High temperature shape memory alloys

Abstract

Shape memory alloys (SMAs) with high transformation temperatures can enable simplifications and improvements in operating efficiency of many mechanical components designed to operate at temperatures above 100°C, potentially impacting the automotive, aerospace, manufacturing and energy exploration industries. A wide range of these SMAs exists and can be categorised in three groups based on their martensitic transformation temperatures: group I, transformation temperatures in the range of 100-400°C; group II, in the range of 400-700°C; and group III, above 700°C. In addition to the high transformation temperatures, potential high temperature shape memory alloys (HTSMAs) must also exhibit acceptable recoverable transformation strain levels, long term stability, resistance to plastic deformation and creep, and adequate environmental resistance. These criteria become increasingly more difficult to satisfy as their operating temperatures increase, due to greater involvement of thermally activate...