Thermal stability of AlCoCrCuFeNi high entropy alloy thin films

High entropy alloys (HEAs), containing five to thirteen metallic elements, with a concentration in the range of 5 to 35 % for each element, exhibit very interesting properties (mechanical, tribological, formability, magnetism...). Their high mixing entropy promotes the formation of simple solid solutions with amorphous or nanocrystallized structure. Bulk pieces of these alloys are known to be stable at relatively high temperature (until 800°C). We study the stability of AlCoCrCuFeNi thin film at temperatures in the range 110 – 810 °C. HEA thin films are deposited by magnetron sputtering of mosaic targets. In-situ X-ray diffraction performed during annealing evidences damages of the film above 510°C depending on the initial structure (or chemical composition) of the as-deposited HEA. Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) analysis carried out before and after annealing on both studied samples, show that partial evaporation of the thin film, crystalline phase transformation and chemical reaction with the substrate may take place during annealing. ha l-0 04 41 65 1, v er si on 1 16 D ec 2 00 9 Author manuscript, published in "Surface and Coatings Technology 204 (2010) 1989-1992" DOI : 10.1016/j.surfcoat.2009.12.006