Sm对Mg-10Gd-0.5Zr合金组织及力学性能的影响

Effect of Sm on microstructures and mechanical properties of Mg-10Gd-0.5Zr alloy

摘要:

采用熔炼铸造法制备了添加1-5wt%Sm的Mg-10Gd-0.5Zr合金,通过拉伸性能测试、扫描电镜、X射线衍射分析研究了Sm对合金显微组织和力学性能的影响。结果表明：Sm的加入形成了Mg₄₁Sm₅相,并促进了Mg₅Gd相析出。固溶时效处理后,晶界处粗大共晶组织溶解,析出相弥散分布,3%Sm的合金晶粒较细小,5%Sm的合金中出现短棒状Mg₅Gd相。在相同实验温度下,随着Sm含量的增加,合金的强度先升高后降低,3%Sm的合金抗拉强度最大。对于同一种合金,随着拉伸温度的升高抗拉强度先升高后降低,0~1% Sm的合金抗拉强度峰值出现在200℃,加入3~ 5%Sm的合金抗拉强度峰值出现在250℃。抗拉强度具有明显的反常温度效应,而且Sm的加入强化了这种反常温度效应并使强度峰值出现的温度升高。

Abstract:

Mg-10Gd-0.5Zr alloys with 1-5wt% Sm addition were prepared by melting and casting method. The effect of Sm on microstructures and mechanical properties were investigated by tensile tests, SEM and XRD. The results show that the Mg₄₁Sm₅ phase is found because of Sm addition, Sm promotes the precipitation of Mg₅Gd. After solution-aging treatment, the coarsening eutectic structures at grain boundary were dissolved and the precipitation dispersed homogeneous. The finer grain size is observed when content of Sm come to 3wt%. Some of Mg₅Gd phase become short rod-like when Sm addition is 5wt%. Under the same experimental temperature, the strength of tested alloys increases at fist and then decrease, and peak strength present when content of Sm is 3wt%. For the same alloy, with increasing of test temperature, the strength increase at fist and then decrease too. When Sm content is 0~1wt%, the temperature of tensile strength peak is 200℃ and the temperature is 250℃ when Sm content is 3~5wt%. There are abnormal temperature effects in tensile tests, the effect is reinforced and the temperature of tensile strength peak rise with the Sm addition.