On the Impact of γ´ Precipitates on the Transformation Temperatures in Fe–Ni–Co–Al–Ti–B Shape Memory Alloy Wires

Abstract

The effect of precipitation on the martensitic transformation temperatures of cold drawn Fe41–Ni28–Co17–Al11.5–Ti2.5-B0.05 (at. %) wires was studied. To promote the evolution of γ´ precipitates ageing at 600 °C, 650 °C and 700° for times varying between 1 and 24 h was performed. Variation in the size and distribution of the precipitates via ageing significantly affects the transformation temperatures as the Ni content in the matrix is altered. The different sizes and distributions of the precipitates affects the austenite finish temperature, which is around room temperature and canbe modified by approximately 100 °C.