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

  • Mahdi Moshref Javadi
  • Majid Belbasi
  • Mohammad T. SalehiEmail author
  • M. Reza Afshar


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.


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


  1. 1.
    K. Otsuka and X. Ren, Physical Metallurgy of Ti-Ni-Based Shape Memory Alloys, Prog. Mater. Sci., 2005, 50, p 511–678CrossRefGoogle Scholar
  2. 2.
    X.D. Han, R. Wang, Z. Zhang, and D.Z. Yang, A New Precipitate Phase in a TiNiHf High Temperature Shape Memory Alloy, Acta Mater., 1998, 46, p 273–281CrossRefGoogle Scholar
  3. 3.
    G.S. Firstov, J.V. Humbeeck, and Y.N. Koval, High-Temperature Shape Memory Alloys: Some Recent Developments, Mater. Sci. Eng. A, 2004, 378, p 2–10CrossRefGoogle Scholar
  4. 4.
    P.L. Potapov, A.V. Shelyakov, A.A. Gulyaev, E.L. Svistunova, N.M. Matveeva, and D. Hodgson, Effect of Hf on the Structure of Ni-Ti Martensitic Alloys, Mater. Lett., 1997, 32, p 247–250CrossRefGoogle Scholar
  5. 5.
    X.L. Meng, W. Cai, L.M. Wang, Y.F. Zheng, L.C. Zhao, and L.M. Zhou, Microstructure of Stress-Induced Martensite in a Ti-Ni-Hf High Temperature Shape Memory Alloy, Scr. Mater., 2001, 45, p 1177–1182CrossRefGoogle Scholar
  6. 6.
    W. Cai, X.L. Meng, and L.C. Zhao, Recent Development of TiNi-Based Shape Memory Alloys, Curr. Opin. Solid State Mater. Sci., 2005, 9, p 296–302CrossRefGoogle Scholar
  7. 7.
    X.L. Meng, W. Cai, L.M. Wang, Y.F. Zheng, and L.C. Zhao, Shape Memory Properties of the Ti36Ni49Hf15 High Temperature Shape Memory Alloy, Mater. Lett., 2000, 45, p 128–132CrossRefGoogle Scholar
  8. 8.
    Y.Q. Wang, Y.F. Zheng, and L.C. Zhao, The Tensile Behavior of Ti36Ni49Hf15 High Temperature Shape Memory Alloy, Scr. Mater., 1999, 40, p 1327–1331CrossRefGoogle Scholar
  9. 9.
    C. Craig Wojcik, Properties and Heat Treatment of High Transition Temperature Ni-Ti-Hf Alloys, Mater. Eng. Perform., 2009, 18, p 511–516CrossRefGoogle Scholar
  10. 10.
    X.L. Meng, W. Cai, Y.D. Fu, Q.F. Li, J.X. Zhang, and L.C. Zhao, Shape-Memory Behaviors in an Aged Ni-Rich TiNiHf High Temperature Shape-Memory Alloy, Intermetallics, 2008, 16, p 698–705CrossRefGoogle Scholar
  11. 11.
    P.E. Thoma and J.J. Boehm, Effect of Composition on the Amount of Second Phase and Transformation Temperatures of NixTi90-xHf10 Shape Memory Alloys, Mater. Sci. Eng. A, 1999, 273, p 385–389CrossRefGoogle Scholar
  12. 12.
    Y. Tong, F. Chen, B. Tian, and Y. Zheng, Microstructure and Martensitic Transformation of Ti49Ni51-xHfx High Temperature Shape Memory Alloys, Mater. Lett., 2009, 63, p 1869–1871CrossRefGoogle Scholar
  13. 13.
    S. Besseghini, E. Villa, and A. Tuissi, Ni-Ti-Hf Shape Memory Alloy: Effect of Aging and Thermal Cycling, Mater. Sci. Eng. A, 1999, 273, p 390–394CrossRefGoogle Scholar
  14. 14.
    S. Han, W. Zou, S. Jin, Z. Zhang, and D. Yang, The Studies of the Martensite Transformations in a Ti36.5Ni48.5Hf15 Alloy, Scr. Mater., 1995, 32, p 1441–1446CrossRefGoogle Scholar
  15. 15.
    X.L. Meng, Y.F. Zheng, Z. Wang, and L.C. Zhao, Effect of Aging on the Phase Transformation and Mechanical Behavior of Ti36Ni49Hf15 High Temperature Shape Memory Alloy, Scr. Mater., 2000, 42, p 341–348CrossRefGoogle Scholar
  16. 16.
    S. Shirnizu, Y. Xu, S. Tanaka, K. Otsuka, and K. Mitose, Improvement of Shape Memory Characteristics by Precipitation-Hardening of Ti-Pd-Ni Alloys, Mater. Lett., 1998, 34, p 23–29CrossRefGoogle Scholar

Copyright information

© ASM International 2011

Authors and Affiliations

  • Mahdi Moshref Javadi
    • 1
  • Majid Belbasi
    • 1
  • Mohammad T. Salehi
    • 1
    Email author
  • 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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