53Ni-20Co-15Cr 基耐熱合金におけるγ' 相の成長

概要

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The nucleation and growth behaviors of γ' precipitates in a 53Ni-20Co-15Cr-5Mo-4.9Al-1.3Ti alloy have been investigated mainly by micro-Vickers hardness test, X-ray diffraction analysis and transmission electron microscopy. The obtained results are as follows : (1) The γ' precipitates were observed to be spherical at the early stage of aging time and to be cuboidal at the later stage. (2) The hardness of specimens aged in various conditions closely related to the size and the quantity of γ' precipitates. (3) The γ' precipitation cannot be stopped by water quenching after solution treatment. It is necessary to quench the specimen at the rate of over 10^4 K/s to restrain the precipitation of γ' phase. (4) The growth kinetics of γ' precipitates in the alloy followed the prediction of Lifshitz-Slyozov-Wagner(LSW) theory of volume diffusion controlled growth at all aging temperatures. The activation energy for the growth of γ' precipitates was estimated to be 266kJ/mol which was nearly similar to those of diffusion of solute atoms ; ie. Al, Ti and so on, in Ni and Ni alloys. (5) The actual particle size distribution of γ' precipitates was somewhat different from the distribution predicted by the LSW or Brailsford-Wynblatt encounter modified (BWEM) theory.
社団法人日本鉄鋼協会の論文
1993-01-01