Abstract
The strengthening by thermo-mecanical treatment in both Cu-4%Ti and Cu-4%Ti-0.11%Zr alloys was studied by micro-hardness measurements, tensile tests, electron microscopy, and X-ray diffraction.
The following conclusions were obtained.
When the both alloys preaged at 450°C for various times were cold-rolled up to 90% and then annealed finally at 450°C for a short time, their strength was remarkably increased up to 1300 MPa in ultimate tensile strength.
As the annealing temperature was lowered the annealing time required to obtain a maximum hardness by the final annealing was longer.
The increment of hardness by the final annealing depended on the amount of cold rolling, and linear relationships existed between the increments in hardness by cold working and final annealing.
When preageing time was increased, the increment in hardness by the final annealing was decreased to a minimum and then it was increased. The maximum value of the increment in hardness was obtained for the specimens with few supersaturated Ti atoms after preageing.
