Effect of Prior Cold Working before Aging on the Precipitation Behavior in a Cu-3.5 wt% Ti Alloy

Cu-Ti alloys were strengthened by Cu4Ti intermetallic compound precipitation in a Cu matrix during aging. The Cu-3.5 wt% Ti(Cu-4.6 at% Ti) alloys without deformation and with uniform and non-uniform deformation were aged at 450 degrees C for various times after solution treatment at 885 degrees C. The uniformly and non-uniformly deformed alloys show slip and shear band formation in the matrix, respectively. The deformation bands, slip or shear bands, were still maintained even after 12 hours of aging at 450 degrees C. The conductivity of all the specimens continuously increased, but the hardness reached the peak value and then decreased during aging. The hardness and conductivity of the specimen with shear bands had a higher value than the specimens without deformation and with slip bands. Additionally, the time to reach peak hardness of the specimen with shear bands was shortened to 30 minutes compared to 720 and 1440 minutes for specimens with slip bands and without deformation bands, respectively. The highest combination value of conductivity and hardness, 16.8% IACS and 302 Hv, was obtained in the specimen with shear bands after aging for 360 minutes.