| This study was perfomed as fundamental studies on the solid state sintering. The ordinary process of Rene 95 forming is canning of powders followed by HIPP`ing. In this study, the effects of pre -heat treatment, at 1150℃ for 30min after canning of powders, on the microstructure of the HIPP`ed Rene 95 were studied as compared with the ordinary HIPP`ing. The prior particle boundaries(PPB`s) are well known to impair significantly the mechanical properties at service conditions. The PPB`s are observed after 60 min ordinary HIPP`ing at 1150℃, 100MPa, In case of pre-heat treated powders the PPB`s couldn`t be found after 5 min HIPP`ing. The PPB`s were appeared to be related to the precipitation of γ` phase in Rene 95. The pre-heat treatment of powders also assist the recrystallization during HIPP`ing. The grain size variations during HIPP`ing were caused by nuclation of recrystallization, grain growth and subsequent recrystallization(dynamic recrystallization). The microstructure of 30 min HIPP`ed sample of pre-heat treated powders was comparable with the sample HIPP`ed by ordinary process for 180 min at the same condition. |
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