Guiding severely anisotropic twinning bands in Magnesium: An in situ investigation by full-field microscopic image correlation - Archive ouverte HAL Access content directly
Journal Articles Materials Today Communications Year : 2023

Guiding severely anisotropic twinning bands in Magnesium: An in situ investigation by full-field microscopic image correlation

Abstract

A critical issue for lightweight Magnesium alloys is their propensity for strain localization at the component scale, linked to the peculiar twinning phenomenon. For the (c-axes-aligned) rolling texture, highly compact coordinated twinning bands (CTBs) form that, uniquely, have a singular plane of shear. Normally, where these bands emerge, and progress are up to stochastic factors. Here, a cross-notched sample design is nominated to guide the bands of conjugate orientations into predetermined diagonal corridors and enforce their overlap at a prefixed location. The deformation fields in the Magnesium AZ31 sample are in situ monitored with an advanced microscopic image correlation (micro-DIC) variant that has a unique combination of extreme field coverage (∼1.5 ×10^5 grains), intragranular resolution (∼100 data points per grain) and very high time-step resolution (0.05–0.1% nominal strain increments over the twin plateau). The latter allows investigating the emergence, advance, lateral growth, and interaction of CTBs with extreme detail over absolute and sequential micro-DIC strain maps. The sample design is successful in guiding the CTB formations into the designated corridors. Seed segments of CTBs first make a cross connection across the sample, followed by lateral expansion that proceeds until the corridor is roughly filled. This happens sequentially for the two diagonal corridors, forcing the second band to pass through the first. The band strain is reduced by about 25% at the enforced overlap compared to the characteristic intensity it exhibits outside it (around 2.3%)—a direct measurement of the dilution of the strain activity of a CTB as it crosses another CTB. The uniqueness of this application in guiding severely anisotropic bands is contrasted with the micro-DIC fields of a transversely isotropic sample of the same material that is analogously put under a twin-dominated deformation.
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Dates and versions

hal-04449387 , version 1 (09-02-2024)

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S. Can Erman, Laurent Stainier, C. Can Aydıner. Guiding severely anisotropic twinning bands in Magnesium: An in situ investigation by full-field microscopic image correlation. Materials Today Communications, 2023, 35, pp.106203. ⟨10.1016/j.mtcomm.2023.106203⟩. ⟨hal-04449387⟩
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