In situ investigation of the fast microstructure evolutionduring electropulse treatment of cold drawn NiTi wires

0358978 - FZÚ 2012 RIV GB eng J - Journal Article
Malard, B. - Pilch, Jan - Šittner, Petr - Delville, R. - Curfs, C.
In situ investigation of the fast microstructure evolutionduring electropulse treatment of cold drawn NiTi wires.
Acta Materialia. Roč. 59, č. 4 (2011), s. 1542-1556. ISSN 1359-6454. E-ISSN 1873-2453
R&D Projects: GA ČR GAP108/10/1296; GA AV ČR(CZ) IAA200100627; GA ČR GAP107/10/0824; GA MŠMT(CZ) LA10010
EU Projects: European Commission(XE) 515813 - AVALON; European Commission(XE) 19945 - UPWIND
Institutional research plan: CEZ:AV0Z10100520
Keywords : shape memory alloys * recovery * recrystallization * Joule heating * superelasticity
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.755, year: 2011

Microstructural changes taking place during the heat treatment of cold-worked NiTi alloy are of key interest in shape memory alloy technology, since they are responsible for setting the austenite shape and functional properties of the heat-treated alloy. In this work, microstructural evolution during non-conventional electropulse heat treatment of thin NiTi filaments was investigated in a unique high-speed in situ synchrotron X-ray diffraction experiment with simultaneous evaluation of the tensile force and electrical resistivity of the treated wire. The in situ results provide direct experimental evidence on the evolution of the internal stress and density of defects during fast heating from 20 C to 700 C. This evidence is used to characterize a sequence of dynamic recovery and recrystallization processes responsible for the microstructure and superelastic functional property changes during the electropulse treatments.
Permanent Link: http://hdl.handle.net/11104/0196866