冷却速率对粗晶铸造TiAl合金显微组织的影响

Effects of Cooling Rate on Microstructure of TiAl Alloy with Coarse Grain

采用磁悬浮感应熔炼铸造方法制备了晶粒粗大的Ti-46Al-2Nb-2Cr合金。通过显微组织观察,研究了在高温预处理过程中,不同淬火介质下的冷却速率对铸态合金显微组织的影响。结果表明,冷却速率明显影响了粗晶铸造Ti-46Al-2Nb-2Cr合金的显微组织。快速冷却有利于后续热处理晶粒的细化,提高细化效果,加快细化的进程;冷却速率较慢则会降低细化效果,降低细化的速率。

Ti-46Al-2Nb-2Cr alloy with coarse grain was prepared by induction skull melting with a non-consumable electrode. The effects of cooling rate on as-cast microstructure of alloy during pre-treated process at high temperature were observed by OM (optical microscope) and SEM (scanning electron microscope)in case of different quenching conditions . The results reveal that the cooling rate has obvious effect on microstructure of the alloy with coarse grain. High cooling rate can improve the refinement of grain in the alloy after heat treatment,strengthening refining effect and promoting the process of refinement,while low cooling rate can decrease the refining effects and restrain the refining velocity.