Hot Rolling Effects on the Microstructure and Chemical Properties of NiTiTa Alloys

In the present paper, a Ni-37Ti-15Ta (wt.%) shape memory alloy was analyzed in as-cast and hot-rolled conditions, by differential scanning calorimetry, scanning electron microscopy coupled with energy-dispersive spectroscopy, x-ray diffraction and electrochemical tests into a simulated body fluid (S...

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Bibliographic Details
Published in:	Journal of materials engineering and performance 2019-12, Vol.28 (12), p.7273-7280
Main Authors:	Lohan, N. M., Pricop, B., Popa, M., Matcovschi, E., Cimpoeşu, N., Cimpoeşu, R., Istrate, B., Bujoreanu, L. G.
Format:	Article
Language:	eng
Subjects:	Characterization and Evaluation of Materials Chemistry and Materials Science Corrosion and Coatings Engineering Design Materials Science Quality Control Reliability Safety and Risk Tribology
Online Access:	Get full text
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Summary:	In the present paper, a Ni-37Ti-15Ta (wt.%) shape memory alloy was analyzed in as-cast and hot-rolled conditions, by differential scanning calorimetry, scanning electron microscopy coupled with energy-dispersive spectroscopy, x-ray diffraction and electrochemical tests into a simulated body fluid (SBF). Both processing states experienced reversible martensitic transformations, with lower temperatures of reverse transformation at hot-rolled specimen, where the amount of secondary phases suffered contrary variation tendencies: β-Ta solid solution increased and (Ti,Ta) 2 Ni intermetallic compound decreased. Hot rolling contributed to the increase in internal stresses which caused a slight decrease of 2 θ angle and to the stress-induced formation of B19’ martensite from B2 parent phase. The electrochemical corrosion test, performed in an experimental SBF, emphasized the superior corrosion resistance of as-cast specimen, since it had a lower amount of internal stresses. The corrosion compounds, mostly oxides, were completely removed by ultrasonic cleaning.
ISSN:	1059-9495 1544-1024