锶对连续定向凝固Al-Si共晶合金组织与性能的影响

Effects of Sr on the Structure and Behaviours of Continuously Directional-Solicified A1-Si Eutectic Alloy

本文采用新型的连续定向凝固装置,考察了锶对 Al-12.7%Si 共晶合金连续定向凝固组织及性能的影响。研究表明,在凝固速度为0.02～2.0mm/s 范围内,随凝固速度的增加,Al-12.7%Si合金连续定向凝固组织中共晶 Si 经历了片/纤维转变,且随凝固速度的增加,Si 纤维不断细化,合金的抗拉强度及延伸率不断提高;锶的加入使片/纤维转变的临界速度变小,Si 纤维更加细小,抗拉强度和延伸率明显提高。

In this paper,the effects of Sr on the structure and behaviours of con- tinuously directional-solidified Al-12.7% Si eutectic alloy has been investigated by a new type of continuously directional solidification apparatus.The study showed that the flake/fibre transition of eutectic silicon takes place with the increase of freezing rate in a range from 0.02 mm/s to 2.0 mm/s,and mean- while the silicon fibres are becoming finer,and the tensile strength and per- centage elongation increasing.The addition of Sr to the alloy makes the cri- tical freezing rate Rc smaller,the eutectic silicon fibre finer,and the tensile strength and percentage elongation larger.