

5) Mg-Al-Nd alloy melt temperature is adjusted to 710～730 ℃, leave standstill 3～5 minutes after, skim Mg-Al-Nd alloy molten surface scum silica frost and magnesium alloy smelting insulating covering agent, Mg-Al-Nd alloy liquation be cast in to make in the metal pattern contain the Nd heat resistance magnesium alloy.

Wherein, the component of described magnesium alloy smelting insulating covering agent and mass percent thereof are: KCl (purity 99.9%) content is 55～65%, and LiCl (purity 99.9%) content is 10～15% and CaCl ₂Content (purity 99.9%) is 25～30%; Described magnesium alloy smelting insulating covering agent is by the weighing of mentioned component difference KCl, LiCl and CaCl ₂Three kinds of chemical substances, be put into after placing mortar to mix 150 ℃ in baking oven down heating 2h make, this insulating covering agent finally is not present in the target alloy.

Compared with prior art, the present invention has following beneficial effect:

(3.5～6.5wt.%) content Mg-Al are that refractory alloy has higher high temperature strength and creep-resistant property to the prepared high Nd of the present invention, can be used as the structured material of motor car engine and transmission system component, also can use other structural parts materials under the higher service temperature of needs.

Description of drawings

The microstructure picture that contains the Nd heat resistance magnesium alloy of Fig. 1: embodiment 2 preparations

Fig. 2: embodiment 1,2 and 3 preparations contain the creep curve of Nd heat resistance magnesium alloy under 150 ℃/70MPa condition.

The invention will be further described below in conjunction with the drawings and the specific embodiments.

Embodiment

Embodiment 1

1) respectively weighing magnesium ingot 910 grams, aluminium ingot 60 grams, Mg-Nd master alloy 180 grams and insulating covering agent 6 grams (wherein KCl is 3.3 grams, and LiCl is 0.9 gram, CaCl ₂Be 1.8 grams) place baking oven to be preheated to 140 ℃;

2) the crucible electrical resistance furnace Heating temperature is set at 780 ℃, when the plumbago crucible temperature rises to 200 ℃, in plumbago crucible, is sprinkled into 6 gram insulating covering agents, and adds magnesium ingot and aluminium ingot;

When 3) treating that Mg-Al alloy melt temperature rises to 750 ℃, add the Mg-Nd master alloy, and under this constant temperature Mg-Al-Nd alloy liquation was stirred 3 minutes, insulation was 30 minutes after stirring was finished;

4) Mg-Al-Nd alloy melt temperature is adjusted to 710 ℃, after leaving standstill 3 minutes, skim alloy liquid surface scum and insulating covering agent, Mg-Al-Nd alloy liquation is cast in the metal pattern, make and contain the Nd heat resistance magnesium alloy, analyzing composition (mass percent) is: Al:5.6%, Nd:3.6%, impurity element Si≤0.02%, Fe≤0.005%, Cu≤0.015%, Ni≤0.002%, surplus is Mg.

The Nd heat resistance magnesium alloy that contains of the present invention is under 175 ℃ of temperature condition, and tensile strength is 157MPa, and elongation is 28.0%; In creep temperature is 150 ℃, and 100 hours total creep amounts under the stress 70MPa condition are 2.40%, as shown in Figure 2.

Embodiment 2

1) respectively weighing magnesium ingot 850 grams, aluminium ingot 65 grams, Mg-Nd master alloy 310 grams and insulating covering agent 25 grams (wherein KCl is 16.25 grams, and LiCl is 2.5 grams, CaCl ₂Be 6.25 grams) place baking oven to be preheated to 160 ℃;

2) crucible electrical resistance furnace is set Heating temperature and be decided to be 780 ℃, when the plumbago crucible temperature rises to 250 ℃, in plumbago crucible, be sprinkled into insulating covering agent 25 grams, and add magnesium ingot and aluminium ingot;

When 3) treating that Mg-Al alloy melt temperature rises to 780 ℃, add the Mg-Nd master alloy, and under this constant temperature Mg-Al-Nd alloy liquation was stirred 5 minutes, insulation was 30 minutes after stirring was finished;

4) Mg-Al-Nd alloy melt temperature is adjusted to 730 ℃, after leaving standstill 5 minutes, skim alloy liquid surface scum and insulating covering agent, Mg-Al-Nd alloy liquation alloy liquid is cast in the metal pattern, make and contain the Nd heat resistance magnesium alloy, analyzing composition (mass percent) is: Al:6.3%, Nd:6.2%, impurity element Si≤0.02%, Fe≤0.005%, Cu≤0.015%, Ni≤0.002%, all the other are Mg.

