Cyclic deformation and austenite stabilization in Co₃₅Ni₃₅Al₃₀ single crystalline high-temperature shape memory alloys

authored by

J. Dadda, H. J. Maier, I. Karaman, Y. I. Chumlyakov

Abstract

This study reports on the role of repeated stress-induced martensite (SIM) transformations on the pseudoelastic (PE) behavior of solutionized Co₃₅Ni₃₅Al₃₀ [0 0 1]-oriented shape memory single crystals under both isothermal and non-isothermal conditions (referred to as "training"). It is demonstrated that training results in austenite stabilization and strengthening, consequently increasing the critical transformation stress levels for the SIM (σ_crit^SIM), and promoting excellent cyclic stability and reproducibility of the PE response. This is attributed to the formation of dense dislocation arrangements and fine coherent sub-nanometer hexagonal close-packed Co and γ′ (Ni₃Al:L1₂) precipitates during training. The training that involved cyclic loading conditions was more effective than the monotonic stress-strain tests at different temperatures in modifying SIM characteristics bringing about (i) a large pseudoelastic temperature range of 350 °C with σ_crit^SIM levels reaching 1 GPa with complete recoverable strains of 2%, and (ii) excellent stable cyclic PE response at temperatures as high as 250 °C.

External Organisation(s)

Paderborn University
Texas A and M University
Tomsk State University

Type

Article

Journal

Acta materialia

Volume

57

Pages

6123-6134

No. of pages

12

ISSN

1359-6454

Publication date

12.2009

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Ceramics and Composites, Polymers and Plastics, Metals and Alloys

Electronic version(s)

https://doi.org/10.1016/j.actamat.2009.08.038 (Access: Unknown)