High temperature Cu-Al-Nb - based shape memory alloys

Abstract
New type of Cu-Al-Nb - base alloys containing nickel, cobalt and chromium with high martensitic transformation temperatures have been developed. In this paper the mechanical properties, shape memory characteristics, the temperatures of reversible martensitic transformation and thermal stability of these alloys are presented. Introducing chromium and specially nickel and cobalt to the Cu-Al-Nb alloys gives a possibility to decrease the characteristic temperatures. However, these elements create in the martensitic matrix primary particles of intermetallic phases such as AlCo and NiAl and change the chemical composition of the Nb(,Al,Cu)₂ - the main phase in the ternary Cu-Al-Nb alloy. Presence of precipitates results in decrease of the elongation of these alloys. Nickel and cobalt improve the thermal stability and resistance to decomposition.