High-Temperature Sliding Wear Behavior of Zr-Based Bulk Amorphous Alloys

Bulk metallic glasses (BMGs) and their coatings are very attractive for tribological applications because of their high hardness. However, the frictional heat at the contact surfaces causes several effects such as oxidation, viscous flow, and nanocrystallization in the amorphous alloys. High-temperature wear testing offers an excellent way to characterize these effects and transitions in wear mechanisms. In this article, dry sliding wear behavior of the Zr-based BMG (Zr64.13Cu15.75Ni10.12Al10) is investigated in the temperature range of 293 K (room temperature) to 673 K. The wear surfaces showed indications of surface oxidation, viscous flow, formation of a protective layer, and abrasive wear, depending on the wear testing temperature. The Zr-based BMG exhibited the lowest wear rate of 9.7 × 10−4 mm3 m−1 associated with the formation of the protective surface layer at 473 K. With wear testing near glass transition temperature (574–673 K), the profuse crystallization of the surface seemed to change the wear mechanism to abrasive wear, resulting in the breaking of the protective layer and a high wear rate.