Coherency evaluation of α-Mg/C15-Al₂Ca interface for a Mg-Al-Ca alloy

Abstract

The C15-Al₂Ca precipitates were observed using high-resolution transmission electron microscopy (HRTEM) to identify the coherency of the α-Mg/C15-Al₂Ca interface for the Mg-5Al-1.5Ca alloy aged at the temperature range from 548 to 598 K. The α/C15 coherent interface turned to the semi-coherent one by the introduction of misfit dislocations on the planar surface of the C15 precipitates for the alloy aged at 598 K for 1 h, whereas the coherency was maintained for the alloy aged at 548 K for 10 h. The curve showing the loss of interface coherency was drawn in the TTP diagram for the Mg-5Al-1.5Ca alloy, which is indicated that the α/C15 interface coherency has remained within 3.6×10⁷ s (10000 h) at 500 K.