Microstructure evolution in nanocrystalline NiTi alloy produced by HPT

R. Singh*, S. V. Divinski, H. Rösner, E. A. Prokofiev, R. Z. Valiev, G. Wilde

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


A slightly Ni-rich nano-NiTi alloy, deformed by high-pressure torsion (HPT) was investigated. By HPT, almost complete amorphization of initial B2 NiTi is obtained. Crystallization and microstructure evolution during isothermal treatment were investigated by differential scanning calorimetry (DSC) and transmission electron microscopy. The DSC signals observed during continuous heating experiments indicate an unusually large separation between the crystallization and the growth stages. A detailed analysis of the evolution of the enthalpy release upon annealing reveals reproducibly non-monotonous trends with annealing time that cannot be explained solely by growth of crystalline volume fractions. The size of nanocrystals increases dramatically after annealing for 5 h. The effective activation enthalpies for stress relaxation (along with crystallization) and grain growth were estimated at 115 and 289 kJ/mol, respectively. The results are discussed with respect to the intricate interdependencies between synthesis and thermal processing pathways and the evolution of the nanoscale microstructure.

Original languageEnglish
Pages (from-to)S290-S293
JournalJournal of Alloys and Compounds
Issue numberSUPPL. 1
Publication statusPublished - Jul 14 2011
Externally publishedYes


  • Crystallization
  • High pressure torsion
  • Nanocrystalline
  • NiTi
  • Relaxation

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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