Features of a Nanosubgrained Structure in Deformed and Annealed Ti–Ni SMA: A Brief Review

Autor: S. Dubinskiy, Sergey Prokoshkin, Vladimir Brailovski
Rok vydání: 2019
Předmět:
Zdroj: Shape Memory and Superelasticity. 5:336-345
ISSN: 2199-3858
2199-384X
Popis: Important features of a nanosubgrained structure in Ti–Ni shape memory alloys (SMA) are considered. The thermomechanical treatment of Ti–Ni SMA comprising cold rolling (CR) and post-deformation annealing (PDA) forms a nanocrystalline structure (NCS) providing much higher functional properties than normal coarse-grained structure. The NCS consisting of grains surrounded by high-angle boundaries (“nanograined structure,” NGS) provides higher static shape memory properties than the NCS consisting of subgrains separated by low-angle ( 1) levels, the NSS transforms to the mixed NSS + NGS and then to the NGS. The NS structures observed in Ti–Ni after intermediate or severe CR and after PDA do not significantly differ from each other in TEM images. This is due to the development of dynamic polygonization during CR which continues as the static polygonization during PDA. A moderate CR does not reach the dynamic polygonization stage, its dislocation substructure transforms to a statically polygonized NSS upon PDA.
Databáze: OpenAIRE
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