CN104818415A

CN104818415A - High-strength heat-resistant magnesium alloy

Info

Publication number: CN104818415A
Application number: CN201510291169.1A
Authority: CN
Inventors: 张清; 陈君; 李全安; 李武会; 朱利敏; 张兴渊
Original assignee: Henan University of Science and Technology
Current assignee: Henan University of Science and Technology
Priority date: 2015-06-01
Filing date: 2015-06-01
Publication date: 2015-08-05

Abstract

The invention discloses a high-strength heat-resistant magnesium alloy and belongs to the technical field of magnesium alloy materials. The high-strength heat-resistant magnesium alloy comprises the following components in percentage by mass: 5.5-6.2% of Y, 0.5-0.7% of Ce, 0.4-0.6% of Zr, 0.2-0.5% of Sb and the balance of Mg and inevitable impurities. The magnesium alloy is prepared by taking pure Mg and Sb as well as intermediate alloys of Mg-25%Y, Mg-25%Ce and Mg-25%Zr as raw materials, smelting and casting to obtain magnesium alloy ingots at first, then performing solid-solution treatment on the magnesium alloy ingots sequentially for 8 hours at 525 DEG C, and performing aging treatment for 16 hours at 225 DEG C. The magnesium alloy disclosed by the invention has relatively high room-temperature and high-temperature strength, and has relatively good strength stability at 200-300 DEG C.

Description

A kind of high-strength heat-resisting magnesium alloy

Technical field

The invention belongs to technical field of magnesium alloy material, be specifically related to a kind of high-strength heat-resisting magnesium alloy.

Background technology

As the lightest structural metallic materials, the application of magnesium alloy on automobile is increasing.Adopt magnesium alloy to alleviate vehicle weight, reduce energy consumption, reduce exhaust emissions simultaneously, alleviate environmental pollution, for automotive industry important in inhibiting.But, the intensity of magnesium alloy and resistance toheat are not good, particularly under high temperature, intensity declines to a great extent, and serious hinders its application in aerospace, automotive industry, therefore improves the important subject that the intensity of magnesium alloy and stable high-temperature strength are field of magnesium alloy.

By suitable alloying, can improve the resistance toheat of magnesium alloy, wherein, rare earth (RE) improves the most effective alloying element of magnesium alloy resistance toheat.Rare earth element can crystal grain thinning, the room temperature strength of magnesium alloy is improved by refined crystalline strengthening, the high-melting-point rare earth compound of disperse can also be formed, still can pinning intracrystalline dislocation and Grain Boundary Sliding when high temperature, improved the hot strength of magnesium alloy by dispersion-strengthened, Mg-RE system (as WE system) alloy can be worked at relatively high temperatures.But, along with the rising of temperature, the intensity of Mg-RE system alloy (as commercial heat resistance magnesium alloy WE43) declines to a great extent, cause hot strength unstable, this can have a strong impact on the safe reliability that Magnesium Alloys Components at high temperature works, and makes it can not meet aerospace, the requirement of automotive industry to component intensity at 200 DEG C-300 DEG C completely.

Summary of the invention

The object of this invention is to provide a kind of high-strength heat-resisting magnesium alloy, improve the room temperature of magnesium alloy and hot strength and the strength stability at 200 DEG C-300 DEG C thereof.

In order to realize above object, the technical solution adopted in the present invention is: a kind of high-strength heat-resisting magnesium alloy, its mass percent consists of: 5.5 ~ 6.2%Y, 0.5 ~ 0.7%Ce, 0.4 ~ 0.6%Zr, 0.2 ~ 0.5%Sb, and surplus is Mg and inevitable impurity.In described impurity, Si, Fe, Cu and Ni total amount is less than 0.2%.

Described magnesium alloy is with pure Mg and Sb, and master alloy Mg-25%Y, Mg-25%Ce and Mg-25%Zr are raw material, first obtain magnesium alloy ingot through melting, casting, then, by magnesium alloy ingot successively through 525 DEG C of solution treatment 8 hours, and 225 DEG C of ageing treatment obtained after 16 hours; Prepared magnesium alloy inside generates Mg ₁₂ce and Mg ₃sb ₂high-melting-point strengthening phase.

The present invention adopts heavy rare earths Y to be the first component, and the maximum solid solution degree of Y in Mg is 12wt%, and for ensureing strengthening effect and controlling cost of alloy, the add-on of Y elects 5.5 ~ 6.2wt% as; Adopt light rare earths Ce and heavy rare earths Y to combinationally use, the solid solubility of Y in Mg can be reduced, reduce the consumption of Y, thus reduce content of rare earth total in alloy, and then reduce cost of alloy.The maximum solid solution degree of Ce in Mg is 0.74wt%, and in order to ensure strengthening effect and reduce total content of rare earth as far as possible, the add-on of Ce elects 0.5 ~ 0.7wt% as, and Ce and Mg can generate Mg ₁₂ce phase, this Compound Phase fusing point is higher, at high temperature still can keep higher hardness, pinning dislocation and crystal boundary, thus makes alloy at high temperature still have higher intensity; Adding a small amount of Zr can crystal grain thinning, improves room temperature strength; Add a small amount of Sb and generate high-melting-point strengthening phase Mg ₃sb ₂, improve hot strength; Utilize the comprehensive action of rare earth element y, Ce and element Zr, Sb, improve room temperature and the hot strength of alloy.

