70-30黄銅における疲労すべり帯の成長とき裂発生条件の原子間力顕微鏡による定量的評価(<小特集>実験計測技術の新展開)

概要

論文の詳細を見る
Since the surface morphology of materials can be observed with atomic-scale resolution, scanning atomic force microscopy (AFM) in a powerful technique to study mechanisms of fatigue and fracture of solid materials. In the present study, slip-band formation and fatigue crack-initiation processes in 70-30 brass were observed by means of AFM. The slip-band angle relative to the stress-axis at the specimen surface varied from 15 to 90゜, and it appeared most frequently around 60゜. The depth of the intrusion drastically increased with its outgrowth to a crack, and with coalescence of cracks, the width of cracks increased rapidly. The critical value of the intrusion depth for crack initiation was given as a function of the slip-band angle through a geometrical model for the slip-direction and the slip-step, and the critical value was independent of stress amplitude. From presice observations of slip-band tips, slip-bands had steep slope when they were blocked by grain boundaries, and the slip-bands descended by gradual slopes to plain surfaces when they terminated within grains.
2001-03-25