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Item type:Publication, Access status: without files , On the Influence of Twinning and Detwinning on the Deformation of Mg at the Micron ScaleThe influence of twinning and detwinning on the constitutive mechanical response of Mg was investigated via microcompression tests of single-crystalline pillars of nominal [0001] and [10-10] orientations, and bicrystalline pillars containing a single twin boundary. The [0001] pillars exhibit the highest initial yield strength while the [10-10] and bicrystalline pillars initially yield at significantly lower stress, at which twin nucleation and growth or migration commence. Depending on the extent of straining, the [10-10] and bicrystalline pillars exhibit a secondary yield point associated with the deformation of the newly formed [0001] oriented pillar. The mechanical results point to an anisotropy in the mechanical consequence of twin motion, as characterized through the comparison of the three micropillar orientations; a twin-mediated hardening is indicated by the relative stress-strain behavior.Publicationtype: Conference Paper115 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Detwinning-mediated hardening in Mg: A microcompression study of a single twin boundary(2020-01-20); ; We present the first experimental measurement of the hardening arising from the detwinning of a single twin boundary in Mg. Microcompression tests were performed on two sets of microcolumns: (i) single crystals having a “parent” grain orientation of nearly (0 0 0 1) along the compression axis, and (ii) bicrystals involving the parent grain and a single 101‾2 twin boundary. A comparison of the stress-strain data shows significant differences in the deformation characteristics of the deformed microcolumns. The bicrystalline microcolumns undergo detwinning, as indicated by a stress plateau, which leads to a nominally single crystalline microcolumn of the orientation of the parent grain. Microcompression beyond the plateau shows that the detwinned microcolumns exhibit a considerably higher yield stress and strain hardening rate than the single crystalline “parent” microcolumns. Electron back-scattered diffraction analyses on the cross-sections of the deformed microcolumns reveal higher misorientations in the detwinned region indicative of a high content of unpaired dislocations (so-called GNDs), compared to the deformed parent microcolumns. This discrepancy in misorientation distribution between the samples is consistent with a detwinning-mediated hardening response, as observed, and points to the creation of dislocation debris as a consequence of the detwinning process.Publicationtype: Journal Article166