Grain size refinement in Mg-Al-based alloy by hydrogen treatment

H. Takamura, T. Miyashita, A. Kamegawa, M. Okada

Research output: Contribution to journalConference articlepeer-review

42 Citations (Scopus)


The present paper describes the grain size refinement of AZ31 alloys by means of the HDDR process. Hydrogenation was carried out at 250̃450°C under a hydrogen pressure of 7 MPa for 24̃36 h. Upon hydrogenation, the disproportionation reaction occurred, leading to the formation of MgH2, Mg0.42Al0.58, and Al phases. In the subsequent desorption process, the three phases were recombined, and the AZ31 alloy was recovered. As a result of the HDDR process, the grain size of the AZ31 alloy powders was reduced from 50̃300 μm to about 100 nm in the case of the heat treatment at 350°C under a hydrogen pressure of 7 MPa for 24 h. The grain size tended to be increased with increasing process temperatures. In addition, the HDDR process was also applied to AZ31 alloy plates. By means of the HDDR process at 450°C, the grain size was reduced to less than 500 nm, while the layer thickness being treated was limited to the range of about 20 μm from the surface after 36 h at 7 MPa pressure of H2.

Original languageEnglish
Pages (from-to)804-808
Number of pages5
JournalJournal of Alloys and Compounds
Publication statusPublished - 2003 Aug 11
EventProceedings of the Eight International Symposium on Metal Hyd (MH 2002) - Annecy, France
Duration: 2002 Sep 22002 Sep 6


  • Gas-solid reactions
  • Grain-size refinement
  • HDDR phenomena
  • Transmission electron microscopy
  • X-Ray diffraction

ASJC Scopus subject areas

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


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