微量元素Cr对Al-13Si-3Cu-2Ni-1Mg-0.5Fe合金微观组织和力学性能的影响

Effect of Trace Element Cr on Microstructure and Mechanical Properties of Al-13Si-3Cu-2Ni-1Mg-0.5Fe Alloy

采用惰性气体保护的电阻熔炼技术制备了不同Cr含量的Al-13Si-3Cu-2Ni-1Mg-0.5Fe合金。采用OM、SEM、EDS、XRD、布氏硬度仪和电子万能试验机分析了铸态和热处理态下不同Cr含量合金的微观组织、相组成、硬度分布、室温和高温力学性能。结果表明,添加Cr元素之后,合金中的长针状或片状的β-Al FeSi相逐渐转变成短棒状或汉字状的α-Al FeSi相。随着Cr含量增加,短棒状α-Al FeSi相数量明显增多。添加不同Cr的铸态合金布氏硬度和抗拉强度均较未加Cr的合金轻微减小。经热处理之后,合金硬度和抗拉强度较铸态明显提升;添加Cr元素之后,合金的高温抗拉强度显著提升,Cr含量为0.45%时,合金高温抗拉强度高达129 MPa,较未加Cr的合金(95 MPa)提升了35.8%。

The Al-13 Si-3 Cu-2 Ni-1 Mg-0.5 Fe alloys with different Cr contents were prepared by inert gas shielded resistance melting technology. The microstructure, phase composition, Brinell hardness, room temperature and high temperature tensile strength of the as-cast and heat-treated the alloys with different Cr contents were analyzed by using OM,SEM, EDS, XRD, Brinell hardness tester, and electronic universal testing machine. The results show that the long needle-like or plate-like β-Al FeSi phase in the alloy gradually transforms into short needle-like or Chinese-like α-Al FeSi phase after adding Cr element. The number of short rod-like α-Al FeSi phase significantly increases as the content of Cr element increases.The Brinell hardness and tensile strength of the as-cast alloys with different Cr contents slightly decrease compared with those of the alloy without Cr element. After heat treatment, the Brinell hardness and tensile strength of the alloys are significantly enhanced;compared with those of the as-cast alloy without Cr element, the tensile strength at high temperature increases significantly;When the Cr content is 0.45%, the high temperature tensile strength of the alloy is 129 MPa, which is 35.8%higher than that of the alloy(95 MPa) without Cr element.