Defect microstructure in high temperature Ni+ implanted FeCrCoNi-a positron beam study.

Positron beam measurements carried out on high temperature Ni+ implanted FeCrCoNi show no void formation but only presence of monovacancies. With thermal treatment, evidence for the formation of nano sized σ-CoCr are obtained from positron based ratio curve analysis in the temperature range 973–1123 K. Corroborative evidence for the presence of these precipitates are obtained from EBSD and GIXRD measurements. Further annealing beyond 1150 K leads to coarsening of these precipitates and they no longer trap the positrons. • First time study on the defect microstructure and its evolution in high temperature Ni+ implanted FeCrCoNi using the variable low energy positron beam. • Defect sensitive S-parameter reveals presence of monovacancies for the high temperature implanted condition. No presence of voids observed. • Positron beam based ratio curve analysis show formation of nano sized CoCr precipitates after annealing beyond 1023 K. [ABSTRACT FROM AUTHOR]