Al-3Y-2B中间合金对Al-20Si铸态组织和力学性能的影响

Effect of Al-3Y-2B master alloy on the microstructure and mechanical properties of Al-20Si casting

研究了Al-3Y-2B中间合金对过共晶Al-20Si二元合金铸态组织及性能的影响规律,基于冷却曲线分析(CCA)方法,测得了Al-20Si二元合金中加入Al-3Y-2B中间合金前后的冷却曲线。实验结果表明:Al-20Si合金熔体加入1.0%的Al-3Y-2B中间合金后,初生硅的生成温度降低约13℃;铸态组织的初生硅平均尺寸由110μm减小到33μm,初生硅形貌由粗大的多边形结构转变为尺寸细小的板状结构;共晶硅形貌由细长针状转变为短针状和短棒状;铸态合金的伸长率(EL)由1.62%提升到1.98%,极限抗拉强度(UTS)由120 MPa提升到162 MPa。Al-3Y-2B的添加量为0.5%时,组织中的初生硅和共晶硅被很好的细化;Al-3Y-2B的添加量提高到1.0%时,Al基体中开始出现脆性相,影响合金的机械性能。

The influence of Al-3Y-2B master alloy on the as-cast microstructure and properties of hypereutectic Al-20Si binary alloy were studied.Based on the cooling curve analysis(CCA)method,the cooling curve before and after the addition of Al-3Y-2B master alloy in Al-20Si binary alloy was measured.The experimental results showed that the primary phase generation temperature decreased by about 13℃when 1.0%Al-3Y-2B master alloy was added to Al-20Si alloy melt.The average size of primary silicon decreased from 110μm to 33μm,and the morphology of primary silicon changed from coarse polygonal structure to fine plate structure.The morphology of eutectic silicon changed from the slender needles to short needles and rods.The elongation(EL)of the as-cast alloy increased from 1.62%to 1.98%,and the ultimate tensile strength(UTS)increased from 120 MPa to 162 MPa.When the amount of Al-3Y-2B was 0.5%,the primary silicon and eutectic silicon were refined well.When the addition of Al-3Y-2B increased to 1.0%,the brittle phase began to appear in Al matrix,which affected the mechanical properties of the alloy.