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Characterization of TiNi shape memory alloys obtained by spark plasma sintering process

C. D. CIRSTEA1, F. TOLEA2, L. LEONAT1, M. LUNGU1, A. CUCOS1, V. CIRSTEA3, V. TSAKIRIS1

Affiliation

  1. National Institute for Research and Development in Electrical Engineering INCDIE ICPE-CA, Splaiul Unirii 3,030121, Bucharest, Romania
  2. National Institute for Materials Physics, Atomistilor 105bis, 077125 Magurele, Ilfov, Romania
  3. Military Equipments and Technology Research Agency, Aeroportului, 16, 077025 Clinceni Ilfov, Romania

Abstract

This paper presents the research results on the thermal behavior of the 48.5%at.Ti-Ni alloys, obtained by spark plasma sintering in vacuum under a pressure of 50 MPa, at temperatures of 850ºC and 900ºC and holding time of 5 minutes, and subsequently aged in argon for up to 30 minutes at 450ºC. Differential scanning calorimetry, dynamic mechanical and dilatometry analysis were used to characterize the transformation properties of the TiNi samples. All the results of differential scanning calorimetry and dynamic mechanical analysis confirmed the hypothesis that the stress-free thermally induced martensitic transformation exists in the investigated TiNi alloys. Annealing at lower temperatures (450ºC) in Ni-rich TiNi alloys led to precipitation process which facilitates the formation of the R-phase due to internal stress contributed by precipitates..

Keywords

TiNi, Calorimetry, Dynamic mechanical analysis, Dilatometry.

Submitted at: Sept. 1, 2015
Accepted at: Sept. 29, 2016

Citation

C. D. CIRSTEA, F. TOLEA, L. LEONAT, M. LUNGU, A. CUCOS, V. CIRSTEA, V. TSAKIRIS, Characterization of TiNi shape memory alloys obtained by spark plasma sintering process, Journal of Optoelectronics and Advanced Materials Vol. 18, Iss. 9-10, pp. 857-862 (2016)