Grain orientation dependence of phase transformation in the shape memory alloy Nickel-Titanium

摘要: Abstract The dependence of grain orientation on stress-induced martensitic transformation in superelastic, polycrystalline Nickel–Titanium sheet was examined at the microstructural length scale. Full-field strains, indicative extent, were characterized fields view nominally 100 μm × 100 μm using a custom combination scanning electron microscopy with distortion-corrected digital image correlation. It found that similarly oriented grains do not necessarily transform similarly, contrast to common assumption mean-field theories. Specifically, similar (as determined by misorientation and specimen axes) showed variation both mean strain as well range (heterogeneity) across grain, from surface measurements. Additionally, neither size nor degree (of crystal axes loading axis) affected range.