Age hardening of the Al0.3CoCrFeNiC0.1 high entropy alloy

In this study, an Al0.3CoCrFeNiC0.1 high entropy alloy was synthesized by induction melting in air. The as-cast alloy was heat treated for 5-72h at 600-1000 degrees C to investigate the effects of age treatments on the hardness and microstructure. The microstructure of the as-cast alloy consisted of a FCC solid solution matrix and an eutectic k(1) carbide. This k(1) carbide decomposed to a k(2) carbide after being aged at 800-1000 degrees C. The optimal age hardening occurred at 700 degrees C, and the hardening effect decreased with further increase in temperature. The precipitation of fine k(2) carbides in the matrix during 700-1000 degrees C aging is the main age hardening mechanism. In addition, the precipitation of a Ni-Al rich phase at 800 degrees C and 900 degrees C provides a secondary hardening effect. (C) 2008 Elsevier B.V. All rights reserved.