Characterization of an Fe-Mn-Si-Cr-Ni shape memory alloy by X-ray diffraction and Electron Backscatter Diffraction

V. FUSTER, M. AVALOS, A. DRUKE, R. BOLMARO, J. MALARRIA

Concepción

Congreso; 15 º Congreso Binacional de Metalurgia y Materiales CONAMET-SAM; 2015

Sociedad Chilena de Metalurgía y Materiales (SOCHIM)

The shape memory effect (SME) of Fe-based alloys is due to areversible martensitic transformation g (FCC) ↔ e (HCP), induced by stress and reverted by heat-treatment above Af.In this condition, the martensitic variants most favorable oriented with respectto the applied stress axis develop. Numerous studies suggest that theimprovement of the SME can be achieved by controlling the materialmicrostructural properties, namely by grain size refinement, austenitic matrixstrengthening as a result of increasing dislocation and twin densities, as wellas introducing a convenient preferential orientation (texture). In this work weidentify and quantify the present phases, and analyze the microstructure of an Fe-15Mn-5Si-9Cr-5Nimass % (nominal composition) shape memory alloy (SMA) in two states: (1)hot-rolled at 1000 and 800 °C in successive passes with a 10 % rollingreduction per pass, to 1 mm final thickness, and recovery annealed at 650 °Cfor 30 min; and (2) tensile tested to 4.6 % final strain. In both cases thematerial characterization was done by X-ray diffraction (XRD) and Rietveldrefinement using Maud, and by Electron Backscatter Diffraction (EBSD). Wediscuss and correlate the experimental results obtained by both techniques.