Effect of texture heterogeneities on the shape memory properties of rolled Fe- Mn-Si SMA

摘要

We have investigated an Fe-30Mn-4Si shape memory alloy to clarify the effect, onthe bulk texture, of the shear layers resulting from two different thermo-mechanical treat-ments. XR analysis has shown the existence of texture heterogeneity through the rolledsheet's thickness, due to the effect of friction between sheet and rolls. Neutron diffractionrevealed that textured layers on the sheet's surface affect the whole volume. The texturefound on the surface of the sheet rolled at 600°C is the most favourable for the γ→ εmarten-sitic transformation which is the origin of the shape memory effect. Comparing these resultswith those obtained on sheets rolled at room temperature, we found that shear deformationgradients produce changes in the bulk material texture. Tensile tests initially induce themartensitic transformation in those grains favourably oriented. As a result, these favourableorientations disappear in the remnant austenite.