·832. 工程科学学报，第40卷，第7期 个NbC相团簇剧烈氧化膨胀，从内部萌生了一条微 subjected to different thermomechanical treatments.Mater Sci Eng 裂纹，并且沿主裂纹方向扩展了一段距离.这说明 A.2017.691:195 试样表面的NbC相氧化导致剧烈膨胀会成为潜在 [7]Valle L C M,Araujo L S,Gabriel B,et al.The effect of phase on the mechanical properties of an Inconel 718 superalloy. 的裂纹源，不利于材料在高温下的稳定服役 Mater Eng Perform,2013,22(5):1512 研究δ相对二次裂纹扩展的影响以及表面晶界 [8]Tarzimoghadam Z,Rohwerder M,Merzlikin S V,et al.Multi- 氧化损伤区，不仅有助于了解GH4169合金在高温 scale and partially resolved hydrogen mapping in a Ni-Nb model 下的裂纹扩展行为及损伤机制，而且对实际生产具 alloy reveals the role of the 8 phase in hydrogen embrittlement of 有一定的指导意义.通过研究δ相对二次裂纹扩展 alloy 718.Acta Mater,2016,109:69 行为的影响，能够有针对性地调整热加工和热处理 [9]Jiang R,Bull D J,Proprentner D,et al.Effects of oxygen-related damage on dwell-fatigue crack propagation in a P/M Ni-based su- 工艺，使得合金中析出具有合适的形貌和体积分数 peralloy:from 2D to 3D assessment.Int J Fatigue,2017,99: 的8相，从而提高合金在服役环境下的裂纹扩展抗 175 力.对表面晶界氧化损伤区的研究意味着在服役条 [10]Cruchley S,Li H Y,Evans H E,et al.The role of oxidation 件下不仅裂纹本身会对构件构成威胁，而且对于零 damage in fatigue crack initiation of an advanced Ni-based super- 件外表面的损伤也必须考虑在其中. alloy.Int J Fatigue,2015,81:265 [11]Osinkolu G A,Onofrio G.Marchionni M.Fatigue crack growth 3结论 in polycrystalline IN718 superalloy.Mater Sci Eng A,2003,356 (1-2):425 (1)在650℃、初始△K=30MPa·m2和R= [12]Smith HH,Michel D J.Effect of environment on fatigue crack 0.05的试验条件下，标准热处理态GH4169合金的 propagation behavior of alloy 718 at elevated temperatures.Metall Trans A,1986,17:370 疲劳主裂纹以沿品方式萌生并继续扩展.之后沿品 [13]Evans H E,Li H Y,Bowen P.A mechanism for stress-aided 二次裂纹出现，并且数量和长度沿主裂纹扩展方向 grain boundary oxidation ahead of cracks.Scripta Mater,2013, 逐渐增大.进入快速扩展阶段后，断口呈现韧窝组 69(2):179 织形貌 [14]Pfaendtner JA,MeMahon C J.Oxygen-induced intergranular (2)在裂纹扩展过程中8-y界面发生氧化并开 cracking of a Ni-base alloy at elevated temperatures-an example of dynamic embrittlement.Acta Mater,2001,49(16):3369 裂，使得沿品二次裂纹在δ相处沿δ-y界面扩展， [15] Chen Y Q,Pan S P,Zhou M Z,et al.Effects of inclusions, 从而导致二次裂纹的扩展路径产生偏折.因此δ相 grain boundaries and grain orientations on the fatigue crack initia- 起到阻碍沿品二次裂纹扩展的作用. tion and propagation behavior of 2524-T3 Al alloy.Mater Sci (3)在试样外表面的主裂纹周围出现品界氧化 EngA,2013,580:150 损伤区，其分布沿主裂纹扩展方向大致呈V字形， [16]Foroozmehr F,Verreman Y,Chen JQ,et al.Effect of inclusions 而且其尺寸及品界开裂程度沿主裂纹扩展方向逐渐 on fracture behavior of cast and wrought 13%Cr-4%Ni martensi- tic stainless steels.Eng Fract Mech,2017,175:262 增大. [17]An J L,Wang L,Liu Y,et al.The role of 8 phase for fatigue crack propagation behavior in a Ni base superalloy at room tem- 参考文献 perature.Mater Sci Eng A,2017,684:312 [1]Pollock T M.Alloy design for aircraft engines.Nat Mater,2016, [18] Saarimaki J.Colliander M H.Moverare JJ.Anisotropy effects 15:809 during dwell-fatigue caused by 8-phase orientation in forged In- [2]Xu J H,Huang Z W,Jiang L.Effect of heat treatment on low cy- conel 718.Mater Sci