Characterization of phase transformations, long range order and thermal properties of Ni2MnGa alloys

Hideki Hosoda, Tsuyoshi Sugimoto, Kenji Ohkubo, Seiji Miura, Tetsuo Mohri, Shuichi Miyazaki

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

Martensitic and magnetic transformation temperatures were investigated for Ni2MnGa alloys as a function of the degree of long-range order (LRO) associated with L21 structure. The degree of order was changed by changing the heat treatment temperature. Besides, thermal properties such as thermal expansion (CTE), specific heat (Cp) and thermal conductivity (λ) were measured up to 1273 K. It was found that with increasing the heat treatment temperature, the degree of second neighbor ordering lowered, but that the degree of first neighbor ordering did not show good correlations with the heat treatment temperatures. Martensitic transformation temperature (Ms) and Curie temperature (Tc) vary with the square of the degree of LRO. Cp and λ at room temperature are 29.5 Jmol-1K-1 and 23.2 Wm-1K-1. CTE is ranged between 15 × 10-6K-1 and 34 × 10-6K-1. Temperature dependence of these thermal properties is described.

Original languageEnglish
Pages (from-to)9-17
Number of pages9
JournalInternational Journal of Applied Electromagnetics and Mechanics
Volume12
Issue number1-2
DOIs
Publication statusPublished - 2000

Keywords

  • Curie temperature
  • Heat treatment
  • L2 structure
  • Long range order
  • Martensitic transformation temperature
  • NiMnGa
  • Specific heat
  • Thermal expansion

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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