Coarsening Kinetics of gamma-prime Precipitates in the Commercial Nickel Base Superalloy Rene88DT (PREPRINT)
Journal article preprint
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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Rene88DT samples were subjected to different cooling rates after a supersolvus treatment, and aged for varying periods of time from 25 to 200 hours at 760 degrees C. Secondary and tertiary gamma-prime precipitate sizes were measured after each heat treatment condition through scanning electron microscopy SEM and energy filtered transmission electron microscopy EFTEM. Coarsening rate constants were calculated and reported from the measured values of precipitate sizes. When describing the change in radius r as a function of time t, good fits between the experimental results and analysis resulted from the use of both types of functional relationships, rexp 3 vs. t and rexp 2 vs. t. The experimental rate constants derived from this analysis were compared with theoretical values deduced from two different models - volume diffusion and interface-controlled diffusion. The mechanism for gamma-prime coarsening has been rationalized based upon the comparison between the analytically derived and experimentally observed values, of these rate constants.
- Physical Chemistry
- Properties of Metals and Alloys
- Test Facilities, Equipment and Methods