Microstructures of hydrogen absorbing Zr0.5Ti0.5MnV multiphase alloys

Hideki Iba, Etsuo Akiba

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Abstract

AB2 type Laves phase and BCC solid solution have been investigated as the next generation hydrogen absorbing alloys with high capacity. We have proposed a new concept of alloy design named 'Laves-phase related BCC solid solution' in the previous work. The observations of microstructure show that Zr0.5Ti0.5VMn consisted of three phases; matrix C14, gray colony BCC and black particle Zr in the previous report. In this work we investigated each phase in detail by the combination of transmission electron microscopy and X-ray Rietveld analysis. The composition of the matrix Laves phase is found to be Zr0.6Ti0.4V1.1Mn0.9 by TEM-EDX. The bright field image of this region is homogeneous and the electron diffraction pattern shows only the C14 structure. We consider that this phase is the Laves phase in which the A site is occupied by Zr and Ti and the B site is occupied by Mn and V. This atomic ratio of matrix is a stable composition of the phase which is contained in Zr-Ti-Mn-V alloys and is made by arc melt casting process. The gray colony BCC phase in Zr0.5Ti0.5MnV decomposes into two nano scale phases that are Mn solute Ti-rich and V-rich phases. The lattice strain of two coherent phases show the satellite spots in electron diffraction and asymmetric peak broadening in X-ray diffraction patterns. Black particle Zr phase is found to be α-ZrO2 by analysis of the electron diffraction. This oxide particle consists of two regions which have the same zone axis.

Original languageEnglish
Pages (from-to)456-462
Number of pages7
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume59
Issue number4
DOIs
Publication statusPublished - Jan 1 1995

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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