Segregation-Assisted Plasticity in Ni-Based Superalloys

Barba, D ; Smith, T M ; Miao, J ; Mills, M J ; Reed, R C

关键词: CREEP ANALYSIS;    CRYSTALLOGRAPHY;    CRYSTAL DEFECTS;    DIFFUSION;    ELECTRON ENERGY;    HEAT RESISTANT ALLOYS;    MATHEMATICAL MODELS;    NICKEL ALLOYS;    PLASTIC PROPERTIES;    X RAY SOURCES;   

RP-ID  :  GRC-E-DAA-TN57666

学科分类：金属与冶金

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

Correlative high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy are used to study deformation-induced planar faults in the single crystal superalloy MD2 crept at 800°C and 650 MPa. Segregation of Cr and Co at microtwins, APBs, CISFs/SISFs and CESFs/SESFs is confirmed and quantified. The extent of this is found to depend upon the fault type, being most pronounced for the APB. The CESF/SESF is studied in detail due to its role as a precursor of the microtwins causing the majority of plasticity under these conditions. Quantitative modelling is carried out to rationalize the findings; the experimental results are consistent with a greater predicted velocity for the lengthening of the CESF/SESF { compared with the other types of fault { and hence confirm its role in the diffusion-assisted plasticity needed for the microtwinning mechanism to be operative.