Microstructure, dislocation density and microhardness of 1 %C-doped CoCrFeNi complex concentrated alloys during isochronal annealing

Abstract

In this study, a microstructure of moderately deformed 1 %C-doped CoCrFeNi complex concentrated alloys (CCA) was investigated in a correlation with microstructure evolution at different annealing temperature for 1 h. After 60 % thickness reduction of cold rolling, the dislocation density accumulated as large as 19 × 1015 m−2. The interstitial carbon atom was a key factor inducing large dislocation storage and caused large stored strain energy of 368 J/mol. The recrystallization was completed at 1173 K for 1 h and the average recrystallized grain size was as fine as 3.7 µm. During the annealing between 973 and 1173 K, the carbides were increasingly precipitated with an increase in annealing temperature. The carbon addition delayed the recrystallization process due to solute drag effect and carbide precipitations. The conventional fabrication method produced the fine recrystallized microstructure attributed to the large dislocation density of the deformed microstructure and carbide precipitation.