Study of microstructural defects in steel using positron annihilation lifetime technique

摘要

Positron annihilation lifetime technique has been applied to study the microstructural changes in steel after heat treatment (tempering process). Positron lifetime spectra for the tempered samples in sandwich configuration with the positron source were accumulated at room temperature using a conventional fast-fast coincidence timing system. The measured lifetime spectra have been analyzed in terms of various components using the PATFIT program. A correlation between the macroscopic mechanical properties and the positron annihilation parameters has been established. Meanwhile, with the aid of image analysis method, the ASTM grain size in treated samples was determined. The two state trapping model has been applied for interpretation of experimental results.