Significant disparity of non-basal dislocation activities in hot-rolled highly-textured Mg and Mg-3Al-1Zn alloy under tension

Dexin Zhao, Xiaolong Ma, Abhinav Srivastava, Griffin Turner, Ibrahim Karaman, Kelvin Y. Xie*

*Corresponding author for this work

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

83 Citations (Scopus)

Abstract

It is well-established that Mg-3Al-1Zn (AZ31) alloy exhibits much better tensile ductility than pure Mg. However, the underlying mechanisms for such difference still remain relatively unexplored at the dislocation level. In this work, we deformed hot-rolled highly-textured pure Mg and AZ31 samples with similar initial microstructures (i.e., grain size and texture) under tension along the rolling direction. Apparent shear banding was only observed in the pure Mg samples from the early stage of the deformation. Shear bands could act as easy paths for crack propagation, leading to low ductility in pure Mg. Apparent shear banding was not noted in deformed AZ31 samples. We then investigated the deformation mechanisms at the dislocation level using transmission electron microscopy. Systematic tilting experiments and statistical analyses of multiple grains at different strain levels revealed a significant disparity of non-basal dislocation activities between pure Mg and AZ31. For pure Mg, <c + a> dislocations were activated since the early stage of plastic deformation. For AZ31, <a> dislocations were mostly absent at all strain levels, even in the strain-to-failure samples. Non-basal <a> dislocations, including prismatic and pyramidal <a> dislocations, were observed. The promotion of the non-basal <a> dislocation activities and the suppression of <a> dislocations in AZ31 are expected to offer more sustainable hardening, which could elucidate the absence of apparent shear banding and much-improved ductility in AZ31 compared to pure Mg.
Original languageEnglish
Article number116691
JournalActa Materialia
Volume207
Online published23 Jan 2021
DOIs
Publication statusPublished - 1 Apr 2021
Externally publishedYes

Research Keywords

  • <c + a> dislocation
  • Ductility
  • Mg-3Al-1Zn
  • Non-basal <a> dislocation
  • Pure Mg
  • Shear band

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