Carbon defect induced evolution of structural and mechanical properties in substoichiometric (HfMoNbZr)Cx films

Substoichiometric (HfMoNbZr)Cx films with varied carbon content were synthesized using non-reactive magnetron sputtering. Findings reveal that the (HfMoNbZr)Cx film predominantly exhibits a single-phase FCC structure, which transforms to a dual-phase structure consisting of FCC and Hex. phases at higher carbon content. This behavior arises from the segregation of group VB (Nb) and VIB (Mo) elements from the FCC lattice. The film hardness (H) and elastic modulus (E) increases with rising carbon content accompanied by a decrease of coefficient of friction (COF). However, the wear rate is not decreased despite the increased H and reduced COF of the as-deposited films. This phenomenon is explained by examining the differences in the wear mechanisms between (HfMoNbZr)Cx films with single- and dual- phase structures.