Dislocation structures in monocrystalline nickel-based superalloys DD8, ZS26 and a directionally solidified cobalt-based superalloy under tensile and fatigue loading are reviewed. An investigation of dislocation structure in DD8 during fatigue loading at 760 degrees C was conducted. Dislocation bands and three-dimensional networks were found in the matrix, Most of the dislocations observed in the gamma'-phase were in the form of superdislocations. The superimposition of the cyclic component to the process of creep resulted in a minor effect on lifetime of single crystal nickel-based superalloy ZS26. Transmission electron microscopy (TEM) reveals different mechanisms of dislocation-gamma' precipitate interaction under various loading conditions. In addition, TEM in-situ investigation of dislocation behaviour at the crack tip in single crystal nickel-based superalloy DD8 was carried out. Dislocation free zone (DFZ) ahead of the crack tip was frequently observed and affected by the nearby gamma/gamma' interfaces. The defects induced by cyclic straining in the single crystal cobalt-based superalloy are mainly characterized by stacking faults and their intersections.
部门归属
acad sinica,inst met res,state key lab fatigue & fracture mat,shenyang 110015,peoples r china.
Z. G. Wang,Y. B. Xu. Dislocation structures in single crystal nickel- and cobalt-based superalloys under tensile and fatigue loading[J]. Defect and Diffusion Forum,1997,152:40925.
APA
Z. G. Wang,&Y. B. Xu.(1997).Dislocation structures in single crystal nickel- and cobalt-based superalloys under tensile and fatigue loading.Defect and Diffusion Forum,152,40925.
MLA
Z. G. Wang,et al."Dislocation structures in single crystal nickel- and cobalt-based superalloys under tensile and fatigue loading".Defect and Diffusion Forum 152(1997):40925.
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