时效工艺对WE43镁合金组织与力学性能的影响

研究了WE43稀土镁合金在不同热处理工艺下显微组织、力学性能的变化规律,从而得出最佳的热处理工艺。研究结果表明WE43稀土镁合金铸态组织为等轴状晶粒,比较均匀,平均晶粒尺寸为40 μm;铸造冷却凝固的过程中,在晶界处形成了离异共晶组织;经520 ℃×8 h固溶处理后的组织,共晶相的数量和形态发生了明显的变化,枝晶偏析基本消除,晶界上仍有少量未溶的第二相。230 ℃×8 h时效后稀土第二相的数量增加,并且在晶粒内部析出了点状弥散的稀土相;经过250 ℃×16 h的时效后,合金的硬度达到了峰值,随着时效时间的继续延长,合金的硬度下降。固溶处理后WE43稀土镁合金的抗拉强度为162.59 MPa左右,断后伸长率约为5.0%;而经过250 ℃时效处理后,其抗拉强度明显增加,断后伸长率在4%左右。

Effect of aging process on microstructure and mechanical properties of WE43 magnesium alloy

Evolution of microstructure and mechanical properties of WE43 rare earth magnesium alloy under different heat treatment processes was studied in order to optimize the heat treatment process. The results show that the as-cast microstructure of the WE43 rare earth magnesium alloy is relatively uniform, with equiaxed grains of average grain size of 40 μm. During the process of solidification, the divorced eutectic forms along the grain boundaries. After solution treatment at 520 ℃ for 8 h, for the structure of the divorced eutectic, the number and morphology change significantly, the dendrite segregation is basically eliminated, and there are still a small amount of undissolved second phases on the grain boundary. After aging at 230 ℃ for 8 h, the amount of rare earth second phase increases, and dot-like dispersed rare earth phases are precipitated inside the grains. After aging at 250 ℃ for 16 h, the hardness of the alloy reaches its peak, the hardness of the alloy then decreases gradually as the ageing time extending. After solution treatment, the tensile strength of the WE43 rare earth magnesium alloy is about 162.59 MPa, and the elongation after fracture is about 5.0%, while after aging at 250 ℃, its tensile strength is significantly increased, and the elongation after fracture is about 4%.