In situ observation of collective grain-scale mechanics in Mg and Mg–rare earth alloys

Local Plastic-Strain Heterogeneities and Their Impact on the Ductility of Mg

“…11. This observation is consistent with those of Wang et al, 17 who recently observed localized slip activity causing the formation of a preshear band due to percolated basal slip activity. From Fig.…”

“…The CorrelManuV (CMV) DIC software [17][18][19][20][21][22] was used to correlate the grids from undeformed and deformed regions using a 30 9 30 pixel correlation subset and a 15 9 15 pixel search domain. Bilinear interpolation of grayscale was used to allow an accuracy of 0.1 pixel in displacement.…”

“…3. Indeed, checking the orientation of the grain in zone 1 it was found that it was oriented with [0001] within 2°of the normal (ND) direction [11][12][13][14][15][16][17][18][19][20] and with ½1120 within 3°of the TD. It was found that the experimentally measured strain tensor using the same coordinate system within the feature was consistent with the theoretical strain tensor given above.…”

“…At a more mesocopic scale, magnesium and magnesium alloys form shear bands; 6,16,17 this is particularly apparent in plane strain compression (e.g., rolling). Strain rapidly accumulates into such shear bands, resulting in narrow regions of intense local strain (the shear bands) where damage develops and leads to complete fracture.…”

Origin of the twinning to slip transition with grain size refinement, with decreasing strain rate and with increasing temperature in magnesium

“…To our knowledge, however, no studies in the past have quantified the correlations between the rolling and extrusion processing parameters and the percolation properties of the resulting GB networks in pure Mg and in Mg alloys. Nevertheless, it is known that clusters of grains well oriented for basal slip do form during rolling and extrusion of Mg alloys at low to moderate temperatures [55][56][57], while subsequent annealing at higher temperatures leads to the preferential growth of grains with c-axes parallel to the rolling plane or, respectively, perpendicular to the extrusion direction. Thus, it seems logical to presume that the connectivity of the clusters of grains favorably oriented for basal slip decreases with increasing d in most of the works in which polycrystals were processed using these conventional processing routes, as demonstrated in the present study.…”