Investigation of mechanical properties of NixCoyCrz thin film through combinatorial analysis

NiCoCr, a medium entropy alloy with high strength and excellent ductility at low temperatures, has increased interest for extreme environment applications, but its relatively poor room-temperature yield strength has driven studies to enhance its mechanical properties through non-equiatomic compositions. Ni x Co y Cr z was prepared using co-sputtering from Ni, Co, and Cr targets that allowed for the synthesis of a thin film with a wide compositional range in which each element varied between 17 and 57 at. %. The coating consisted of single-phase face-centered cubic and multiphase regions containing hexagonal close-packed and sigma phases. Nanoindentation analysis was performed as an effective high-throughput method for determining the effect of the composition on the mechanical properties of Ni x Co y Cr z alloy, and elastic modulus and hardness mapping was acquired. Notably, Ni 20 Co 40 Cr 40 exhibited the highest hardness of 7.45 GPa within the single-phase region, primarily attributed to enhanced non-linear Co–Cr interactions that impede dislocation motion. This work successfully proposed, via a high-throughput method, the composition with the highest strength and captured the trend in strength relative to the bulk values.