Tribology of TiNbCr MPEA: Insights into tribolayer formation and resulting wear resistance

This study investigates the tribological behavior of the equiatomic TiNbCr multi-principal element alloy (MPEA), focusing on the role of phase constitution and microstructural heterogeneity in wear performance. The alloy exhibits a microstructure composed of a Nb- and Ti-rich BCC matrix and a Cr-rich C15 Laves phase, resulting in high hardness (~ 466 HV 0.5 ) and a relatively low elastic modulus (115 ± 4 GPA). Tribological tests reveal wear behavior dependence on the counter-body material Al 2 O 3 or Si 3 N 4 . Against Si 3 N 4 , the alloy shows superior wear resistance despite higher friction ( µ ≈ 0.7), which may be associated with the formation of a Si-containing tribolayer and the high hardness of the TiNbCr substrate. In contrast, sliding against Al 2 O 3 promotes unstable tribolayer formation, leading to material removal due to adhesive interaction and material transfer. These findings demonstrate that dry sliding wear resistance in TiNbCr MPEAs is governed by intrinsic mechanical properties and by tribochemical reactions.