Interface integrity based on the control of strain-induced anisotropic diffusion

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The degradation mechanism of Ni-base superalloy under an uni-axial strain at high temperature was analyzed by molecular dynamics (MD)analysis. The strain-induced anisotropic diffusion of Al atoms perpendicular to the interface between finely dispersed .' (Ni3Al)phase and . phase (Ni matrix)was observed clearly in a Ni(001)/Ni3Al(001)interface structure. It was found that Al, Co, Cu, W, and Ti atoms accelerated the rafting. On the other hand, Ta, Pd, Zr, Mo, and Mg atoms were found to suppress the rafting. The estimated results were validated by experiments using thin-film stacked structures. The 0. 2%tensile strain was applied parallel to the interface during the annealing of the stacked structure by using a four-point bending method. It was confirmed that the diffusion of atoms perpendicular to the interface was accelerated drastically. It was also confirmed that titanium and tungsten atoms which are already doped in the alloy accelerated this phenomenon seriously. On the other hand, the addition of palladium and tantalum was found to be effective for suppressing the diffusion of Al atoms around the interface. Therefore, the application of MD analysis to the design of a novel heat resistant material is very effective for improving the efficiency of energy power plants for next generation.