High temperature properties of ductile CuAlNi shape memory alloys with boron additions

Abstract

The use of polycrystalline CuAlNi alloys for high temperature applications is restricted to very small shape changes due to their brittle nature. Additions of alloying elements such as manganese and boron have been introduced to improve the ductility of the material. The behaviour of these alloys has been studied in terms of the influence of these elements on the stability of the microstructure after high temperature annealing or after room and high temperature deformation. The results show that the martensitic structure produced by quenching the alloy from the β-temperature has a lower degree of order than that obtained after further annealing at 300°C for up to an hour. Also, the alloys containing higher boron concentrations present a lower degree of order in all cases. Similarly, the ductility has been much influenced by the boron content. The ductility is greater, in particular at high temperatures, in the alloys with lower concentration of boron.