Microstructure changes during non-conventional heat treatment of thin Ni–Ti wires by pulsed electric current studied by transmissionelectron microscopy

0354464 - FZÚ 2011 RIV GB eng J - Journal Article
Delville, R. - Malard, B. - Pilch, Jan - Šittner, Petr - Schryvers, D.
Microstructure changes during non-conventional heat treatment of thin Ni–Ti wires by pulsed electric current studied by transmissionelectron microscopy.
Acta Materialia. Roč. 58, č. 13 (2010), s. 4503-4513. ISSN 1359-6454. E-ISSN 1873-2453
R&D Projects: GA AV ČR(CZ) IAA200100627
EU Projects: European Commission(XE) 19945 - UPWIND
Institutional research plan: CEZ:AV0Z10100520
Keywords : TEM * heat treatment * SMA * martensitic transformation
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.781, year: 2010
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Transmission electron microscopy, electrical resistivity measurements and mechanical testing were employed to investigate the evolution of microstructure and functional superelastic properties of 0.1 mm diameter as-drawn Ni–Ti wires subjected to a non-conventional heat treatment by controlled electric pulse currents. This method enables a better control of the recovery and recrystallization processes taking place during the heat treatment and accordingly a better control on the final microstructure. Using a stepwise approach of millisecond pulse annealing, it is shown how the microstructure evolves from a severely deformed state with no functional properties to an optimal nanograined microstructure (20–50 nm) that is partially recovered through polygonization and partially recrystallized and that has the best functional properties.
Permanent Link: http://hdl.handle.net/11104/0193460