Processing maps for hot working of a P/M iron aluminide alloy

The hot working behavior of a Fe-24 wt.% Al iron aluminide alloy processed by the powder metallurgy route has been studied in the temperature range 75 0-1150 degreesC and strain rate range 0.001-100 s(-1) by establishing proce ssing maps at different strains in the range 0.1-0.5. The features in the p rocessing maps have changed with strain suggesting that the mechanisms of h ot deformation are evolving with strain. Early in the deformation (strain o f 0.1), the map exhibited a single domain with a peak efficiency of power d issipation of about 44% occurring at about 1100 degreesC and a strain rate of about 0.03 s(-2). This domain represents dynamic recrystallization (DRX) of the initial material possibly causing a substantial grain refinement. W ith increasing strain, a bifurcation has occurred giving rise to two domain s: (1) at strain rates lower than about 0.1 s(-1) and temperatures above 10 00 degreesC, superplastic deformation has occurred, and (2) at strain rates higher than about 10 s(-1) and temperatures above 1125 degreesC, DRX has o ccurred. The material exhibited flow localization at lower temperatures and higher strain rates. On the basis of the processing maps, the optimum proc essing routes available for hot working of this material are outlined. (C) 2000 Elsevier Science Ltd. All rights reserved.