EFFECT OF THERMOMECHANICAL TREATMENT ON THE PHASE-TRANSFORMATION IN CU-44NI-5CR ALLOY

Cu-44Ni-5Cr alloy has been subjected to thermomechanical treatment whi ch consisted of plastic deformation of as-quenched material by 50, 65 and 80% reduction in thickness followed by ageing in the interval of 5 00 to 650 degrees C for various durations of time. Progress in age-har dening was studied by means of hardness measurement and X-ray diffract ion studies. The wavelength of composition modulation and strain ampli tude were measured. It was found that age-hardening was a result of in teraction between spinodal decomposition and recovery processes. Prior deformation was found to enhance the kinetics of both spinodal decomp osition and coarsening. It was concluded that this resulted from incre ased vacancy concentration and increased coherency strain in the cold- worked material.