Terrace-like morphology of the boundary created through basal-prismatic transformation in magnesium

Abstract

Boundaries created through basal-prismatic transformation in submicron-sized single crystal magnesium have been investigated systematically using in situ transmission electron microscopy. We found that these boundaries not only deviated significantly from the twin plane associated with f1 0 1 2g twin, but also possessed a non-planar morphology. After the sample was thinned to be less than 90 nm, aberration-corrected scanning transmission electron microscopy observation found that the basic components of these boundaries are actually terrace-like basal-prismatic interfaces.

Molecular Dynamics Simulations of the Orientation Effect on the Initial Plastic Deformation of Magnesium Single Crystals

“…8e, f. Our simulation result is consistent with the study of Liu et al [31,32] that the B/P transformation is a different mechanism compared with the twinning.…”

“…Guo et al analyzed the deformation mechanisms at the nanoscale for magnesium single crystals under c-axis compression, showing no compression twins occur at different temperatures [29,30]. Recently, the twinning-like lattice reorientation, in which the angle between the basal planes of the parent and the deformed regions was close to 90°, was observed via ½1 100-axis compression experiment and simulation by Liu et al [31,32]. In order to study the competition between the activation of slip systems and deformation twinning, it is therefore of great importance to investigate the orientation effects on deformation mechanisms in magnesium single crystals.…”

Interface structures and twinning mechanisms of twins in hexagonal metals

“…Atomistic simulations confirmed the motion of PB/BP interfaces under a stress normal to the interface [32,58]. Based on these observations, Prism↔Basal transformation mechanism was proposed for twin growth [58,60,93]. The resultant extension strain 6.5% in one direction (Basal → Prism) and contraction strain −6.5% in the orthogonal direction (Prism → Basal) together are equivalent to a shear strain associated with the twinning shear.…”

“…Such a limited height step or the tip of a thin twin has been observed in atomistic simulations [50,51,88] and experiments [63,65]. Figure 12 is a plot of the variation of PB or BP step/facet heights in Mg and Co [60,[62][63][64][65]93,94]. Significantly, many have heights other than the stress-free height: they have Burgers vector content.…”

“…The basis for the proposal is the observation of a PB facet with no other defects present [49]. The TEM micrographs and analysis in [60,[62][63][64][65][93][94][95] show PB facets with varying sizes, Figure 12, many of which are not pure steps, i.e. not 15 or 30 planes high.…”