摘要
Two experimental alloys containing diff erent contents of Ru were investigated to study the eff ect of Ru on the microstructural evolution during long-term thermal exposure.The increase in Ru promoted the formation of cubical,tiny,and evenγ′phase after full heat treatment.Moreover,the samples after full heat treatment were exposed at 1100℃ for diff erent time.Based on the classical model by Lifshitz,Slyozov,and Wagner,the coarsening ofγ′phase of the alloy containing 2.5 and3.5 wt.%Ru during the long-term aging was controlled by the interface reaction and diff usion,respectively.Theγ/γ′lattice misfi t was more negative with the increment of Ru addition,which induced the formation of stable raftedγ′phase in the alloy containing 3.5 wt.%Ru at the initiation of long-term aging.Besides,the increase in Ru reduced the diff usion coeffi cient,which could restrain theγ′phase coarsening.The lowerγ/γ′lattice misfi t of the alloy containing 2.5 wt.%Ru promoted the interface reaction,which induced the rapid coarsening ofγ′phase.Therefore,the increase in Ru improved the microstructural stability of the alloys.On the other hand,the raise of Ru induced"reverse partitioning"behavior,which was eff ective in suppressing the emergence of the topologically close-packed phase(TCP phase).The TCP phase occasionally occurred in the alloy containing 2.5 wt.%Ru,which was attributed to the high temperature and the supersaturation of theγmatrix.Moreover,the TCP phase was determined asμphase,which had a high concentration of Co,Re,Mo,and W.A sketch map describing the evolution of the TCP phase was also constructed.
基金
financially supported by the National Science and Technology Major Project(No.2017-VI-0002–0072)
the National Key R&D Program of China(No.2017YFA0700704)
the National Natural Science Foundation of China(Nos.51671188,51601192 and 51701210)
the Youth Innovation Promotion Association,Chinese Academy of Sciences and State Key Lab of Advanced Metals and Materials Open Fund(No.2018-Z07)。
