Mg-Sc-Y三元合金的微观组织和力学性能

稀土元素作为重要的镁合金强化相元素,其多元添加产生的影响并未得到充分研究。在Mg-Sc二元系的基础上将Y作为第三元加入,制备了Mg-5Sc二元合金及Mg-5Sc-0.5Y,Mg-5Sc-1Y,Mg-5Sc-2Y,Mg-5Sc-3Y,Mg-5Sc-3.5Y(质量分数,%)5种三元合金,并通过光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射(XRD)及室温拉伸等试验,研究了Y元素的加入对Mg-Sc二元合金微观组织和力学性能的影响。结果表明:Y元素在合金中的主要存在形式为固溶态,富集于晶界处。随着Y元素含量的提升,合金晶粒度显著减小,屈服强度和硬度大幅提升,Mg-5Sc-3.5Y的屈服强度相比Mg-5Sc提升了约50%。该强度的提升主要是由细晶强化和固溶强化引起的。

Microstructure and Mechanical Properties of Mg-Sc-Y Ternary Alloy

Rare earth is an important strengthening phase element in magnesium alloy. However, the effect of multi-component addition has not been fully studied. In this paper, Y is added as a third element based on the Mg-Sc binary system. Mg-5Sc binary alloy and Mg-5Sc-0.5Y, Mg-5Sc-1Y, Mg-5Sc-2Y, Mg-5Sc-3Y, Mg-5Sc-3.5Y are prepared, and the influence of Y on the microstructure and mechanical properties of the binary alloy is studied by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and room temperature tensile test. The results show that solid solution state is the main form of Y in the alloy, which is rich at the grain boundary. As Y content increases, the grain size decreases significantly. In the mechanical property test, it is found that the addition of Y in the solid solution state can significantly improve mechanical properties and hardness of the Mg-Sc alloy, e.g. the yield strength of the alloy increases from 70 MPa of Mg-5Sc to 109 MPa of Mg-5Sc-3.5Y. This phenomenon is mainly due to the combination of fine grain strengthening and solid solution strengthening.