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研究了Sr对Al-20%Si合金组织和力学性能的影响。结果表明,随着Sr量的增加,初晶硅先由角块状或大板片状变为小块状再到多角的大块状,板片上出现大量蜂窝点,块状初晶硅角边发生钝化;共晶硅先由长针叶状变为细短纤维状或枝状再变为粗短枝状或蠕虫状;α枝晶不断柱状化,数量不断增多。另外,随Sr量的增加,合金伸长率逐渐增大,但有起伏,抗拉强度先急剧增加后变化不大,硬度呈抛物线变化。Sr量在0.04%~0.06%间,组织形貌最为理想,综合力学性能最优,强度和硬度增加2倍多,塑性增加近4倍。
The effect of Sr on the microstructure and mechanical properties of Al-20% Si alloy was investigated. The results show that with the increase of the amount of Sr, the primary silicon begins to transform from small block or large plate to small block to multi-corner block. A large number of honeycomb dots appear on the plate, Occurs passivation; eutectic silicon first long coniferous to short fibers or dendritic then into a short short or wormlike; α dendrite columnar continuously, the increasing number. In addition, with the increase of the amount of Sr, the elongation of the alloy gradually increases, but there is fluctuation, the tensile strength first increased sharply changed little, the hardness showed a parabolic change. The content of Sr is between 0.04% and 0.06%, the microstructure is the best, the comprehensive mechanical properties are the best, the strength and hardness increase more than twice and the plasticity nearly increase four times.