We have determined the phase transition for the Co-20 and -30 at.% Cu alloys
fabricated by arc melting technique, from the binodal to the two phases þL as
well as the peritectic transitions, using differential thermal analysis (DTA). We
equally studied the effects of aging treatment, ranging from 3 to 35 h, on the alloy
samples using scanning electron microscopy (SEM) and Vickers hardness (HV).
The activation energies of these alloys are equally determined using five
established models. Our results show that for aging time up to 15 h, within the
spinodal region at 773 K, the hardness value for Co-20 and -30 at.% Cu alloys
oscillates reaching a local maximum at the aging time of 8.50.5 h. After 20 h of
heat treatment, the HV for Co-20 at.% Cu alloy diminishes significantly while
that of Co-30 at.% Cu effectively stabilizes at 241 MPa. The activation energies
for the peritectic transformation based on Ozawa model are estimated to be 2465
and 2680 kJ mol1 for Co-20 and -30 at.% Cu, respectively.