Microstructural Change by Friction Stir Processing in Zr-Al-Cu-Ni Bulk Metallic Glass

Abstract

Microstructural change by friction stir processing (FSP) is examined in Zr-Al-Cu-Ni bulk metallic glass. The microstructure in the friction zone (FZ) exhibits an amorphous “band-like” structure, and a small number of nanoscale crystalline particles are observed along the “band-like” structure. The change in hardness with the microstructural change is examined and it is revealed that the hardness in FZ greatly increases although the volume fraction of crystalline phase is very limited. The increasing hardness is possibly explained from the combined effect of low temperature annealing during FSP and nano-size of crystalline particles.