摘要
The microstructural evolution and mechanical properties of Al-18 Si-4 Cu-0.5 Mg alloy modified by the addition of La-Ce rare earth elements through OM,SEM,EPMA and tensile tests were investigated.The results of OM and SEM analyses indicated that primary Si particles were significantly refined from coarse block-like and irregular polygonal shapes into fine flaky shapes,while eutectic Si particles were modified from coarse and needle-like into fine and rod-or coral-like shapes with increase of La-Ce addition.The alloy exhibited the minimum primary Si particle size and the best mechanical properties with the addition of 0.3 wt.%La-Ce.The average particle size decreased from 61 to 28 μm,the ultimate tensile strength increased from 222 to 242 MPa and the elongation increased from 3.2% to 6.3%.In addition,modification mechanisms and fracture modes were explored by the means of SEM and EPMA.
通过光学显微镜、扫描电镜、电子探针和拉伸测试研究添加镧铈稀土后Al-18Si-4Cu-0.5Mg合金的组织演变和力学性能。光学显微镜和扫描电镜结果表明,添加镧铈稀土后初晶硅颗粒由粗大块状和不规则多边形状明显细化为细片状,共晶硅由粗长针状细化为短棒状和珊瑚状。添加0.3%镧铈稀土时,合金具有最小初晶硅尺寸和最佳力学性能。此时,初晶硅平均尺寸由61μm细化至28μm,抗拉强度由222 MPa增大到242 MPa,伸长率由3.2%提高至6.3%。此外,还通过扫描电镜和电子探针探究合金的变质机制和断裂模式。
基金
Project(51274245) supported by the National Natural Science Foundation of China
