一种镍钴基合金的γ′相在高温下析出行为的透射电镜研究
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摘要
本文利用透射电镜原位加热技术和元素分析技术相结合的方法,对一种镍钴基高温合金在800℃保温条件下的第二相析出长大行为进行了原位观测。发现不规则的第二相颗粒在γ基体表面析出,该第二相为Cr原子替代占位的γ′-Ni_3Al结构,Cr、Ti元素的表面偏析以及Ni、Co元素向基体内的扩散造成了该第二相富Cr、Ti而贫Ni、Co的元素分布。长大动力学分析表明,该第二相的析出尺寸与保温时间的三次方根呈线性关系,但其尺寸分布与LSW理论存在较大偏差,主要是由第二相析出密度大、颗粒与基体间非共格弹性畸变、以及颗粒之间的"碰撞"异常长大等原因造成的。扩散热力学分析表明,存在一个由表面扩散主导变为体扩散主导的临界温度,在本实验条件下,第二相的析出长大行为由表面扩散主导。
By using in situ TEM heating and chemical analysis technology, we studied the secondary phase precipitation behavior in a Ni-Co based superalloy during aging at 800 ℃. The precipitation of irregular particles on the surface of the γ matrix was observed. The particles have a Cr-site occupancy γ′-Ni_3Al structure.We also found the Cr-/Ti-rich and Ni-/Co-depleted element distribution of γ′ phase, which could result from the segregation of Ti to the surface,and the diffusion of Ni and Co into the matrix.The particle size is linearly related to the cubic root of the aging time, which is consistent to the classic theory of coarsening kinetic. However, the size distribution deviated from the classical LSW theory significantly, which could be caused by the high precipitation density, particle/matrix incoherent elastic energy, and the abnormal "collision" growth of the particles. Diffusion thermodynamic analysis shows that surface diffusion is the dominant diffusion mode under our experimental conditions.
By using in situ TEM heating and chemical analysis technology, we studied the secondary phase precipitation behavior in a Ni-Co based superalloy during aging at 800 ℃. The precipitation of irregular particles on the surface of the γ matrix was observed. The particles have a Cr-site occupancy γ′-Ni_3Al structure.We also found the Cr-/Ti-rich and Ni-/Co-depleted element distribution of γ′ phase, which could result from the segregation of Ti to the surface,and the diffusion of Ni and Co into the matrix.The particle size is linearly related to the cubic root of the aging time, which is consistent to the classic theory of coarsening kinetic. However, the size distribution deviated from the classical LSW theory significantly, which could be caused by the high precipitation density, particle/matrix incoherent elastic energy, and the abnormal "collision" growth of the particles. Diffusion thermodynamic analysis shows that surface diffusion is the dominant diffusion mode under our experimental conditions.
引文
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[4] 丁青青,李吉学,张泽. 镍基单晶高温合金相界与界面位错的相互作用[J].电子显微学报,2017,36(2):91-95.
[5] 李晴,龙海波,向思思,等. 镍基单晶高温合金短时时效过程中取向变化的原位研究[J].电子显微学报,2016,35(2):97-102.
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[13] HWANG J Y,BANERJEE R,TILEY J,et al. Nanoscale characterization of elemental partitioning between gamma and gamma prime phases in René 88 DT nickel-base superalloy [J]. Metallurgical and Materials Transactions A,2009,40(1): 24-35.
[14] XU L, TIAN C G, CUI C Y, et al. Morphology evolution of unstable γ′ in Ni-Co based superalloy [J]. Materials Science and Technology,2014,30 (8): 962-967.
[15] WU Z F, WU R. Research development of secondary phase particle in dual-phase system[J]. Materials Review,2010, 24(8):113-117.
[16] CHAUDHARI M,SINGH A,GOPAL P,et al. Site occupancy of chromium in the γ′ -Ni3Al phase of nickel-based superalloys: a combined 3D atom probe and first-principles study [J]. Philosophical Magazine Letters,2012,92(9): 495-506.
[17] CHAUDHARI M,TILEY J,BANERJEE R,et al. Site preference and interaction energies of Co and Cr in gamma prime Ni3Al: a first-principles study [J]. Modelling and Simulation in Materials Science and Engineering,2013,21(5):055006.
[18] SAITO Y, HARADA H. The Monte Carlo simulation of ordering kinetics in Ni-base superalloys [J]. Materials Science and Engineering: A, 1997, 223(1): 1-9.
[19] MURARKA S P, ANAND M S, AGARWALA R P. Diffusion of chromium in nickel [J]. Journal of Applied Physics, 1964, 35(4): 1339-1341.
[20] POUND B G, BECKER C H. Composition of surface films on nickel base superalloys [J]. Journal of the Electrochemical Society,1991,138(3): 696-700.
[21] GAO Z J,ZHANG G Q,LI Z,et al. Surface segregation and oxidation behavior of superalloy powders fabricated by argon atomization [C]. Materials Science Forum,2013,748:518-525.
[22] PAUL A R, KAIMAL K, NAIK M C, et al. Lattice and grain boundary diffusion of chromium in superalloy Incoloy-800 [J]. Journal of Nuclear Materials,1994,217(1): 75-81.
