Abstract

AlCoCrCuFeNi high entropy alloy (HEA) coatings were formed on AZ91-Mg substrates using a two-step laser cladding technique that was adopted to solve the HEA melting problem due to the large difference in their melting temperatures. First, a layer composed of partially melted HEA powders in an AZ91 Mg matrix was produced, i.e. a composite layer, followed by laser cladding on the composite layer surface. The results showed that the top layer of the coating had a bcc solid solution structure and no intermetallic compound was detected. The dilution behaviour and the reactions between the HEA powder and the matrix were studied. In the composite layer, the Cu from the HEA powder was the main element that entered into the substrate melt, however, no serious dilution occurred. The solidification reactions at the HEA powder surface were determined using the corresponding Mg-Al-Cu phase diagrams that were constructed based on the CALPHAD approach.