Alloy of the present invention is under 175 ℃ of temperature condition, and tensile strength is 149MPa, and elongation is 24.0%; In creep temperature is 150 ℃, and 100 hours total creep amounts under the stress 70MPa condition are 1.90%, and as shown in Figure 2, the microstructure picture of alloy as shown in Figure 1.

Embodiment 3

1) respectively weighing magnesium ingot 870 grams, aluminium ingot 63 grams, Mg-Nd master alloy 265 grams and insulating covering agent 12 grams (wherein KCl is 7.2 grams, and LiCl is 1.44 grams, CaCl ₂Be 3.36 grams) place baking oven to be preheated to 150 ℃;

2) crucible electrical resistance furnace is set Heating temperature and be decided to be 760 ℃, when the plumbago crucible temperature rises to 250 ℃, in plumbago crucible, be sprinkled into 12 gram insulating covering agents, and add magnesium ingot and aluminium ingot;

When 3) treating that Mg-Al alloy melt temperature rises to 780 ℃, add the Mg-Nd master alloy, and under this constant temperature Mg-Al-Nd alloy liquation was stirred 2 minutes, insulation was 30 minutes after stirring was finished;

4) Mg-Al-Nd alloy melt temperature is adjusted to 730 ℃, after leaving standstill 4 minutes, skim alloy liquid surface scum and insulating covering agent, Mg-Al-Nd alloy liquid is cast in the metal pattern, make and contain the Nd heat resistance magnesium alloy, analyzing composition (mass percent) is: Al:6.0%, Nd:5.3%, impurity element Si≤0.02%, Fe≤0.005%, Cu≤0.015%, Ni≤0.002%, all the other are Mg.

Alloy of the present invention is under 175 ℃ of temperature condition, and tensile strength is 152MPa, and elongation is 26.0%; In creep temperature is 150 ℃, and 100 hours total creep amounts under the stress 70MPa condition are 2.20%, as shown in Figure 2.

Claims (3)

1, a kind of Nd heat resistance magnesium alloy that contains, it is characterized in that, each component and mass percent thereof are: Al content is 5.5～6.5%, Nd content is 3.5～6.5%, impurity element Si content≤0.02%, Fe content≤0.005%, Cu content≤0.015%, Ni content≤0.002%, Mg are balanced contents.

2, a kind of preparation method who contains the Nd heat resistance magnesium alloy according to claim 1 is characterized in that, may further comprise the steps:

1) with magnesium ingot, aluminium ingot, Mg-Nd master alloy according to target in the alloy weight percent of component get the raw materials ready, and in baking oven, be preheated to 140～160 ℃;

2) the magnesium alloy smelting insulating covering agent is preheated to 140～160 ℃ in baking oven, magnesium alloy smelting insulating covering agent consumption and target alloy total mass ratio are 1/200～1/50;

3) crucible oven is set Heating temperature and is decided to be 780 ℃, when crucible temperature rises to 200～250 ℃, in crucible, be sprinkled into step 2) in the magnesium alloy smelting insulating covering agent of preheating, and add the magnesium ingot and the aluminium ingot of preheating in the step 1), obtain Mg-Al alloy liquation;

When 4) treating that Mg-Al alloy melt temperature rises to 750～780 ℃, the Mg-Nd master alloy that adds preheating in the step 1), obtain Mg-Al-Nd alloy liquation, and under this constant temperature Mg-Al-Nd alloy liquation was stirred 2～5 minutes, insulation was 30 minutes after stirring was finished;

5) Mg-Al-Nd alloy melt temperature is adjusted to 710～730 ℃, leave standstill 3～5 minutes after, skim Mg-Al-Nd alloy molten surface scum silica frost and magnesium alloy smelting insulating covering agent, Mg-Al-Nd alloy liquation be cast in to make in the metal pattern contain the Nd heat resistance magnesium alloy.

3, preparation method according to claim 2 is characterized in that, the component of described magnesium alloy smelting insulating covering agent and mass percent thereof are: KCl is 55～65%, and LiCl is 10～15% and CaCl ₂Be 25～30%.

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