摘要
The present study is an effort towards enhancing the age hardening response of FCC based non-equiatomic CoCrFeNi HEA alloys with systematic variations of Ti and Al. Upon aging a sharp increase in the hardness was observed with increasing the Ti to Al ratio. This was attributed to the enhanced precipitate number density and finer precipitate size. The results also suggested a significant variation in the precipitate morphology with changing the Ti/Al ratio. The needle-shaped, spherical and cuboidal shaped precipitates were formed in Al 0.5 Co 1.5 CrFeNi 1.5 (Al 05 ), Al 0.2 Co 1.5 CrFeNi 1.5 Ti 0.3 (Al 02 Ti 03 ) and Co 1.5 CrFeNi 1.5 Ti 0.5 (Ti 05 ) HEAs, respectively. A quantitative assessment of precipitate characteristics viz. precipitates size, area fraction, interparticle spacing and its correlation with strengthening have been established. It was found that Orowan model is appropriate for predicting the yield strength of Al 02 Ti 03 and Ti 05 alloys.