Y含量对Mg-4Sm-0.6Zn-0.5Zr合金组织及性能的影响

Effects of Y Content on Microstructure and Mechanical Properties of Mg-4Sm-0.6Zn-0.5Zr Alloy

研究了Y元素对Mg-4Sm-0.6Zn-0.5Zr合金组织及力学性能的影响。结果发现,Mg-4Sm-0.6Zn-0.5Zr合金主要由α-Mg基体、Mg_(24)Y_(5)相、(Mg,Zn);(Y,Sm)相、LPSO结构的Mg_(24)YZn相组成。随着Y含量增加,晶粒逐渐细化,晶界共晶相数量增多,在晶界位置存在共晶次生LPSO相Mg_(24)YZn。LPSO相与α-Mg基体共格,提高了镁合金的强度和硬度。随着Y含量增加,Mg-4Sm-0.6Zn-0.5Zr合金的力学性能不断提高,Y含量达到6.89%时,铸态Mg-4Sm-7Y-0.6Zn-0.5Zr合金的硬度(HV)、屈服强度、抗拉强度以及伸长率分别为95.6、118 MPa、193 MPa、10.5%。Mg-4Sm-0.6Zn-0.5Zr合金的断口和裂纹深度随着Y含量的增加逐渐变浅,台阶数目减少,由准解理脆性断裂转变为解理脆性断裂。

The influences of Y element on the microstructure and mechanical properties of Mg-4 Sm-0.6 Zn-0.5 Zr alloy were investigated.The Mg-4 Sm-xY-0.6 Zn-0.5 Zr alloy is mainly composed ofα-Mg matrix,Mg_(24)Y_(5)phase,(Mg,Zn);(Y,Sm)phase,and Mg_(24)YZn phase with LPSO structure.With the increase of Y content,the grains are gradually refined and the amount of eutectic phases at the grain boundary is increased.There exists a eutectic secondary LPSO phase Mg_(24)YZn at the grain boundary.The LPSO phase Mg_(24)YZn is coherent with theα-Mg matrix,which improves the strength and hardness of the magnesium alloy.With the increase of Y content,the mechanical properties of Mg-4 Sm-0.6 Zn-0.5 Zr alloy is improved continously.With the Y content of 6.89%,the hardness,yield strength,tensile strength and elongation of the as-cast Mg-4 Sm-7 Y-0.6 Zn-0.5 Zr alloy reach up to 95.6 HV,118 MPa,193 MPa,10.5%,respectively.The structure of LPSO has an effect on the fracture behavior of magnesium alloy.The fracture mechanism of Mg-4 Sm-7 Y-0.6 Zn-0.5 Zr alloy is characterized by cleavage brittle fracture,and the fracture and crack depth gradually become shallower.