Microstructure and properties of Cu–Al–Fe high-temperature shape memory alloys

The microstructure, martensitic transformation, mechanical and shape memory properties of Cu84−xAl11+xFe5 (x = 0, 1, 2) alloys under the quenched and aged states were investigated. The results show that x = 0 and 1 under the quenched state exhibit a mixture of primary β′1 and little γ′1 martensites, and x = 2 only shows dominant γ′1 martensite. Small amounts of α(Cu) and Fe(Al,Cu) phases are observed for x = 0, whereas only tiny Fe(Al,Cu) phase exists for x = 1. After aging, all alloys have a mixture of β′1 and γ′1 martensites, and the snowflake-shaped γ1 (Cu9Al4) precipitate is present for x = 2. The recovery strain and ratio for x = 0 and 2 remarkably decrease after aging due to the precipitations. However, the recovery strain of x = 1 after aging still linearly increases with the increase of the pre-strain, up to a maximum value of 1.6%.