Recovery stress formation in FeMnSi based shape memory alloys: Impact of precipitates, texture and grain size

Highlights: • Precipitates increased the recovery stress in FeMnSi based alloys by affecting the strength and the shape memory properties. • A maximum recovery stress of 564 MPa is achieved by using precipitates. • The [001] texture component with a low shape memory effect but a high yield strength increases the recovery stress. • Decreasing the grain size did not affect the recovery stress, but for a decrease of grain size pseudo-elasticity increased. FeMnSi based shape memory alloys are considered for engineering applications such as prestressing of concrete or coupling devices. For this, a high recovery stress is desired which forms when the FeMnSi alloy is first elongated and then heated above the austenite transformation temperature under mechanical constraints. In this work, we study the impact of three different microstructural properties on the recovery stress of Fe17Mn5Si10Cr4Ni1(V,C) shape memory alloys: Precipitates, texture and grain size. Precipitates allowed varying the recovery stress in a broad range between 255 MPa and 564 MPa. A recovery stress of 564 MPa was achieved by a combination of a high materials yield strength σ_0.1 of 536 MPa and a shape recovery of 14%. The [001] grain orientation with a low Schmid factor has a beneficial impact on the recovery stress due to a higher yield strength when compared with the [011] orientation. A decrease of the grain size caused a Hall-Petch strengthening but had no influence on the recovery stress. However the pseudo-elasticity increased for a decrease of grain size.