Effect of rapid solidification on mechanical properties of Cu-Al-Ni shape memory alloys

Abstract

Mechanical properties of β-phase shape memory alloys with the addition of small amounts of chromium or zirconium were studied at various temperatures. In addition to the conventional casting process, Cu-Al-Ni-Zr alloys were produced by rapidly solidified processes, including the gas atomization and melt spinning methods. Buck materials were also made by hot-press sintering from the Cu-Al-Ni-Zr alloy powders and chopped ribbons. It was found that the brittleness of Cu-Al-Ni alloys was improved by the addition of either chromium or zirconium. It is suggested that this improvement is due to increase of grain-boundary strength, not just because of grain refining. The better mechanical properties were obtained in the rapidly solidified and sintered alloys which show fine grain size, fracture strength as high as 780 MPa and 7% fracture strain.