Martensitic transformation and shape memory effect in ausaged Fe-Ni-Si alloys

Yoshiyuki Himuro, Ryosuke Kainuma, Kiyohito Ishida

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

Martensitic transformations in the Fe-(24-30)Ni-(5-8)Si (mass%) alloys have been investigated by means of optical and transmission electron microscopy, differential scanning calorimetry and hardness-testing. The Ms temperature is decreased by Si addition and the morphology of martensite is mainly lenticular in the unaged specimens. However, a pronounced decrease in the Ms temperature and a change in the martensite morphology from the lenticular to the thin plate type are observed on ausaging at 400°C. The increase in austenite hardness, the decrease in the Ms temperature and the increase in the tetragonality of martensite after ausaging at 400°C are clarified as due to the formation of nanoscale particles of γ′-(Ni, Fe)3Si with the L1 2 structure during ausaging at 400°C. The Fe-Ni-Si alloys that form thin plate martensite show the shape memory effect, which arises from the reverse transformation of stress-induced martensite to austenite. Precipitation hardening of the austenite phase by fine γ′ particles during ausaging improves the degree of shape recovery.

Original languageEnglish
Pages (from-to)184-190
Number of pages7
JournalIsij International
Volume42
Issue number2
DOIs
Publication statusPublished - 2002 Feb

Keywords

  • Ausaging
  • Fe-Ni-Si alloy
  • Martensitic transformation
  • Precipitation
  • Shape memory effect
  • Thin-plate martensite

ASJC Scopus subject areas

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

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