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Microstructural characterization of NiTi shape memory alloy produced by rotary hot forging

Published online by Cambridge University Press:  29 May 2017

P. Rodrigues*
Affiliation:
CENIMAT, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal
F. M. Braz Fernandes
Affiliation:
CENIMAT, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal
A. S. Paula
Affiliation:
Mechanical Engineering and Materials Department-SE-4, Instituto Militar de Engenharia–IME, Brazil Metallurgical Engineering Post-Graduation Program (PPGEM), Universidade Federal Fluminense (UFF), Brazil
J. P. Oliveira
Affiliation:
CENIMAT, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal
S. B. Ribeiro
Affiliation:
Centro Universitário de Volta Redonda – UNIFOA, Brazil
E. N. Texeira
Affiliation:
Centro Universitário de Volta Redonda – UNIFOA, Brazil
N. Schell
Affiliation:
HZG, Geesthacht, Germany
*
a)Author to whom correspondence should be addressed. Electronic mail: [email protected]

Abstract

The thermomechanical processing of NiTi shape memory alloys usually involves several steps of hot and/or cold deformation. The present work presents the structural characterization of a Ni-rich NiTi alloy bar, produced by vacuum-induced melting and thermomechanical processing in laboratory scale, aiming at massive production in the future. This study focused on the first step of hot working at 800 °C during rotary forging. Microstructural characterization was performed using differential scanning calorimetry, high- and low-temperature X-ray diffraction (XRD) using a laboratory source and synchrotron XRD. Thus, it was possible to obtain the phase transformation characteristics of the material: the transformation temperatures and the transformation sequence. Proposed thermomechanical processing is intended for production of bars and wires that will be subsequently drawn to get thin wires, for different applications, including orthodontic arch wires.

Type
Technical Articles
Copyright
Copyright © International Centre for Diffraction Data 2017 

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