Al-3B对A356.2再生铝合金熔体净化的影响研究

Research on the Effect of Al-3B on Melt Purification of Recycled A356.2 Aluminum Alloy

摘要: 文章研究了A356.2再生铝合金在770℃浇铸温度、90 min保温时间条件下，向A356.2再生铝合金熔体中添加不同质量分数(1 wt%, 2 wt%, 3 wt%, 4 wt%)的Al3B中间合金对熔体净化效果的影响。采用金相显微镜、X射线衍射仪、扫描电镜、拉伸试验机、布氏硬度计及直读光谱仪开展测试表征。结果表明，Al-3B可通过硼化反应与熔体中Fe生成稳定的Fe₂B相并沉降除铁，同时显著细化晶粒、改善脆性富铁相形貌。随着Al-3B添加量的增加，合金抗拉强度与伸长率先升后降，2 wt%添加量时综合力学性能最优，抗拉强度达161.1 MPa、伸长率为3.71%，除铁率在2 wt%时达到峰值7.71%。

Abstract: This study investigated the effect of different mass fractions (1 wt%, 2 wt%, 3 wt%, and 4 wt%) of Al-3B master alloy on the melt purification of recycled A356.2 aluminum alloy, under the conditions of a casting temperature of 770˚C and a holding time of 90 min. Metallographic microscopy, X-ray diffractometry (XRD), scanning electron microscopy (SEM), tensile testing, Brinell hardness testing, and direct-reading spectrometry were employed for comprehensive characterization. The results show that Al-3B reacts with Fe in the melt via boronization to form stable Fe₂B phase, which is then removed by sedimentation. Meanwhile, the addition of Al-3B significantly refines the grain structure and modifies the morphology of brittle iron-rich phases. With increasing Al-3B addition, the tensile strength and elongation of the alloy first increase and then decrease. The optimal comprehensive mechanical properties are achieved at 2 wt% Al-3B addition, with a tensile strength of 161.1 MPa and an elongation of 3.71%. Additionally, the iron removal efficiency reaches a peak of 7.71% at the same 2 wt% addition level.