The interaction of precipitation and deformation in a binary Mg-Ca alloy at elevated temperatures

The effect of pre-deformation on precipitation hardening response as well as the work-hardening behavior of a binary Mg-Ca alloy are investigated. Our results show that application of 5% pre-deformation increases the precipitation hardening response of the material and decreases the annealing time by 50%. The dislocations introduced during the pre-deformation process act as predominant nucleation sites and result in a higher number of precipitates of smaller size. During the thermomechanical treatments, the work hardening behavior is altered by the state of the precipitates, namely, under-aged, peak-aged and over-aged. After the elastic-plastic transition, under-aged and peak-aged materials show a continuously decreasing work-hardening rate, while the over-aged material has an initial constant work-hardening rate. The absolute values of the work hardening rate are far less sensitive to the precipitation stage compared to aluminum alloys; a fact that explains the low work hardening capacity of magnesium compared to aluminum.