Toward understanding twin–twin interactions in hcp metals: Utilizing multiscale techniques to characterize deformation mechanisms in magnesium

Transmission Electron Microscope In Situ Straining Technique to Directly Observe Defects and Interfaces During Deformation in Magnesium

“…3 but are consistent with basal dislocations seen in postmortem analysis. 4 Such dislocations have a line direction nearly perpendicular to the plane of the image and appear as a dark point in the images shown. Because of their inconspicuous appearance, they are most apparent when they move, as seen in the supplemental video.…”

“…3,4 The technique itself presents several unique advantages. The most obvious is time resolution of microstructural features.…”

“…Through previous postmortem examinations and current observations, dislocations in the parent matrix are known to lie on basal planes, whereas dislocations within the twinned regions can be either hai-type basal dislocations or hc + ai dislocations lying in other planes. 4 It is reasonable to expect that the interaction between previously existing dislocations in the matrix and an encroaching twin boundary will modify the character of the dislocation as the boundary moves through. Such a mechanism has been proposed by Basinski et al 44 The reaction between a dislocation and a twin boundary should produce dislocation content within the twin, and these dislocations should be sessile.…”

“…Many techniques have been used to probe in situ material response to a stimulus across many length scales, including optical microscopy, 1 scanning electron microscopy (SEM) and transmission electron microscopy (TEM), [2][3][4] and x-ray 5,6 and neutron diffraction. 7,8 Electron microscopy, in particular, is well suited to study materials at the nanoscale.…”

“…Previous studies have used in situ straining to observe twin-twin interactions and characterize twin boundary structure in magnesium and zirconium. 4,34 The current study will also present in situ straining results and will focus on twin interactions with dislocations.…”