ABSTRACT Refractory multi‐principal element alloys (RMPEAs) are attractive for elevated‐temperature tribology, yet many exhibit pronounced wear‐resistance degradation from ambient to medium temperatures (approximately 25°C–500°C). Conventional approaches typically rely on temperature‐specific, in situ tribo‐oxide formation, which limits the improvement to narrow operating windows. Here we demonstrate an oxygen‐induced amorphization strategy in NbMoWTaTi that produces a mechanically robust composite oxide tribo‐layer and suppresses medium‐temperature wear degradation. Oxygen incorporation into the chemically short‐range ordered NbMoWTaTi matrix promotes uniformly dispersed Ti─O clusters, leading to local lattice instability and spatially uniform amorphization. During sliding at 500°C–650°C, this process generates a composite oxide tribo‐layer comprising an amorphous matrix containing ultrafine WO 3 nanocrystals (∼5 nm), which exhibits high hardness and stiffness and supports ultra‐low wear (on the order of 10 −7 mm 3 ·N −1 ·m −1 ). In addition, pre‐fabrication of a comparable composite oxide layer reduces the wear rate by one to two orders of magnitude from 25°C to 400°C relative to the untreated alloy. These results establish oxygen‐induced amorphization as a design strategy for forming stable, high‐strength oxide tribo‐layers and achieving enhanced wear resistance across a broad service‐temperature range.
Pei et al. (Sat,) studied this question.