AlNiCrFeMn Equiatomic High Entropy Alloy: A Further Insight in Its Microstructural Evolution, Mechanical and Surface Degradation Response

The microstructure and properties of an equiatomic AlCrFeMnNi high entropy alloy (HEA) in the as-cast condition are presented. The microstructure consists of two phases (NiAl-rich B2 and FeCr-rich A2) featuring various eutectic morphologies, ranging from regular to anomalous development. Solidification phenomena (undercooling and recalescense) are used in order to assess the various morphological features along with theories of anomalous eutectic growth. Sliding wear testing shows an oxidation-delamination mode of material removal along with some partial abrasive mode character. Modulus of elasticity and yield point are significantly high and elongation presents at a satisfying level, whereas fracture surface examination reveals the characteristics of a brittle fracture mode. High temperature oxidation tests show multiple oxidation phenomena of different kinetics, formed oxide phases and material deterioration phenomena. Graphic