Surface hardening of CrCoFeNi high-entropy alloys via Al laser alloying

Abstract

Undeformed face-centred cubic (FCC) high-entropy alloys (HEAs) always possess excellent plasticity but low hardness. In this work, Al alloying on the surface of a CrCoFeNi FCC HEA is realized by laser alloying technique. An Al1.5CoCrFeNi body-centred cubic (BCC) HEA is in-situ generated on the surface of the FCC HEA. The well-bonding BCC HEA layer possesses a hardness as high as 536 HV. The hard surface results in a much lower wear rate of the Al-alloyed specimen than the pristine specimen. This study provides a simple strategy to harden the FCC HEAs by in-situ formation of BCC HEA through laser alloying.