挤压态单/双相镁锂合金的组织与性能

Microstructure and Properties of Extruded Single and Dual Phase Magnesium-Lithium Alloy

对Mg-8.6Li-6.5Zn-1.4Y、Mg-9.6Li-8.9Zn-1.9Y铸态镁锂合金在相同工艺下进行热挤压变形,研究了两种镁锂合金的显微组织、密度和力学性能。结果表明:Mg-8.6Li-6.5Zn-1.4Y铸态合金主要由α-Mg相、β-Li相、Mg_(3)Zn_(6)Y_(1)相组成,为(α+β)双相镁锂合金,Mg-9.6Li-8.9Zn-1.9Y铸态合金主要由β-Li相、Mg_(3)Zn_(6)Y_(1)相组成,为β单相镁锂合金;热挤压变形后,双相镁锂合金中α-Mg相沿挤压方向变形呈条状,单相镁锂合金中形成少量尺寸较小的α-Mg相,两种合金中的Mg_(3)Zn_(6)Y_(1)相均发生破碎并沿挤压方向变形;相比双相镁锂合金,单相镁锂合金的平均晶粒尺寸较小,第二相(Mg_(3)Zn_(6)Y_(1)、Mg_(3)Zn_(3)Y_(2)、LiMgZn相)平均尺寸和体积分数较大,且硬度、屈服强度、抗拉强度更大,分别增加了2.72%,7.53%,3.59%,断后伸长率略有减小。

Mg-8.6Li-6.5Zn-1.4Y and Mg-9.6Li-8.9Zn-1.9Y as-cast magnesium-lithium alloys were deformed under the same hot extrusion process.The microstructures,density and mechanical properties of the two magnesium-lithium alloys were studied.The results show that Mg-8.6Li-6.5Zn-1.4Y as-cast alloy was mainly composed ofα-Mg phase,β-Li phase and Mg_(3)Zn_(6)Y_(1)phase,which was(α+β)dual phase magnesium-lithium alloy.Mg-9.6Li-8.9Zn-1.9Y as-cast alloy was mainly composed ofβ-Li phase and Mg_(3)Zn_(6)Y_(1)phase,which wasβsingle phase magnesium-lithium alloy.After hot extrusion deformation,α-Mg phase of the dual phase magnesium-lithium alloy deformed in strip shape along the extrusion direction,and in the single phase magnesium-lithium alloy a few ofα-Mg phase in small size were formed;Mg_(3)Zn_(6)Y_(1)phase in the two alloys broke and was deformed along the extrusion direction.Compared with those of the dual phase alloy,the average grain size of the single phase magnesium-lithium alloy was smaller,and the average size and volume fraction of the second phase(Mg_(3)Zn_(6)Y_(1),Mg_(3)Zn_(3)Y_(2),LiMgZn phases)were larger,and the hardness,yield strength and tensile strength were higher,which increased by 2.72%,7.53%and 3.59%,respectively,and the elongation percentage after fracture decreased slightly.