高温循环载荷对DZ411合金γ′相演变行为的影响  

Effect of high temperature cyclic loading onγ′phase evolution behavior of DZ411 alloy

作　　者：郑五岳 智一恒 周彤彤 曹铁山[1] 程从前[1] 赵杰[1] ZHENG Wuyue;ZHI Yiheng;ZHOU Tongtong;CAO Tieshan;CHENG Congqian;ZHAO Jie(School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China)

机构地区：[1]大连理工大学材料科学与工程学院,辽宁大连116024

出　　处：《航空材料学报》2025年第2期45-52,共8页Journal of Aeronautical Materials

基　　金：航空发动机及燃气轮机基础科学中心项目(P2021-A-Ⅳ-001-001);船用燃气轮机基础研究项目(MGT2023001);国家自然科学基金项目(51901035)。

摘　　要：为了模拟研究循环载荷对DZ411定向凝固高温合金中强化相(γ′相)演变行为的影响,开展950℃下的循环载荷(平均应力/应力幅值为200 MPa/130 MPa和150 MPa/130 MPa)和恒载荷(200 MPa)等断裂实验研究,并采用光学显微镜和扫描电子显微镜研究不同载荷对以γ′相为代表的合金微观组织的影响。研究表明:两种实验方式对合金枝晶干结构影响较小,但对枝晶间孔洞的数量及尺寸产生显著影响,恒载荷条件下试样中孔洞数量多于循环载荷条件。随着载荷条件的引入,γ′相的形态由无载荷条件下的球化状态转变为筏化结构,其中循环载荷较恒载荷进一步促进了γ′相沿垂直于应力方向发生定向粗化生长,形成尺寸更大、形态更为细长的N型筏化片层结构。模拟断裂实验研究表明,鉴于涡轮机叶片工作时近似于循环的不稳定载荷环境,该条件下γ′相的定向长大加剧了局部应力集中效应,从而导致DZ411合金高温强度和抗疲劳性能的降低,进而增加合金部件发生断裂失效的风险。Optical microscopy(OM)and scanning electron microscopy(SEM)methods are employed to investigate the effect of various load conditions—including a constant load of 200 MPa,an average stress of 200 MPa with a stress amplitude of 130 MPa,and an average stress of 150 MPa with a stress amplitude of 130 MPa—on the microstructural evolution of DZ411 alloy.The experimental findings reveal that the dendrite structure remains relatively unchanged under high temperatures and stress conditions.When compared to a constant load,DZ411 alloy subjected to cyclic loading exhibits a reduced number of interdendritic pores,which are also smaller in size.In the absence of loading,theγ′phase undergoes rafting to form a sheet-like structure.Notably,cyclic loading exhibits a more pronounced promotion effect on the rafting growth process of theγ′phase than directional constant loading.Additionally,cyclic loading facilitates the merging and growth of smallγ′phase particles,leading to the formation of longer sheet structures as moreγ′phases become interconnected.Furthermore,under cyclic loading,the size and morphological differences amongγ′phase particles become more pronounced.

关 键 词：DZ411定向凝固高温合金 循环加载 γ′相 断裂 

分 类 号：V252.2[一般工业技术—材料科学与工程] TG146.15[航空宇航科学与技术—航空宇航制造工程]