Thermodynamiccalculation,SEM(scanningelectronmicroscopy),TEM(transmissionelectronmicroscopy),XRD(X-raydiffraction),phaseextraction,andchemicalanalysiswereemployedtostudythephasestabilityandphaseprecipitationinanewNi-Cr-Cobasesuperalloyheat-treatedat704and760℃foralongtime.Theresultsshowthattheprecipitatesofthisnewalloyheat-treatedatstandardannealingconditionandheat-treatedat704and760℃foratimeupto2000hareγ′,MC,M23C6,andM6C,andηphaseformsatgrainboundariesandinmatrixofsamplesheat-treatedat760℃aswell.Themassfractionsofγ′(+η),MC,M23C6,andM6Cinallsampleshavenolargechangeswithanincreaseinagingtime,butγ′precipitatesgrowobviously.Theγ′-to-ηtransformationinthesamplesheat-treatedat760℃tookplacewithincreasingagingtime.TheηprecipitatesformaWidmanstattenpattemandtheγ′phaseshaveremeltedpartlyinthesamplesheat-treatedat760℃.Thealloymaintainsabettermicrostructuralstabilityduringprolongedagingat704℃,butaworsemicrostructuralstabilityduringprolongedagingat760℃.
