Influence of Ga on martensitic and magnetic transitions in Co-Ni-Al β-based ferromagnetic shape memory alloys

Guo Fu Xu, Zhi Min Yin, Feng Hua Luo, Shen Zhou Mou, K. Oikawa

Research output: Contribution to journalArticle

Abstract

The influences of gallium concentration on martensitic transformation temperature and Curie point of Co41Ni32Al27-xCax alloys were investigated by optical micrography, scanning electron microscopy, differential scanning calorimetry and vibrating sample magnetometer and energy dispersive X-ray detector. The results show that the martensitic transformation temperatures of Co41Ni32Al27-xGax alloys are linearly increased with Ga content. An increase of 1% in Ga concentration can cause the martensitic transformation temperature to be increased by 25 K for alloys quenched at 1623 K or at 1573 K, respectively. The influence on Curie points of Co41Ni31-Al27-xGax alloys is very small. However, the order degree of phase structure has great effects on Curie point. The Curie point of high ordered martensitic phase is higher than that of B2 structure phase by 32 K. Martensitic transformation temperatures increase by 43-69 K and Curie points increase by 41 K when the quenched temperatures elevate from 1573 to 1623 K. The melting points of Co41Ni32Al27-xGax alloys decrease with the increase of Ga concentration, resulting in the partial melted phenomena of Co41Ni32Al18Ga7 alloy quenched at 1623 K.

Original languageEnglish
Pages (from-to)635-640
Number of pages6
JournalZhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology)
Volume37
Issue number4
Publication statusPublished - 2006 Aug 1

Keywords

  • Co-Ni-Al-Ga alloy
  • Curie point
  • Magnetism
  • Martensitic transformation

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Geotechnical Engineering and Engineering Geology
  • Metals and Alloys
  • Materials Chemistry

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