Effect of stacking fault energy on irradiation damage in reduced activation high entropy alloys

In order to investigate the effect of stacking fault energy on microstructural evolution in reduced activation high entropy alloys, electron and/or Au + ion irradiation was performed to the Co-free FCC-type FeCr 0.8 Ni x Mn y ( x, y = 1, 1.3, 1.5) alloys. TEM observation of the 5%-deformed FeCr 0.8 Ni x Mn y alloys revealed the increase in the stacking fault energy with increasing both Ni and Mn concentration. In addition, FeCr 0.8 Ni 1.5 Mn 1.5 had the highest stacking fault energy, which was much higher value than that of 316SS. Furthermore, the yield strength and the elongation of deformed FeCr 0.8 Ni x Mn y also showed the Ni and Mn concentration dependence. The electron irradiation at 400 degrees C resulted in the formation of black dots, self-interstitial atom faulted loops, but no observable voids in all the FeCr 0.8 Ni x Mn y alloys. The comparison of microstructural evolution revealed less faulted loop formation and growth in FeCr 0.8 Ni 1.3 Mn 1.3 and FeCr 0.8 Ni 1.5 Mn 1.5 alloys. From these results, it is suggested that FeCrNiMn-based high entropy alloys would be developed as high irradiation resistant materials by controlling the stacking fault energy with optimized element concentration.