金属间化合物大晶粒超塑性

Superplasticity of Large-Grained Intermetallics

在所研究的Fe3Al,Fe3Si,FeAl,Ni3Al,NiAl和TiAl等金属间化合物中均发现大晶粒超塑性.金相分析表明,超塑性变形过程中晶粒明显细化;透射电子显微学(TEM)和位向成像显微学(OIM)分析表明,超塑性变形过程中大量亚晶形成亚晶网络,且随变形量增大,网络内小角度及大角度亚晶界密度不断增高,即发生连续动态回复与再结晶.高温塑性变形是通过位错的滑移和攀移进行的,而亚晶界的迁移、滑动和转动起到协调变形的作用,保持了材料在宏观上的超塑性.

Superplastic behavior was found in Fe3Al, Fe3Si, FeAl, Ni3Al, NiAl and TiAl alloys with large grain sizes (30-600 μm). The large-grained intermetallic alloys exhibit all deformation characteristics of fine-grained superplastic alloys without the usual pre-requisites of a fine grain size and grain boundary sliding. Metallographic examinations show that the average grain size of large-grained intermetallics decreases during superplastic deformation and a much finer grain size can be obtained after the superplastic deformation. Transmission electron microscopy (TEM) and orientation image microscopy (OIM) observations show that there are great numbers of subgrain boundaries which form a network and among which the proportion of low and high angle boundaries increases with the increase of the strain. The observed superplastic phenomenon was explained by continuously dynamic recovery and recrystallization (CDRR).