Al、Ca微合金化对Mg-Gd合金组织及力学性能的影响

Effects of Al and Ca Microalloying on Microstructure and Mechanical Properties of Mg-Gd Alloy

利用光学显微镜、扫描电镜、X射线衍射仪、EDS能谱分析等手段研究了Al、Ca含量对Mg-10Gd-xAl-yCa(x+y=2)合金力学性能的影响。结果表明,用Ca元素替换Mg-10Gd-2Al合金中的Al元素,Mg-10Gd-2Al合金中(Mg,Al)_(3)Gd相形貌由花瓣状变为短棒状、颗粒状,合金抗拉强度随Ca含量的增加呈先增大后减小的趋势;Ca含量为0.5%时,没有发现新相形成,Ca元素全部固溶入基体,产生较强的固溶强化效果,Mg-10Gd-1.5Al-0.5Ca合金的力学性能较好,其抗拉强度、伸长率分别为210.3 MPa、15.6%;当Ca含量超过0.5%时,合金中出现沿晶界分布的粗大共晶相,割裂了基体,降低了合金的力学性能。随着Ca含量增加,合金断裂方式向脆性断裂转变。

The effects of different Al and Ca contents on the mechanical properties of Mg-1oGd-αAl-yCa(x+y=2)alloy were investigated by optical microscopy,scanning electron microscopy,X-ray diffractometry and energy dispersive spectroscopy.The results show that morphology of the(Mg,Al)_(3)Gd phase in Mg-1oGd-2Al alloy is converted from petal shape to short rod shape and granular shape by replacing Al element with Ca element,and the tensile strength of the alloy is increased firstly and then decreased.When the content of Ca is O.5%,absence of new phase can be observed,and Ca elements are all solid dissolved into the matrix,resulting in strong solid solution strengthening effect.The mechanical properties of Mg-10Gd-1.5Al-0.5Ca alloy are desirable,where the tensile strength and elongation reach up to 210.3 MPa and 15.6%,respectively.When the content of Ca exceeds O.5%,the coarse eutectic phase along the grain boundary appears in the alloy,which splits the matrix and reduces the mechanical properties of the alloy.With the increase of Ca element,the fracture mode of the alloy is changed to brittle fracture.