INFLUENCE OF ALLOYING ELEMENTS (NI, CO, A G, BI, P) ON ANNIHILATION OF OROWAN LOOPS AROUND ALPHA-FE PARTICLES IN CU MATRIX

The effects of additions of alloying elements (Ni, Co, Ag, Bi, P) on t he recovery of work hardening have been studied in Cu single crystals with nearly spherical alpha-Fe particles, Adding the solute elements d oes not change the softening mechanism; that is, Orowan loops around t he particles climb and disappear by pipe diffusion through their own c ores. For the alloys with Ni, Co, Ag and Bi, the loop climb rate decre ases with increasing concentration of each element and eventually beco mes a certain value. At the stage, the activation energies Q for pipe diffusion are approximately 70% of the activation energies for bulk di ffusion of the elements in Cu. The addition of the elements also incre ases the frequency factor D-0 for pipe diffusion. The Q and D-0 values remain unchanged by the P addition. It is shown that these observatio ns are evidently brought about by the significant presence of each ele ment in the proximity of the dislocation core. The softening after wor k hardening in the Ag-added Cu alloy single crystals containing rod-sh aped alpha-Fe particles has also been examined with respect to two kin ds of geometrical relationships between the Orowan loops and the flat habit plane of the particles. In the first case the Orowan loops touch the habit plane during climbing, while in the second case they do not . Although the Ag addition results in the increase of Q and D-0 in bot h cases, the former has smaller values of Q and D-0 than the latter. T his is because the amount of Ag segregation on the habit plane is lowe r than that on the matrix-particle interface.