Martensitic transformation and shape memory effect at high temperatures in off-stoichiometric Co2VSi Heusler alloys

Martensitic transformation in off-stoichiometric Co2VSi Heusler alloy was firstly confirmed in this work. The martensite phase presents an ordered 2M non-modulate D022 structure transformed from L21 Heusler structure. In the Co63.5V17.0Si19.5 alloy, the forward and reverse martensitic transformation temperatures are extremely high which reach up to 683 °C and 693 °C, respectively, higher than most known Heusler-type high-temperature shape memory alloys. And results also indicate that the single martensite phase alloy exhibits a good ductility and strength with the compressive strain of over 15% and strength of about 2300 MPa, respectively. What's more, the recoverable strain being maximal to around 3.1% can be obtained at high temperature (750-800 °C) due to its reverse martensitic transformation.