时效处理和挤压后预变形工艺对Mg-Gd合金组织和力学性能的影响

将挤压态Mg-4Gd合金沿挤压方向进行10%预拉伸处理,然后研究了时效处理对预变形后合金组织和力学性能的影响。结果表明:预拉伸处理产生加工硬化的同时促进了变形镁合金中灰暗过渡相及明亮平衡相的形核,时效过程加速了过渡相的形成及其向平衡相的转化。随着时效温度升高,明亮平衡相的平均尺寸增加。预拉伸试样经时效处理可提高力学性能,当时效工艺为210℃×24 h时,合金综合力学性能最佳,其硬度、屈服强度、抗拉强度和伸长率分别为66.65 HV0.1、137.4 MPa、245.4 MPa和22.1%;时效温度升高使得合金的峰值硬度降低,但达到硬度峰值所需时间缩短且强度和伸长率均保持在较高水平。

Effects of aging treatment and pre-stretching process after extrusion on microstructure and mechanical properties of Mg-Gd alloy

The extruded Mg-4 Gd alloy was pre-stretched by 10% along the extrusion direction, and then the effect of aging treatment on microstructure and mechanical properties of the alloy was studied. The results show that the pre-stretching treatment not only produces work hardening, but also promotes the nucleation of gray and dark transition phase and bright equilibrium phase in the magnesium alloy, the aging treatment accelerates the formation of transition phase and its transformation to equilibrium phase. With the increase of aging temperature, the average size of bright equilibrium phase increases. The mechanical properties of the pre-stretched alloy can be improved by aging treatment. The comprehensive mechanical properties of the alloy after aging at 210 ℃ for 24 h are the best, its hardness, yield strength, tensile strength and elongation are 66.65 HV0.1, 137.4 MPa, 245.4 MPa and 22.1%, respectively. The peak hardness of the alloy decreases with the increase of aging temperature, but the time needed to reach the peak hardness is shortened and the strength and elongation are kept at a high level.