Improvement of hardness and microstructures by ageing in shape memory CuAlNi alloys


Creative Commons License

Aydogdu A. , Aydogdu Y. , Adiguzel O.

JOURNAL DE PHYSIQUE IV, vol.7, pp.311-316, 1997 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 7
  • Publication Date: 1997
  • Doi Number: 10.1051/jp4:1997549
  • Title of Journal : JOURNAL DE PHYSIQUE IV
  • Page Numbers: pp.311-316

Abstract

The shape memory CuAlNi alloys, having a composition near that of Cu,AI, exhibit disorder-order transition from the disordered bce beta-phase to the ordered beta(1)-phase (DO3 type) at high temperatures. Although the beta(1)-phase is a non-equilibrium phase, it nonetheless remains stable at room temperature upon quenching from the high temperature beta-phase. At the lower temperatures, the beta(1)-phase itself undergoes martensitic transformation and displays layered structure called M18R. The influence of ageing on two CuAlNi beta-phase alloys was studied by measuring the time dependence of hardness, lattice parameters and by optical microscopy observation al room temperature. Hardness shows a trend to decrease with the ageing duration due to the formation of precipitation and grain size is also affected by ageing.