Fe-28Al-5Cr与Fe-28Al-5Cr-0.5Nb-0.1C合金的超塑性变形能力及特征

THE SUPERPLASTICITY OF Fe-28Al-5Cr AND Fe-28Al-5Cr-0.5Nb-0.1C ALLOYS

研究了 Ｆｅ－２８Ａｌ－５Ｃｒ（原子分数）与 Ｆｅ－２８Ａｌ－５Ｃｒ－０．５Ｎｂ－０．１Ｃ合金的高温变形行为，结果表明，在 ８５０ ℃左右，应变速率为 ８．３×１０－４ ｓ－１时，呈现一定的超塑性变形能力，延伸率分别达到 １４５％和 ２５４％；应变速率敏感指数 ｍ分别为 ０．４与 ０．３５；激活能分别为： ２４３ ｋＪ／ｍｏｌ与 ２１８ ｋＪ／ｍｏｌ．在变形过程中，位错堆积形成小角度晶界，并逐渐转变成大角度晶界，使粗大的原始晶粒细化．

High temperature deformation behaviors of two Fe-28Al-5Cr based intermetallic alloys have been investigated. These alloys exhibit superplastic behavior within the temperature range from 750 ℃ to 950℃ at the strain rate of 8.3× 10-4 s-1. Maximum tensile elongations of 145% and 254% are obtained respectively. The deformation activation energies are measured to be about 243 kJ/mol for Fe-28Al-5Cr alloy and 218 kJ/mol for Fe-28Al-5Cr-0.5Nb-0.1C alloy. During high temperature tensile, the dislocations pile up to form sub-grain boundary or small angular grain boundary which refines the original coarse grains.