Eng A,2017,692:174 cle fatigue of IN718 superalloy at the elevated temperatures.Mater [19]Krupp U.Kane W M,Laird C,et al.Brittle intergranular frac- Sei Eng A,2017,690:137 ture of a Ni-base superalloy at high temperatures by dynamic em- [3] Nemeth AA N,Crudden D J,Armstrong D E J,et al.Environ- brittlement.Mater Sci Eng A,2004,387-389:409 mentally-assisted grain boundary attack as a mechanism of embrit- [20]Boyd-Lee A D.Fatigue crack growth resistant microstructures in tlement in a nickel-based superalloy.Acta Mater,2017,126:361 polycrystalline Ni-base superalloys for aeroengines.Int Fa- [4]Jiang R,Reed P A S.Critical assessment 21:oxygen-assisted fa- tigue,1999,21(4):393 tigue crack propagation in turbine dise superalloys.Mater Sci [21]Jiang R,Everitt S,Lewandowski M,et al.Grain size effects in a Technol,2016,32(5):401 Ni-based turbine disc alloy in the time and cycle dependent crack [5]Anderson M,Thielin A L,Bridier F,et al.8 phase precipitation growth regimes.Int J Fatigue,2014,62:217 in Inconel 718 and associated mechanical properties.Mater Sci [22]Connolley T,Reed P A S,Starink M J.Short crack initiation EngA,2017,679:48 and growth at 600 C in notched specimens of Inconel718.Mater [6]Silva C.Song M,Leonard K,et al.Characterization of alloy 718 Sei Eng A,2003,340(1-2):139工程科学学报,第 40 卷,第 7 期 个 NbC 相团簇剧烈氧化膨胀,从内部萌生了一条微 裂纹,并且沿主裂纹方向扩展了一段距离. 这说明 试样表面的 NbC 相氧化导致剧烈膨胀会成为潜在 的裂纹源,不利于材料在高温下的稳定服役. 研究 啄 相对二次裂纹扩展的影响以及表面晶界 氧化损伤区,不仅有助于了解 GH4169 合金在高温 下的裂纹扩展行为及损伤机制,而且对实际生产具 有一定的指导意义. 通过研究 啄 相对二次裂纹扩展 行为的影响,能够有针对性地调整热加工和热处理 工艺,使得合金中析出具有合适的形貌和体积分数 的 啄 相,从而提高合金在服役环境下的裂纹扩展抗 力. 对表面晶界氧化损伤区的研究意味着在服役条 件下不仅裂纹本身会对构件构成威胁,而且对于零 件外表面的损伤也必须考虑在其中. 3 结论 (1)在 650 益 、初始 驻K = 30 MPa·m 1 / 2 和 R = 0郾 05 的试验条件下,标准热处理态 GH4169 合金的 疲劳主裂纹以沿晶方式萌生并继续扩展. 之后沿晶 二次裂纹出现,并且数量和长度沿主裂纹扩展方向 逐渐增大. 进入快速扩展阶段后,断口呈现韧窝组 织形貌. (2)在裂纹扩展过程中 啄鄄鄄酌 界面发生氧化并开 裂,使得沿晶二次裂纹在 啄 相处沿 啄鄄鄄 酌 界面扩展, 从而导致二次裂纹的扩展路径产生偏折. 因此 啄 相 起到阻碍沿晶二次裂纹扩展的作用. (3)在试样外表面的主裂纹周围出现晶界氧化 损伤区,其分布沿主裂纹扩展方向大致呈 V 字形, 而且其尺寸及晶界开裂程度沿主裂纹扩展方向逐渐 增大. 参 考 文 献 [1] Pollock T M. Alloy design for aircraft engines. Nat Mater, 2016, 15: 809 [2] Xu J H, Huang Z W, Jiang L. Effect of heat treatment on low cy鄄 cle fatigue of IN718 superalloy at the elevated temperatures. Mater Sci Eng A, 2017, 690: 137 [3] Nemeth A A N, Crudden D J, Armstrong D E J, et al. Environ鄄 mentally鄄assisted grain boundary attack as a mechanism of embrit鄄 tlement in a nickel鄄based superalloy. Acta Mater, 2017, 126: 361 [4] Jiang R, Reed P A S. Critical assessment 21: oxygen鄄assisted fa鄄 tigue crack propagation in turbine disc superalloys. Mater Sci Technol, 2016, 32(5): 401 [5] Anderson M, Thielin A L, Bridier F, et al. 