The dynamic deformation and shear localization in Mg-10 wt % Ca alloy

The deformation behavior and mechanical properties of Mg-10 wt % Ca alloy have been investigated under both quasi-static and dynamic loading conditions. The dynamic tests are conducted using the classical Split Hopkinson Pressure Bar (SHPB) at high strain rates of ∼10³ s⁻¹. It consists of primary (Mg) phase and (Mg) + Mg₂Ca eutectic phases. Mechanical properties show that both the flow stress and strain rate sensitivity are improved, compared with pure Mg and some classical magnesium alloys. The deformation mechanisms differ under quasi-static and dynamic compression conditions. Under quasi-static strain rates, the primary deformation mechanism is dislocation motion. Simultaneously, dissociation of basal <a> dislocation into two Shockley partial dislocations causes SFs and the {0001} <10-10> basal slip system is activated. However, at higher strain rates, the deformation mechanism is predominantly assisted by mechanical twins (MTs). Especially, the {10–11} MTs are activated in the Mg₂Ca phases. Basal SFs contiguous to {10–11} twins are also observed. Additionally, adiabatic shear band (ASB) forms under dynamic loading conditions, suppressing the instant brittle failure.