铸造AlSi7MgLa铝合金的金相组织和力学性能研究∗

摘要

Addition of rare earth element La in cast aluminum alloy plays an important role.The rare earth element La is added to the aluminum alloy melt through the Al-9.38%La rare aluminum alloy,and the AlSi7MgLa cast aluminum alloy is obtained.The microstructure and mechanical property of AlSi7MgLa alloy is studied by metallographic microscope and e-lectronic universal material testing machine.Results show that the morphology of eutectic silicon is changed by rare earth La.When the addition of rare earth La is 0.31%,eutectic silicon forms a fine particle.The strength of the alloy is high to 116 MPa.When the amount of La is 0.87%,there is La phase separation more than eutectic silicon,and the mechanical property of alloy is decreased.The strength of the alloy is decreased further to 52 MPa.%在铸造铝合金中，添加稀土元素镧可以起到明显的效果。通过 Al-9.38%La 稀土铝中间合金向铝合金熔体加入稀土元素镧，制得了铸造 AlSi7MgLa 铝合金。用金相显微镜和电子万能材料试验机研究了铸造AlSi7MgLa铝合金的金相组织和力学性能，结果表明，稀土元素镧能改变共晶硅的形貌，当稀土元素镧的加入量为0.31%时，共晶硅形成细小的颗粒状，合金的强度较高，为116 MPa。当稀土元素镧加入量为0.87%时，有比共晶硅粗大的稀土元素镧相析出，降低了合金的力学性能，合金的强度进一步下降到52 MP a。