Recrystallization Mechanisms Leading to the Formation of Nanoscale Grains in a Ni-20%Cr Alloy Subjected to Intense Plastic Deformation

Abstract

Microstructure evolution during annealing of a Ni-20%Cr alloy subjected to high-pressure torsion (HPT) at ambient temperature was examined. It was shown that recrystallization processes are dependent on the annealing temperature and strain. Discontinuous static recrystallization (DSRX) took place in the alloy strained to <3. Continuous grain growth (GG) occured under subsequent annealing in the material strained to ≥6. It was attributed to the fact that HPT led to the formation of nanoscale grains with an average size of 50 nm. Increasing fraction of these grains with strain led to transition from DSRX to continuous GG under subsequent annealing. The different annealing behavior was attributed to strong strain dependence for the relationship between driving pressures, which were caused by the stored dislocations and the boundary energy.