Influences of Fe and B on the Columnar Structure of Ti-46Al Alloys

摘要:

对利用非自耗电弧熔炼设备得到的Ti-46Al, Ti-46Al-0.3B, Ti-46Al-0.5B, Ti-46Al-2Fe, Ti-46Al-2Fe-0.3B和Ti-46Al-2Fe-0.5B合金的凝固组织进行了研究。结果表明，铸态TiAl基合金的宏观组织为典型的柱状晶组织，而且平均柱状晶直径随着Fe和B元素的加入显著减小。其中，Ti-46Al-2Fe-0.5B合金的柱状晶直径最小。B元素可以显著地细化TiAl基合金的柱状晶组织和枝晶组织，这主要是由于B元素的添加可以显著增加固液界面前沿的成分过冷度从而细化TiAl基合金的凝固组织。而且，Fe元素的添加还可以显著地提高B元素对TiAl基合金的柱状晶组织的细化效果

Abstract:

The microstructures of Ti-46Al, Ti-46Al-0.3B, Ti-46Al-0.5B, Ti-46Al-2Fe, Ti-46Al-2Fe-0.3B, and Ti-46Al-2Fe-0.5B alloys solidified on water-cooled copper crucible were investigated. It is found that the as-cast alloys possess a typical columnar structure, and the mean diameters of the columnar grains decrease significantly as the addition of Fe or B. The mean columnar diameter in Ti-46Al-2Fe-0.5B is found to be the smallest among these alloys. B addition can increase the constitutional supercooling in front of the solid-liquid interface, which refines the columnar structure and the dendritic structure. Moreover, Fe addition can enhance the refining effect of boron on the columnar structure of TiAl-based alloys