Influence of Cu addition on transformation temperatures and thermal stability of TiNiPd high temperature shape memory alloys

Saif ur Rehman, Mushtaq Khan, A. Nusair Khan, Khurshid Alam, Syed Husain Imran Jaffery*, Liaqat Ali, Ashfaq Khan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

In this research, four high temperature shape memory alloys, Ti 50 Ni 25-x Pd 25 Cu x (x = 0, 5, 10 and 15) were developed and designated 0Cu, 5 Cu, 10 Cu, and 15Cu, respectively. The effect of 5%, 10%, and 15% (all in atomic percent) Cu addition was investigated through their microstructure analysis, transformation temperatures and thermal stability. After the alloying of Cu content in their desired percentage, the alloys were named as 0Cu, 5Cu, 10Cu and 15Cu alloys. The martensite onset temperature M s of ternary 0Cu alloy increased by 12.5 ℃, 27.5 ℃ and 60.5 ℃, respectively, by replacement of Ni with 5%, 10% and 15% Cu. Similarly, the austenite finish temperature A f increased by 11 ℃, 25 ℃, and 52 ℃, respectively. At the same time, thermal hysteresis of the 5Cu, 10Cu, and 15Cu alloys decreased by 1.5 ℃, 2.5 ℃, and 8.5 ℃, respectively, as compared to 0Cu alloy. The thermal stability of ternary 0Cu alloy was improved by replacing Ni with Cu. During thermal cycling, the net drop in M s and A f of 0Cu alloy was 7.5 ℃ and 14 ℃, respectively. By replacing Ni with 5%, 10%, and 15% Cu, the net drop in M s decreased to 5 ℃, 3.7 ℃, and 3 ℃, respectively, whereas the net drop in A f decreased to 10 ℃, 8.7 ℃, and 5 ℃. The overall results suggested that by the addition of 5%, 10%, and 15% Cu in place of Ni in TiNiPd alloys, the transformation temperatures and thermal stability improved. At the same time, thermal hysteresis decreased to a reasonable level which has a positive effect on the actuation behavior.

Original languageEnglish
Pages (from-to)800-808
Number of pages9
JournalProceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
Volume233
Issue number5
DOIs
Publication statusPublished - May 1 2019

Keywords

  • Martensite start temperature
  • austenite finish temperature
  • high temperature shape memory alloy
  • thermal hysteresis
  • thermal stability

ASJC Scopus subject areas

  • General Materials Science
  • Mechanical Engineering

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