[23] PAUL A R, NAIK M C, KAIMAL K. Mass transport of chromium and nickel in Monel-400 [J]. Journal of Nuclear Materials, 1975, 58(2): 205-210.
[24] PRUTHI D D, ANAND M S, AGARWALA R P. Diffusion of chromium in Inconel-600 [J]. Journal of Nuclear Materials,1977, 64(1): 206-210. * Corresponding author
[2] 陈国良. 高等学校教学用书高温合金学 [M]. 北京:冶金工业出版社,1988.
[3] 郭建亭. 高温合金材料学 (上) 应用基础理论 [M]. 北京:科学出版社,2008.
[4] 丁青青,李吉学,张泽. 镍基单晶高温合金相界与界面位错的相互作用[J].电子显微学报,2017,36(2):91-95.
[5] 李晴,龙海波,向思思,等. 镍基单晶高温合金短时时效过程中取向变化的原位研究[J].电子显微学报,2016,35(2):97-102.
[6] KRIEGE O H, Baris J M. The chemical partitioning of elements in gamma prime separated from precipitation-hardened, high-temperature nickel-base alloys [J]. ASM (Amer. Soc. Metals),1969,62:195-200.
[7] LIFSHITZ I M, SLYOZOV V V. The kinetics of precipitation from supersaturated solid solutions [J]. Journal of Physics and Chemistry of Solids,1961,19 (1): 35-50.
[8] MITCHELL W I. Age-hardening of high-temperature, nickel-base alloys (Particle size effects in age hardening of high temperature Ni-based alloys) [J]. Zeitschrift Fuer Metallkunde,1966,57:586-589.
[9] Van Der MOLEN E H, OBLAK J M, KRIEGE O H. Control of γ′ particle size and volume fraction in the high temperature superalloy Udimet 700 [J]. Metallurgical Transactions, 1971, 2 (6): 1627-1633.
[10] WAGNER C. Theorie der alterung von niederschlagen durch umlosen (ostwald-reifung) [J]. Elektrochem,1961(65):581.
[11] CUI H B,GUO J J,SU Y Q,et al. Phase field simulation of particle growth and ostwald ripening for cu-pb hypermonotectic alloy [J]. Acta Metallurgica Sinica,2007,43(9):907-912.
[12] BABU S S,MILLER M K,VITEK J M,et al. Characterization of the microstructure evolution in a nickel base superalloy during continuous cooling conditions [J]. Acta Materialia,2001,49 (20): 4149-4160.
[13] HWANG J Y,BANERJEE R,TILEY J,et al. Nanoscale characterization of elemental partitioning between gamma and gamma prime phases in René 88 DT nickel-base superalloy [J]. Metallurgical and Materials Transactions A,2009,40(1): 24-35.
[14] XU L, TIAN C G, CUI C Y, et al. Morphology evolution of unstable γ′ in Ni-Co based superalloy [J]. Materials Science and Technology,2014,30 (8): 962-967.
[15] WU Z F, WU R. Research development of secondary phase particle in dual-phase system[J]. Materials Review,2010, 24(8):113-117.
[16] CHAUDHARI M,SINGH A,GOPAL P,et al. Site occupancy of chromium in the γ′ -Ni3Al phase of nickel-based superalloys: a combined 3D atom probe and first-principles study [J]. Philosophical Magazine Letters,2012,92(9): 495-506.
[17] CHAUDHARI M,TILEY J,BANERJEE R,et al. Site preference and interaction energies of Co and Cr in gamma prime Ni3Al: a first-principles study [J]. Modelling and Simulation in Materials Science and Engineering,2013,21(5):055006.
[18] SAITO Y, HARADA H. The Monte Carlo simulation of ordering kinetics in Ni-base superalloys [J]. Materials Science and Engineering: A, 1997, 223(1): 1-9.
[19] MURARKA S P, ANAND M S, AGARWALA R P. Diffusion of chromium in nickel [J]. Journal of Applied Physics, 1964, 35(4): 1339-1341.
[20] POUND B G, BECKER C H. Composition of surface films on nickel base superalloys [J]. Journal of the Electrochemical Society,1991,138(3): 696-700.
[21] GAO Z J,ZHANG G Q,LI Z,et al. Surface segregation and oxidation behavior of superalloy powders fabricated by argon atomization [C]. Materials Science Forum,2013,748:518-525.
[22] PAUL A R, KAIMAL K, NAIK M C, et al. Lattice and grain boundary diffusion of chromium in superalloy Incoloy-800 [J]. Journal of Nuclear Materials,1994,217(1): 75-81.
[23] PAUL A R, NAIK M C, KAIMAL K. Mass transport of chromium and nickel in Monel-400 [J]. Journal of Nuclear Materials, 1975, 58(2): 205-210.
[24] PRUTHI D D, ANAND M S, AGARWALA R P. Diffusion of chromium in Inconel-600 [J]. Journal of Nuclear Materials,1977, 64(1): 206-210. * Corresponding author