Microstructure, mechanical properties and corrosion resistance of CuZrY/Al, Ti, Hf series high-entropy alloys

Abstract

A series of high-entropy alloys (HEAs) CuYZrTiHf (Z1), CuYZrAlHf (Z2) and CuYZrAlTi (Z3) were prepared by arc melting. All these HEAs mainly consist of hexagonal close-packed (hcp) dendrites and CuY-type body-centered cubic (bcc) interdendrite phases. The result affirmed that principal elements with hcp structure and suitable atomic size are beneficial to the formation of hcp dendrites. Specially, small content of amorphous phase appears in Z3 HEA, which is related to the increased melt viscosity and principal elements used for preparing bulk metallic glasses. The compressive strength and plastic strain of Z1 are 1340MPa and 13.2%, indicating a plastic fracture. Z2 and Z3 HEAs have higher Vickers hardness and compressive strength but the plasticity is severely depressed. The electrochemical corrosion measurements in the seawater solution were carried on. Z1 and Z2 HEAs possess better corrosion resistance and Z3 has a higher pitting resistance. According to the observation of corrosion morphologies, the interdendritic region containing CuY-type phase is feasible to preferential corrosion.