• Camacho, E.
• Rodrigues, Patricia Freitas
• Santos, Telmo G.
• Inácio, Paulo
• Fernandes, Francisco Manuel Braz

Abstract

AfunctionallygradedNiTishapememoryalloywirewas investigatedbyin-situsynchrotronradiation-basedx-ray diffraction during cyclic tensile deformation. The transfor-mation temperatures were determined by DSC and the ther-momechanical behaviour was analysed by three-point bend-ing. The present study focussed on the localized heat treat-ment(Jouleheateffect,reaching300ºC,350and400ºC pulsesfor10minutes)ofNiTiwires,usinganequipment thatallowsalargevarietyoflocalizedheattreatments. Structural, mechanical and thermomechanical characteriza-tion is presented in order to get a perspective of the optimi-zation parameters for the adequate graded functionality. Ex-perimental results put in evidence the structural gradient re-sulting from thelocalized heat treatments. Theanalysis of the in-situ X-ray diffraction (XRD)provide detailed infor-mation about the phase transformations in different regions of the wire, at differentsteps of the cyclic load/unload, giv-ing a better understanding of the overall mechanical behav-iour of a functionally graded material.

Topics

• impedance spectroscopy
• phase
• x-ray diffraction
• differential scanning calorimetry
• wire