Beneficial effect: the room temperature tensile intensity of commercial heat resistance magnesium alloy WE43 is 260MPa, and 200 DEG C of tensile strength are 240MPa, 250 DEG C is 220MPa, and reduce to 160MPa for 300 DEG C, when 300 DEG C, tensile strength can not meet service requirements, and maximum operation (service) temperature is 250 DEG C.With WE43 alloy phase ratio, heat resistance magnesium alloy of the present invention, its room temperature and high temperature tensile strength higher, 300 DEG C time, tensile strength still can reach more than 200MPa, and use temperature can reach 300 DEG C, and the strength stability 200 DEG C-300 DEG C time is good, and is better than WE43.The present invention meets the applied at elevated temperature requirement of magnesium alloy to a certain extent, has broad application prospects in aerospace, automotive industry etc.In addition, heat resistance magnesium alloy middle-weight rare earths consumption of the present invention is lower, and wherein, the mass percent sum of rare earth element y and Ce, lower than 7%, far below the content of existing high-strength heat-resistant magnesium alloy middle-weight rare earths, significantly reduces cost of alloy.

Embodiment

Purity raw materials used in the specific embodiment of the invention is the Mg of 99.8%, the Sb of 99.5%, Mg-25%Y, Mg-25%Ce and Mg-25%Zr of 99.8%.

embodiment 1

The present embodiment high-strength heat-resisting magnesium alloy is made up of the component of following mass percent: 6.2%Y, 0.5%Ce, 0.4%Zr, 0.2%Sb, and surplus is Mg and inevitable impurity, and wherein impurity element S i, Fe, Cu and Ni total amount is less than 0.2%.Rare earth total content is 6.7%.

Prepare each raw material by above-mentioned alloying constituent, the preparation technology of described magnesium alloy is: adopt corundum crucible, induction furnace melting.At CO ₂+ SF ₆under mixed gas protected; first by pure Mg and Sb fusing; then master alloy Mg-25%Y, Mg-25%Ce and Mg-25%Zr is added; carry out melting; then, liquid magnesium alloy is warming up to 750 DEG C and pours into steel die, obtains magnesium alloy ingot; heat-treat subsequently: 525 DEG C of solution treatment 8 hours, 225 DEG C of ageing treatment 16 hours.Obtain product, gained magnesium alloy inside generates Mg ₁₂ce and Mg ₃sb ₂high-melting-point strengthening phase.

The method of the present embodiment high-strength heat-resisting magnesium alloy tensile strength test: the test block after solid solution, ageing treatment, is processed into standard tensile specimen according to standard GB/T 6397-86 " metal stretching experimental sample ".Shimadzu AG-I 250kN electronic tensile test machine stretches, and rate of extension is 1mm/min.During drawing by high temperature, 5 minutes are incubated and stretch again.

The heat resistance magnesium alloy of the present embodiment gained, its room temperature tensile intensity is 266MPa, and 200 DEG C of tensile strength are 246MPa, and 250 DEG C is 228MPa, and 300 DEG C still up to 214MPa; With WE43 alloy phase ratio, content of rare earth is lower slightly, and intensity is higher, and use temperature can reach 300 DEG C, and strength stability when 200 DEG C-300 DEG C is better than WE43.

embodiment 2

The present embodiment high-strength heat-resisting magnesium alloy is made up of the component of following mass percent: 5.8%Y, 0.6%Ce, 0.5%Zr, 0.3%Sb, and surplus is Mg and inevitable impurity, and wherein impurity element S i, Fe, Cu and Ni total amount is less than 0.2%.Rare earth total content is 6.4%.

The melting of the present embodiment high-strength heat-resisting magnesium alloy, casting, thermal treatment process, and tensile strength test method is with embodiment 1.

The heat resistance magnesium alloy of the present embodiment gained, its room temperature tensile intensity is 262MPa, and 200 DEG C of tensile strength are 244MPa, and 250 DEG C is 224MPa, and 300 DEG C still up to 210MPa; With WE43 alloy phase ratio, content of rare earth is lower slightly, and intensity is higher, and use temperature can reach 300 DEG C, and strength stability when 200 DEG C-300 DEG C is better than WE43.

embodiment 3

The present embodiment high-strength heat-resisting magnesium alloy is made up of the component of following mass percent: 5.5%Y, 0.7%Ce, 0.6%Zr, 0.5%Sb, and surplus is Mg and inevitable impurity, and wherein impurity element S i, Fe, Cu and Ni total amount is less than 0.2%.Rare earth total content is 6.2%.

The heat resistance magnesium alloy of the present embodiment gained, its room temperature tensile intensity is 260MPa, and 200 DEG C of tensile strength are 240MPa, and 250 DEG C is 222MPa, and 300 DEG C still up to 206MPa; With WE43 alloy phase ratio, content of rare earth is lower slightly, and intensity is higher, and use temperature can reach 300 DEG C, and strength stability when 200 DEG C-300 DEG C is better than WE43.

Claims

1. a high-strength heat-resisting magnesium alloy, is characterized in that: its mass percent consists of: 5.5 ~ 6.2%Y, 0.5 ~ 0.7%Ce, 0.4 ~ 0.6%Zr, 0.2 ~ 0.5%Sb, and surplus is Mg and inevitable impurity.

2. a kind of high-strength heat-resisting magnesium alloy as claimed in claim 1, it is characterized in that: described magnesium alloy is with pure Mg and Sb, and master alloy Mg-25%Y, Mg-25%Ce and Mg-25%Zr are raw material, first obtain magnesium alloy ingot through melting, casting, then, by magnesium alloy ingot successively through 525 DEG C of solution treatment 8 hours, and 225 DEG C of ageing treatment obtained after 16 hours; Prepared magnesium alloy inside generates Mg ₁₂ce and Mg ₃sb ₂high-melting-point strengthening phase.