Effect of Aging on the Microstructure and Shape Memory Effect of a Hot-Rolled NiTiHf Alloy

  • Mahdi Moshref Javadi
  • Majid Belbasi
  • Mohammad T. Salehi
  • M. Reza Afshar
Article

Abstract

In this article, the effect of aging on the microstructure and shape memory effect (SME) of a hot-rolled Ni49Ti36Hf15 alloy is studied. The alloy was prepared by vacuum induction melting (VIM) and homogenized at 1000 °C for 2 h. The homogenized alloy was then undergone 45% hot rolling at 850 °C and aging at temperatures of 500 and 600 °C for 2 h. Optical microscopy (OM) and scanning electron microscopy (SEM) conducted on the hot-rolled samples revealed that hot rolling improves microstructure, deformation, and recoverable strains such that the alloy recovers 3.10 of 3.23 and 5.61 of 6.25 strain in the homogenized and hot-rolled state, respectively. Aging, however, adversely affects the formability and SME of the alloy, which stems from the embrittling effect of the newly formed precipitates during the aging process.

Keywords

high-temperature shape memory alloy hot rolling microstructure Ni-Ti-Hf shape memory effect 

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Copyright information

© ASM International 2011

Authors and Affiliations

  • Mahdi Moshref Javadi
    • 1
  • Majid Belbasi
    • 1
  • Mohammad T. Salehi
    • 1
  • M. Reza Afshar
    • 2
  1. 1.School of Metallurgy and Materials EngineeringIran University of Science and TechnologyTehranIran
  2. 2.Department of Materials Engineering, Science and Research BranchIslamic Azad UniversityTehranIran

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