Investigation of near surface defects in metal samples produced by mechanical cutting/polishing using positron annihilation spectroscopy

Jiang, L.*; Oshima, Nagayasu*; O'Rourke, B. E.*; Suzuki, Ryoichi*; Harada, Yoshihisa*; Suzuki, Takayuki*; Takatsu, Shuhei*; Hirade, Tetsuya  ; Takai, Kenichi*

Positron annihilation spectroscopy (PAS) is a sensitive method for detection of defects such as vacancies, vacancy clusters and nano-voids. The positron probe microanalyzer (PPMA) in AIST can investigate defect distribution of materials using a scanning positron microbeam. For the application of the PPMA for analysis of such materials it is important to consider the defects introduced during the sample preparation. we are investigating two kinds of sample preparation process, electrical discharge machining (EDM) and colloidal silica polishing after EDM. We are studying the depth dependence of the density of the defects induced by these processes in various metals, including SUS316L, using PAS.