Microstructure and shape memory properties of Fe–15Mn–5Si–9Cr–5Ni melt-spun ribbons

At room temperature, conventionally formed Fe–15Mn–5Si–9Cr–5Ni alloys are normally austenitic and the application of a stress induces a reversible martensitic transformation, causing a shape memory effect (SME). However, when the material is processed by a melt-spinning technique, the rapid solidification can stabilize the high-temperature ferritic phase. We found various austenite/ferrite structures in our melt-spun ribbons. The goals of this work were to correlate the process conditions with the resulting phases, find the appropriate heat treatment in order to recover the equilibrium austenitic phase, characterize the different ribbons formed from this material and evaluate the ribbons’ shape memory behaviour. We found that annealing at 1050 °C for 60 min, under a protective argon atmosphere, followed by water quenching, fully retains the austenite to room temperature. We compared particular ribbons, those originally austenitic, to the heat treated ones and analyzed the relationship between yield stress and microstructure and texture. The results from the shape memory tests demonstrate that the ribbons are capable of recovering enough of their shape for certain applications.