Segregation-Assisted Plasticity in Ni-Based Superalloys

[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.

[发布日期] 2018-09-12

[学科分类] 金属与冶金

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