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      https://www.ias.ac.in/article/fulltext/boms/020/05/0623-0635

    • Keywords

       

      Shock compression; phase transformations; crystallography; stereographic; projection; correspondence matrices; transformation strains

    • Abstract

       

      In 1973, Usikov and Zilbershtein proposed that theα(hcp) →ω (a three atom hexagonal) transformation in Zr and Ti proceeds via theβ(bcc, a high temperature phase) intermediate. Based on this they derived two non-equivalent orientation relationships (OR) betweenα andω phases. Their transmission electron microscopy (TEM) study carried out on these elements, that wereαω-transformed under static high pressure, revealed only one of the two proposed ORs. Various TEM studies done thereafter on these elements and their alloys (ω transformed under static pressures) conform to either one of these ORs. In a recent TEM study by Song and Gray on Zr,ω-transformed under shock compression, a new OR has been observed which according to them is different than those given by UZ and they put forth the directαω transformation mechanism. In the present study, we have generated additional TEM data on shock compressed Zr samples and have reconciled the above conflicting results. We find all our ORs (which contain the OR of SG also) to be described by the OR reported by UZ. The latter OR (i.e. of SG) is shown to be a subset of the former. These observations show that the same type of mechanism of transformation is operative both, under static and shock compression. Mechanism of the transition is discussed in terms of the required strains.

    • Author Affiliations

       

      G Jyoti1 K D Joshi1 Satish C Gupta1 S K Sikka1 G K Dey1 2 S Banerjee1 2

      1. High Pressure Physics Division, Bhabha Atomic Research Centre, Mumbai - 400 085, India
      2. Metallurgy Division, Bhabha Atomic Research Centre, Mumbai - 400 085, India
    • Dates

       
  • Bulletin of Materials Science | News

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