Open Access
Article Number 05021
Number of page(s) 8
Section Applied Research and Applications: Engineering Materials with MT
Published online 01 September 2009
ESOMAT 2009, 05021 (2009)
DOI: 10.1051/esomat/200905021

Shape recovery in high temperature shape memory alloys based on the Ru-Nb and Ru-Ta systems

A. Manzoni1, K. Chastaing1, A. Denquin1, P. Vermaut2 and R. Portier2

1  ONERA, 29 Avenue de la Division Leclerc, Châtillon, 92260, France
2  GMS-LPCS UMR CNRS 7045 ChimieParisTech, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05, France

Published online: 1 September 2009

This work investigates the high-temperature behaviour of three RuTa alloys and three RuNb alloys. The first step was to determine how Ta or Nb content affects the MT temperatures. The monoclinic Ru50Ta50 and Ru50Nb50 alloys undergo two successive displacive transformations from the high temperature β phase field: β (B2) → β’ (tetragonal) → β” (monoclinic) whereas Ru45 Nb55 , Ru45Ta55 , Ru43Nb57 , and Ru43Ta57 exhibit a single transition from cubic to tetragonal on cooling. All alloys exhibit a highly twinned microstructure with a (011) compound twinning mode. The main feature of the β’ → β” transformation is the formation of domains boundaries separating translation variants instead of formation of new twin separating orientation variants. The shape memory effect was studied through compression tests performed in the β’ or β” phase. The total shape recovery is mainly due to the β’ → β transformation and appears to decrease from about 3% for the monoclinic alloys to about 0.1% for alloys with 43% Ru in accordance with the evolution of the lattice parameters of martensites.

© Owned by the authors, published by EDP Sciences 2009