Si、Cu、Ti对亚共晶铝硅合金组织与性能的影响

Effects of Si,Cu and Ti on the Microstructure and Properties of Hypoeutectic Al-Si Alloys

使用正交试验的方法研究了Si、Cu、Ti三种合金元素对铸造亚共晶铝硅合金组织及性能的影响。结果表明,铸态合金中主要由α(Al)、共晶Si、θ-Al_(2)Cu、Q-Al_(5)Cu_(2)Mg_(8)Si_(6)和Π-Al_(8)Mg_3FeSi_(6)相组成,热处理后θ-Al_(2)Cu相更均匀的析出,而Π相转变为β-Al_(5)FeSi(Cu)相。经过元素调控和T6热处理后的铸造铝硅合金通过力学性能测试发现,当Si含量为9%、Cu含量为1.5%、Ti含量为0.1%时,T6(固溶520℃保温5 h+时效180℃保温4 h)处理的铝合金强塑性匹配达到最佳。合金的室温抗拉强度和伸长率分别为422 MPa和6.2%,250℃保温1 h的高温抗拉强度和伸长率分别为215 MPa和9.6%,为缸盖材料的应用和发展提供了一定的理论指导。

The effects of Si,Cu and Ti on the microstructure and properties of cast hypoeutectic Al-Si alloys were studied by orthogonal test.The results showed that the as-cast alloy was mainly composed ofα(Al),eutectic Si,θ-Al_(2)Cu,Q-Al_(5)Cu_(2)Mg_(8)Si_(6) andΠ-Al_(8)Mg_3FeSi_(6) phases.After heat treatment,theθ-Al_(2)Cu phase precipitated more well-distributed,and theΠphase transformed intoβ-Al_(5)FeSi(Cu)phase.The mechanical properties test of cast Al-Si alloy after element regulation and T6 heat treatment showed that when Si content was 9%,Cu content was 1.5%,Ti content was 0.1%,the strength and plastic matching of aluminum alloy treated with T6(solution holding at 520℃for 5 h and aging at 180℃for 4 h)was the best.The tensile strength and elongation of the alloy were 422 MPa and 6.2%,respectively at room temperature,and the high temperature tensile strength and elongation of 250℃for 1 h were 215 MPa and 9.6%,which provides a certain theoretical guidance for the application and development of cylinder head materials.