一种第四代镍基单晶高温合金的同相位热机械疲劳行为及损伤机制  

In-Phase Thermal-Mechanical Fatigue Behavior and Damage Mechanism of a Fourth-Generation Ni-Based Single-Crystal Superalloy

作　　者：谭子昊 李永梅 王新广[1] 赵浩川 谭海兵 王标 李金国[1] 周亦胄[1] 孙晓峰[1] TAN Zihao;LI Yongmei;WANG Xinguang;ZHAO Haochuan;TAN Haibing;WANG Biao;LI Jinguo;ZHOU Yizhou;SUN Xiaofeng(Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China;Institute of Sichuan Gas Turbine Research,Aero Engine Corporation of China,Chengdu 610500,China)

机构地区：[1]中国科学院金属研究所、师昌绪先进材料创新中心,沈阳110016 [2]中国科学技术大学材料科学与工程学院,沈阳110016 [3]中国航发四川燃气涡轮研究院,成都610500

出　　处：《金属学报》2024年第2期154-166,共13页Acta Metallurgica Sinica

基　　金：国家科技重大专项项目No.2017-Ⅵ-0002-0072;国家重点研发计划项目No.2017YFA0700704;中国科学院青年创新促进会项目。

摘　　要：热机械疲劳是单晶高温合金在实际服役过程中的一种重要损伤模式,澄清合金的热机械疲劳行为及损伤机制对于提升单晶高温合金的服役可靠性具有重要意义。本工作以先进航空发动机高压涡轮叶片用第四代单晶高温合金DD91为对象,采用SEM、EBSD、TEM等手段研究了合金在600~1000℃下的同相位热机械疲劳断裂特征及损伤机理。结果表明,随应变幅的升高,合金的疲劳寿命大幅下降,迟滞曲线明显张开,且应力响应行为由高温半周循环软化和低温半周循环硬化转变为以循环稳定为主导的特征。在不同应变幅下疲劳断裂后,合金断口呈韧性断裂特征,随应变幅的升高,韧窝区面积分数不断下降。在低应变幅下,合金主要承受氧化损伤,并伴随一定程度的蠕变损伤,合金的主要变形机制为位错在γ基体中滑移,并以Orowan机制绕过γ’强化相;而在高应变幅下,合金承受严重的塑性变形损伤而氧化损伤程度减轻,此时界面位错能够以生成层错或反相畴界的形式切割γ’相。另外,合金在不同应变幅下循环至断裂后,均未出现再结晶晶粒和变形孪晶。During the service,the turbine blades of aero-engines are subjected to a complex and ever-changing combination of temperature and stress,resulting in severe cyclic temperature/strain damages and thermal-mechanical fatigue(TMF)failures of the alloy.In this work,in-phase(IP)TMF tests under 600-1000oC were conducted on a newly developed fourth-generation single-crystal superalloy.The alloy's fracture characteristics and comprehensive damage mechanisms were examined via SEM,EBSD,and TEM.The results showed that when the strain range increased,the fatigue life of the experimental alloy noticeably decreased,and the hysteresis loop clearly opened.Stress response behaviors shifted from cyclic softening at high temperatures and cyclic hardening at low temperatures into a dominant characteristic of cyclic stabilizing.The fracture surfaces of alloys displayed ductile features after fatigue fracture under various circumstances,and the area fraction of dimples reduced with increasing strain amplitude.When the strain amplitude was low,the alloy was mainly subjected to oxidation damage,accompanied with a certain degree of creep damage.In contrast,the dominant deformation mechanism of the alloy was dislocation slipping inγmatrix and Orowan by-passing throughγ'particles.As the strain amplitude increased to higher levels,the alloy was subjected to severe plastic deformation damage,while the degree of oxidation damage had been alleviated.Under this condition,the interfacial dislocations could shear into theγ'phase with the generated stacking fault or anti-phase boundary.Notably,no recrystallization grains or deformation twins were formed in the DD91 alloy during the IP-TMF experiments at different mechanical strain amplitudes.

关 键 词：第四代单晶高温合金 热机械疲劳 断裂特征 氧化行为 损伤机制 

分 类 号：TG132.32[一般工业技术—材料科学与工程]