深冷及时效处理对快冷Al-0.3Sc-0.3Zr合金组织及析出行为的影响

Effect of cryogenic and aging treatment on microstructure and precipitation behavior of rapidly cooled Al-0.3Sc-0.3Zr alloy

采用高真空感应熔炼与铜模喷铸相结合的方法制备了非平衡凝固Al-0.3Sc-0.3Zr合金,研究了深冷和时效处理对快冷合金微观组织、显微硬度及析出行为的影响。结果表明:快冷合金中的Sc和Zr元素基本固溶到α-Al基体中,仅有微量初生相形成;深冷处理后,应力碎断效应导致合金的晶粒发生显著细化,局部出现非常细小的再结晶组织;时效处理能有效促进快冷及快冷+深冷合金中析出相的析出。经300℃时效70 min后,Al-0.3Sc-0.3Zr快冷合金的硬度由原始的32.31 HV0.2增至74.57 HV0.2。深冷处理可以加快Al_(3)(Sc, Zr)相的析出,300℃时效峰值时间缩短为50 min,合金的显微硬度高达78.09 HV0.2,相比原始快冷合金提高了142%。

A non-equilibrium solidified Al-0.3Sc-0.3Zr alloy was prepared by high vacuum induction melting and copper mold spraying.Effect of cryogenic and aging treatment on microstructure,microhardness and precipitation behavior of the rapidly cooled alloy were studied.The results show that the Sc and Zr elements in the rapidly cooled alloy are basically dissolved into theα-Al matrix,and only a small amount of primary phase is formed.After cryogenic treatment,the stress fragmentation effect leads to significant refinement of the alloy’s grains and the appearance of ultra fine recrystallized structure in local region.Aging treatment can effectively promote the precipitation of precipitates in the rapidly cooled and rapidly cooled+cryogenic treated alloy.After aging at 300℃for 70 min,the hardness of the rapidly cooled Al-0.3Sc-0.3Zr alloy increases from the original 32.31 HV0.2 to 74.57 HV0.2.Cryogenic treatment can accelerate the precipitation of Al_(3)(Sc,Zr)phases,shorten the peak aging time at 300℃to 50 min,and achieve a microhardness of 78.09 HV0.2,which is 142%higher than the original rapidly cooled alloy.