Role of Ru on the Microstructural Evolution During Long-Term Aging of Ni-Based Single Crystal Superalloys

• 来源期刊: 金属学报（英文版）
• 年，卷（期）: 2020,（12）
• 页码范围: 1689-1698
• 页数: 10页
• 语种: 英文

摘要

Two experimental alloys containing different contents of Ru were investigated to study the effect of Ru on the microstruc-tural evolution during long-term thermal exposure.The increase in Ru promoted the formation of cubical,tiny,and even y'phase after full heat treatment.Moreover,the samples after full heat treatment were exposed at 1100℃for different time.Based on the classical model by Lifshitz,Slyozov,and Wagner,the coarsening of γ'phase of the alloy containing 2.5 and 3.5 wt.％Ru during the long-term aging was controlled by the interface reaction and diffusion,respectively.The y/y'lattice misfit was more negative with the increment of Ru addition,which induced the formation of stable rafted γ'phase in the alloy containing 3.5 wt.％Ru at the initiation of long-term aging.Besides,the increase in Ru reduced the diffusion coefficient,which could restrain the γ'phase coarsening.The lower γ/γ'lattice misfit of the alloy containing 2.5 wt.％Ru promoted the interface reaction,which induced the rapid coarsening of y'phase.Therefore,the increase in Ru improved the microstruc-tural stability of the alloys.On the other hand,the raise of Ru induced"reverse partitioning"behavior,which was effective 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 the y matrix.Moreover,the TCP phase was determined as μ phase,which had a high concentration of Co,Re,Mo,and W.A sketch map describing the evolution of the TCP phase was also constructed.