| In the papcr,by means of heat trcatmcnt,creep properties measurement and microstructurc observation,an invcstigation has been made into the influcncc of heat treatment regimes on the microstructurc,creep properties,deformation and fracture mechanisms of FGH95 powder nickel-base supcralloy during creep.Results show that after the powder prc-treatcd at 1050℃and 1140℃,and hot isostatic prcssurc at 1150℃,thc alloy obtains the microstructurc in which the thickcrγ′phase is distributed in the boundaries region and the finerγ′phase precipitated with the grain.After using "standard","air cooling" and "oil cooling" heat treatment,the thickerγ′phase is kept in the wider boundary regions,the finerγ' phase is dispersely precipitated with the grains. Compared to "air cooling" heat treatment,after "standard" heat treatment,the thickerγ′phase is precipitated along the boundaries to form the poor region ofγ′phase,which is a main reason of decreasing creep resistance of the alloy.Compared to "oil cooling" heat treatment,after "salt-cooling" heat treatment,the alloy obtains the microstructure in which the finerγ′phase is dispersely distributed within the grain,thereinto,the fact that the finer (Nb,Cr)C and(Cr,W)23C6 carbide particles are discontinuously precipitated on the grain boundaries to improve the combined strength,which may hinder the dislocation movement and enhance the creep resistance of the alloy,therefore,the "salt cooling" treated alloy displays a longer creep lifetimes.In the range of the applied temperatures and stresses,the activation energies and stress exponents of the "oil cooling" and "salt cooling" heat treated alloys during creep are calculated to be Qa = 381.1kJ/mol and Qa = 542.07kJ/mol, respectively.During creep,the deformed features of the "oil cooling" treated alloy is the single and double orientations slipping of dislocations activated within the grains,and the fragmentation of the wider boundaries occurs in the region ofγ′phase.But only dislocation slipping is detected in the grain of the "salt cooling" treated alloy.During creep, the deformed features of the alloy is twinning and dislocation slipping activated within the twins,thereinto,the <110> super-dislocation shearing into theγ′phase may be decomposed to form the configuration of(1/3)<112> super-shockleys dislocation,and the stacking fault.And the fracture features of the alloy is the occurrence of the intergranular and cross-granular fracture,thereinto,the nonsmooth surface appeared in the fracture region is attributed to the finer carbides precipitated along the boundary.
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