Coarsening kinetics of γ' precipitates in a Re-containing Ni-based single crystal superalloy during long-term aging  

作　　者：Jiachen Zhang Lin Liu Taiwen Huang Jia Chen Kaili Cao Xinxin Liu Jun Zhang Hengzhi Fu 

机构地区：[1]State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an 710072,China

出　　处：《Journal of Materials Science & Technology》2021年第3期1-10,共10页材料科学技术（英文版）

基　　金：the financial support by the National Natural Science Foundation of China(51631008);the National Key Research and Development Program of China(No.2016YFB0701400);Natural Science Foundation of Shaanxi Province 2020JM-122;the National High Technology Research and Development Program of China(No.2012AA03A511)。

摘　　要：The morphological evolution and coarsening kinetics ofγ'precipitates in a Re-containing Ni-based single crystal superalloy were investigated during isothermal aging at 900,950 and 1000℃.After heat treatment,well-defined cuboidalγ'precipitates with low misfit was obtained within the experimental alloy.Then coarsening rate constants and particle size distribution(PSD)ofγ'phases were calculated and specified based on the measured precipitate sizes for va rying periods of aging times from 100 to 2000 h.After aging for 2000 h,γ'precipitates maintained cubical shape at 900℃,while exhibited sphere at 950 and 1000℃.Coarsening models based on diffusion-controlled process with a functional relationship of r^(3) vs.t(classic Lifshitz-Slyozov-Wagner coarsening model)and interface-controlled model with a function of r^(2) vs.t(trans-interface diffusion-controlled coarsening model)were investigated to fit between the experimental results and theoretical analysis.It was found that Re as the slowest diffusing solute in the alloy constituted the rate-limited step for coarsening based on LSW model,while the process limiting coarsening as governed by an interface diffusion process could possibly be related to the Al diffusion through theγ/γ'interface.The PSDs and coarsening exponent were discussed by comparing the experimental data with predictions of LSW and TIDC models.Finally,coarsening mechanism could be divided into four regimes:(i)coarsening by diffusion-controlled;(ii)coarsening by diffusion and interface cocontrolled;(iii)coarsening by interface-controlled;(iv)coarsening by interface-controlled accompanied withγ'coalescence.

关 键 词：Precipitate coarsening Three-dimensional atom probe(3DAP) Interfacial energy Diffusion Particle size distribution Ni-base single crystal superalloys 

分 类 号：TG132.3[一般工业技术—材料科学与工程]