Acta Metallurgica Sinica (English Letters)

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Phase Stability of the Laves Phase Cr2 in a Two-Phase Cr-Cr2Nb Alloy

Kewei LI1), Shuangming LI1),Sixiang ZHAO2), Hong ZHONG1), Yunlong XUE1), Hengzhi FU1)   

  1. 1)State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072,China
    2) Institute of Plasma Physics Chinese Academy of Sciences, Hefei 230031, China
  • Received:2013-03-11 Revised:2013-07-14 Online:2013-12-25 Published:2014-02-28
  • Contact: Shuangming LI
  • Supported by:

    National Natural Science Foundation of China (Nos. 50971101, 51074127 and 51104120).

Abstract:

The phase stability of the Laves phase Cr2Nb in a two-phase Cr-Cr2Nb alloy produced by arc-melting was investigated using X-ray diffraction, transmission electron microscopy and selected area electron diffraction. The experimental results indicated that the as-cast ingot was consisted of C15-Cr2Nb and Cr phases; the intermediate C36 and high-temperature C14 modifications of Cr2Nb, reported in literatures, were not detected in this study. These results, combined with a detailed analysis of the actual solidification conditions, revealed that the C14-Cr2Nb was a metastable rather than a stable high-temperature modification. Moreover, a kind of extremely fine lamellar structure was found to be randomly distributed in the eutectic cells, which may be formed by decomposition of the supersaturated C15-Cr2Nb via a discontinuous precipitation reaction.

Key words: Laves phase, Microstructure, Intermetallics, Phase transformation