啄 phase precipitation in Inconel 718 and associated mechanical properties. Mater Sci Eng A, 2017, 679: 48 [6] Silva C, Song M, Leonard K, et al. Characterization of alloy 718 subjected to different thermomechanical treatments. Mater Sci Eng A, 2017, 691: 195 [7] Valle L C M, Araujo L S, Gabriel S B, et al. The effect of 啄 phase on the mechanical properties of an Inconel 718 superalloy. J Mater Eng Perform, 2013, 22(5): 1512 [8] Tarzimoghadam Z, Rohwerder M, Merzlikin S V, et al. Multi鄄 scale and partially resolved hydrogen mapping in a Ni鄄鄄 Nb model alloy reveals the role of the 啄 phase in hydrogen embrittlement of alloy 718. Acta Mater, 2016, 109: 69 [9] Jiang R, Bull D J, Proprentner D, et al. Effects of oxygen鄄related damage on dwell鄄fatigue crack propagation in a P / M Ni鄄based su鄄 peralloy: from 2D to 3D assessment. Int J Fatigue, 2017, 99: 175 [10] Cruchley S, Li H Y, Evans H E, et al. The role of oxidation damage in fatigue crack initiation of an advanced Ni鄄based super鄄 alloy. Int J Fatigue, 2015, 81: 265 [11] Osinkolu G A, Onofrio G, Marchionni M. Fatigue crack growth in polycrystalline IN718 superalloy. Mater Sci Eng A, 2003, 356 (1鄄2): 425 [12] Smith H H, Michel D J. Effect of environment on fatigue crack propagation behavior of alloy 718 at elevated temperatures. Metall Trans A, 1986, 17: 370 [13] Evans H E, Li H Y, Bowen P. A mechanism for stress鄄aided grain boundary oxidation ahead of cracks. Scripta Mater, 2013, 69(2): 179 [14] Pfaendtner J A, McMahon C J. Oxygen鄄induced intergranular cracking of a Ni鄄base alloy at elevated temperatures鄄an example of dynamic embrittlement. Acta Mater, 2001, 49(16): 3369 [15] Chen Y Q, Pan S P, Zhou M Z, et al. Effects of inclusions, grain boundaries and grain orientations on the fatigue crack initia鄄 tion and propagation behavior of 2524鄄鄄 T3 Al alloy. Mater Sci Eng A, 2013, 580: 150 [16] Foroozmehr F, Verreman Y, Chen J Q, et al. Effect of inclusions on fracture behavior of cast and wrought 13% Cr鄄鄄4% Ni martensi鄄 tic stainless steels. Eng Fract Mech, 2017, 175: 262 [17] An J L, Wang L, Liu Y, et al. The role of 啄 phase for fatigue crack propagation behavior in a Ni base superalloy at room tem鄄 perature. Mater Sci Eng A, 2017, 684: 312 [18] Saarimaki J, Colliander M H, Moverare J J. Anisotropy effects during dwell鄄fatigue caused by 啄鄄phase orientation in forged In鄄 conel 718. Mater Sci Eng A, 2017, 692: 174 [19] Krupp U, Kane W M, Laird C, et al. Brittle intergranular frac鄄 ture of a Ni鄄base superalloy at high temperatures by dynamic em鄄 brittlement. Mater Sci Eng A, 2004, 387鄄389: 409 [20] Boyd鄄Lee A D. Fatigue crack growth resistant microstructures in polycrystalline Ni鄄base superalloys for aeroengines. Int J Fa鄄 tigue, 1999, 21(4): 393 [21] Jiang R, Everitt S, Lewandowski M, et al. Grain size effects in a Ni鄄based turbine disc alloy in the time and cycle dependent crack growth regimes. Int J Fatigue, 2014, 62: 217 [22] Connolley T, Reed P A S, Starink M J. Short crack initiation and growth at 600 益 in notched specimens of Inconel718. Mater Sci Eng A, 2003, 340(1鄄2): 139 ·832·