Suppression of grain boundary steps in chemical mechanical polishing of W-Ni-Fe alloy by a citric acid-based slurry

Abstract

Molds and precision instruments made of tungsten alloy require smooth surfaces. However, it is difficult to achieve smooth surfaces due to grain boundary steps caused by the two-phase microstructure. This letter reports a new method to suppress grain boundary steps by using a citric acid-based slurry in chemical mechanical polishing of W-Ni-Fe alloy. The roles of chemical actions in boundary step generation were investigated. The analytical and experimental results show that proper balance of mechanical and chemical actions can suppress the generation of the boundary steps and lead to good surface finish with the citric acid-based slurry.