Al3Ti/A356铝基复合材料的显微组织及拉伸力学性能

Microstructure and high temperature mechanical properties of AlTi/A356 aluminum matrix composite by in-situ reaction

在A356铝合金熔体中加入K2TiF6盐,通过熔体搅拌原位反应法制备了Al3Ti/A356铝基复合材料,研究了Al3Ti含量对铝基复合材料显微组织及室温和高温拉伸力学性能的影响。结果表明,Al3Ti/A356复合材料的铸态组织由α-Al、共晶Si和(Al, Si)3Ti相组成。随着K2TiF6盐添加量的增加,(Al, Si)3Ti相也逐渐增多,其形状由大块状和棒状转变为小块状,同时,基体中的共晶Si细化效果也越显著。在生成不同Al3Ti含量的复合材料中,2wt%Al3Ti/A356复合材料的常温拉伸抗拉强度和屈服强度均为最高,分别为179.7 MPa和74.1 MPa。350℃高温拉伸时,6wt%Al3Ti/A356复合材料的抗拉强度和屈服强度分别比基体提高22.1%和12.6%,分别达到66.3 MPa和57.9 MPa,最高抗拉强度达到或超过了一些现役汽车活塞用的铝硅合金,表明Al3Ti/A356复合材料具有作为新型耐热铝合金应用于汽车发动机耐热部件的潜力。

Al3Ti/A356 composites were prepared through melt stirring in-situ reaction method by adding K2TiF6 salt into the melt of A356 aluminum alloy. The effects of Al3Ti content on microstructure and tensile properties of ascast A356 aluminum alloy at room temperature and high temperature were studied. The results showed that the ascast microstructure of the Al3Ti/A356 composites mainly consists of α-Al, eutectic Si, and(Al, Si)3Ti phases. With the increase of the K2TiF6 salt addition amount, the(Al, Si)3Ti phase gradually increased, and its shape changes from large block and rod-like to small block. Meanwhile, the refining effect of eutectic Si in the matrix was more significant. In composites that produce different Al3Ti, the room temperature tensile strength and yield strength of 2 wt%Al3Ti/A356 composites are the highest, which were 179.7 MPa and 74.1 MPa, respectively. At 350℃, the tensile strength and yield strength of 6 wt%Al3Ti/A356 composite are 22.1% and 12.6% higher than that of A356 aluminum alloy, reaching 66.3 MPa and 57.9 MPa, respectively. The tensile strength of the composite reaches or exceeds that of some Al-Si alloys used for the automotive piston in service. It shows that Al3Ti/A356 composite material has the potential to be used as a new heat resistant aluminum alloy in automobile engine.