Ca对Mg-5Al-1Bi合金显微组织和力学性能的影响

使用X射线衍射仪、金相显微镜、扫描电镜、能谱仪及力学性能测试等试验手段,研究了Ca含量对铸态Mg-5Al-1Bi镁合金显微组织和力学性能的影响。结果表明,铸态Mg-5Al-1Bi镁合金由α-Mg基体和β-Mg17Al12相组成,加入Ca后,合金晶粒细化,β-Mg17Al12相的数量减少,由连续变得较为分散。当Ca含量达到3%时,合金中生成新的第二相Al2Ca。高熔点相Al2Ca在高温条件下能钉扎晶界,阻碍晶界滑移,有利于提高合金的高温蠕变性能。合金硬度和屈服强度随着Ca含量的增加而提高,而抗拉强度和伸长率下降。

Effect of Ca on Microstructures and Mechanical Properties of Mg-5Al-1Bi Alloys

Effects of Ca content on microstructure and mechanical properties of Mg-5Al-1Bi alloy were investigated by XRD(X-ray diffraction),OM(optical microscope),SEM(scanning electron microscope),EDS(energy dispersive spectrometer) and mechanical property testing.The results show that the as-cast microstructure of the Mg-5Al-1Bi alloy is composed of matrix α-Mg and β-Mg17Al12 phases.With the addition of Ca,grains are refined,and the amount of phase Mg17Al12 is decreased with the morphologies transformed from continuous shape into more dispersed ones.The new secondary phase Al2Ca is generated with the Ca content increasing to 3%.Al2Ca phase with high melting point can pin the grain boundaries to restraint its slippage,which is beneficial to improve the high temperature creep resistance of the alloys.The hardness,yield strength are increased with the addition of Ca content,however,the tensile strength and elongation are decreased.