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 beta'(1) and little gamma'(1) martensites, and x=2 only shows dominant gamma'(1) martensite. Small amounts of alpha(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 beta'(1) and gamma'(1) martensites, and the snowflake-shaped gamma(1) (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%. (C) 2014 Elsevier B.V. All rights reserved.