In Situ Characterization of the Effect of Twin-Microstructure Interactions on {1 0 <span style="text-decoration: overline">1</span> 2} Tension and {1 0 <span style="text-decoration: overline">1</span> 1} Contraction Twin Nucleation, Growth and Damage in Magnesium
William D. Russell,
Nicholas R. Bratton,
YubRaj Paudel,
Robert D. Moser,
Zackery B. McClelland,
Christopher D. Barrett,
Andrew L. Oppedal,
Wilburn R. Whittington,
Hongjoo Rhee,
Shiraz Mujahid,
Bhasker Paliwal,
Sven C. Vogel,
Haitham El Kadiri
Affiliations
William D. Russell
Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762, USA
Nicholas R. Bratton
Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762, USA
YubRaj Paudel
Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762, USA
Robert D. Moser
U.S. Army Corps of Engineers, Engineer Research and Development Center, Vicksburg, MS 39180, USA
Zackery B. McClelland
U.S. Army Corps of Engineers, Engineer Research and Development Center, Vicksburg, MS 39180, USA
Christopher D. Barrett
Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762, USA
Andrew L. Oppedal
Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762, USA
Wilburn R. Whittington
Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762, USA
Hongjoo Rhee
Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762, USA
Shiraz Mujahid
Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762, USA
Bhasker Paliwal
Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762, USA
Sven C. Vogel
Materials Science & Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
Haitham El Kadiri
Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762, USA
Through in situ electron backscatter diffraction (EBSD) experiments, this paper uncovers dominant damage mechanisms in traditional magnesium alloys exhibiting deformation twinning. The findings emphasize the level of deleterious strain incompatibility induced by twin interaction with other deformation modes and microstructural defects. A double fiber obtained by plane-strain extrusion as a starting texture of AM30 magnesium alloy offered the opportunity to track deformation by EBSD in neighboring grains where some undergo profuse {1 0 1 2} twinning and others do not. For a tensile loading applied along extrusion transverse (ET) direction, those experiencing profuse twinning reveal a major effect of grain boundaries on non-Schmid behavior affecting twin variant selection and growth. Similarly, a neighboring grain, with its 〈c〉-axis oriented nearly perpendicular to tensile loading, showed an abnormally early nucleation of {1 0 1 1} contraction twins (2% strain) while the same {1 0 1 1} twin mode triggering under 〈c〉-axis uniaxial compression have higher value of critical resolved shear stress exceeding the values for pyramidal 〈c + a〉 dislocations. The difference in nucleation behavior of contraction vs. compression {1 0 1 1} twins is attributed to the hydrostatic stresses that promote the required atomic shuffles at the core of twinning disconnections.
