稀土Sm元素对铸态Al-Si-Cu合金组织和力学性能的影响

摘要

通过光学显微镜、扫描电镜及能谱分析，研究了稀土元素钐对铸态Al-Si-Cu 合金组织和力学性能的影响。结果表明：稀土元素钐的添加不仅能有效地细化Al-Si-Cu合金中的α(Al)枝晶和共晶硅相，而且使得富铁相的体积分数下降，其形状从中国汉字状转变为板条状。发现了两种富钐的金属间化合物：AlSiSm相和AlSiCuSm相，块状的 AlSiCuSm 相通常与针状的AlSiSm相连。稀土元素钐的添加使得Al-Si-Cu合金的力学性能得到改善，当钐含量为1.0%时，合金的抗拉强度和伸长率分别为220 MPa和3.1%。%The effects of rare earth samarium (Sm) additions on the microstructure and mechanical properties of as-cast Al-Si-Cu alloy were investigated by optical microscopy and scanning electron microscopy (SEM). The results show that Sm can effectively refine theα(Al) dendrite and the eutectic silicon. In addition, the shape of iron-rich phases changes from the Chinese script-like to slender-like ones and the volume fraction of iron-rich phases is decreased by the addition of Sm. Two kinds of Sm-rich intermetallics are found: AlSiSm and AlSiCuSm. The plate-like AlSiCuSm phase always associates with the needle-like AlSiSm phase. The mechanical properties are improved by the addition of Sm, and the good ultimate tensile strength (220 MPa) and elongation (3.1%) are obtained from the Al-Si-Cu-1.0Sm alloy.