Laser cladding of FeCoNiCrAlCuxSi0·5 high entropy alloys on AZ31 Mg alloy substrates

Abstract

To improve the inherent low hardness and poor corrosion resistance of an AZ31 Mg alloy, FeCoNiCrAlCuxSi0·5 high entropy alloys (HEAs) were clad on Mg alloy substrates using a pre-placed powder bed method and laser re-melting. The results showed that coating dilution by Mg was limited to the interface regions. Similarly, except for a small amount of Cu of the HEA entering into the Mg substrate to a shallow depth, no other HEA elements were found in the re-melted zone of the substrate. The stability of FeCoNiCrAlCuxSi0·5 HEAs with the addition of Mg was evaluated based on the change of the Gibbs free energy. The results showed that the original HEAs without Mg were stable alloys. The microstructure of the FeCoNiCrAlCuSi0·5 and FeCoNiCrAlCu0·5Si0·5 clads consisted of only bcc and fcc simple solid solution phases without intermetallic compounds. With regard to properties, the HEA clads have high hardness and high corrosion resistance.