Plastic Deformation Behaviour and Substructure in CoTi Single Crystals Fatigued at Room Temperature





Cyclic deformation and deformation substructure of CoTi single crystals were examined focusing on operative slip systems and cyclic hardening. Fatigue tests were performed in a tension/compression mode under a fixed amplitude of total strain (Δε=±0.1-±0.3 %) in air at room temperature. CoTi deformed by {110}<001> slips at various strain amplitudes. At Δε=±0.1 % primary (110)[001] slip was dominant and the stress amplitude gradually increased with number of cycles until it reached a saturated value. As secondary slips were more activated with increasing Δε, cyclic hardening was more accelerated and the fatigue life was shortened. Highly piled-up dislocations composed of primary and secondary dislocations formed strong residual stress fields, resulting in crack initiation and propagation. A large number of dipoles and loops which also contributed to cyclic hardening were produced during the to-and-fro motion of <001> screw dislocations.


  • ISIJ international  

    ISIJ international 37(12), 1218-1223, 1997-12-15 

    The Iron and Steel Institute of Japan

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