Exploring the transfer of plasticity across Laves phase interfaces in a dual phase magnesium alloy

TL;DR

This study investigates how plasticity transfers across interfaces in a dual-phase magnesium alloy, combining experiments and atomistic simulations to understand slip transfer mechanisms and interfacial effects at room temperature.

Contribution

It provides new experimental and simulation evidence of slip transfer mechanisms in Mg alloys, highlighting the role of interface orientation and sliding in plasticity transfer.

Findings

Slip transfer occurs from Mg matrix to Laves phase at room temperature.

Two mechanisms for slip transfer depend on crystallographic orientation.

Interfacial sliding can inhibit plasticity transfer.

Abstract

The mechanical behaviour of Mg-Al alloys can be largely improved by the formation of an intermetallic Laves phase skeleton, in particular the creep strength. Recent nanomechanical studies revealed plasticity by dislocation glide in the (Mg,Al)$_2$Ca Laves phase, even at room temperature. As strengthening skeleton, this phase remains, however, brittle at low temperature. In this work, we present experimental evidence of slip transfer from the Mg matrix to the (Mg,Al)$_2$Ca skeleton at room temperature and explore associated mechanisms by means of atomistic simulations. We identify two possible mechanisms for transferring Mg basal slip into Laves phases depending on the crystallographic orientation: a direct and an indirect slip transfer triggered by full and partial dislocations, respectively. Our experimental and numerical observations also highlight the importance of interfacial sliding that can prevent the transfer of the plasticity from one phase to the other.