Stress relaxation experiments were performed at temperatures ranging from room temperature to 1073K in order to study changes in the motion and structure of dislocations introduced into Co-Ni-based alloy. A resultant zero rate of stress relaxation at room temperature could be attributed to the immobilization of introduced dislocations which originated from an elastic interaction between dislocation cores and solute atoms. At high temperatures, where dynamic strain aging occurred, the zero rate of stress relaxation in the initial stage could be attributed to a dislocation-locking effect which was caused by Suzuki segregation. Stress relaxation in the dynamic strain aging temperature range occurred merely via the movement of leading partial dislocations; resulting in wide dislocation dissociation. Upon exceeding the dynamic strain aging temperature range, the dislocation locking effect, caused by Suzuki segregation, faded away and the 2 partial dislocations glided simultaneously by viscous motion, resulting in the lack of any observable wide dislocation dissociation. Phase diagram calculations and microstructural observations revealed that the present alloy (SPRON 510) was a supersaturated solid solution and that the occurrence of Suzuki segregation was strongly associated with the degree of supersaturation in the solid solution.

Suzuki Segregation and Dislocation Locking in Supersaturated Co-Ni-Based Alloy. A.Chiba, M.S.Kim: Materials Transactions, 2001, 42[10], 2112-6