The effects of secondary elemental Mo or Ti addition in Al_(0.3)CoCrFeNi high-entropy alloy on age hardening at 700 °C

摘要

Three FCC structured high-entropy alloys of Al_(0.3)CoCrFeNi, Al_(0.3)CoCrFeNiMo_(0.1), and Al_(0.3)CoCrFeNiTi_(0.1) were synthesized in order to investigate the effects of secondary elemental Mo or Ti addition in Al_(0.3)CoCrFeNi alloy on age hardening at 700°C All of the three alloys exhibited an apparent age hard-ening, especially when secondary elements were added. The hardness of the Al_(0.3)CoCrFeNi alloy was increased by 65% after aging, whereas the other two alloys displayed an increase of over 80%. The Al_(0.3)CoCrFeNi and Al_(0.3)CoCrFeNiTi_(0.1) alloys were hardened by massive (Ni,Al)-rich and (Ni,Co,Ti)-rich B2 ordered precipitates, respectively. The large age hardening of the Al_(0.3)CoCrFeNiMo_(0.1) alloy is attributed to the precipitation of both fine (Ni,Al)-rich phase and heavy blocky (Cr,Mo)(Co,Fe,Ni) a phase.