Calculation of vacancy wind contributions in ternary diffusion

In the absence of kinetic cross interactions between diffusing components, intrinsic diffusion can be described by a simple atomic mobility model. For systems where the diffusional interactions among components cannot be ignored, the interactions can be related to a vacancy wind effect in which the intrinsic flux of a component is influenced by the net vacancy flux. Atomic mobilities are calculated at selected composition points on the diffusion paths of y-phase U-Pu- Zr diffusion couples investigated at 750 {degrees}C to assess the contribution by the vacancy wind effect to the intrinsic diffusion of the individual components. The results point to the possibility that a large vacancy wind contribution may cause a component to diffuse intrinsically up its own chemical potential gradient

Diffusion in Grain Boundary Triple Junctions, and its Effects on the Behavior of Nanostructured Materials

Final Report describing reserach carried out at Purdue Universit

Zero-flux planes, flux reversals and diffusion paths in ternary and quaternary diffusion

During isothermal multicomponent diffusion, interdiffusion fluxes of individual components can go to zero at zero-flux planes (ZFP) and exhibit flux reversals from one side to the other of such planes. Interdiffusion fluxes as well as the locations and compositions of ZFPs for components are determined directly from the concentration profiles of diffusion couples without the need for prior knowledge of interdiffusion coefficients. The development and identification of ZFPs is reviewed with the aid of single phase and two-phase diffusion couples investigated in the Cu-Ni-Zn system at 775/sup 0/C. ZFP locations in the diffusion zone nearly correspond to sections where the activity of a component is the same as its activity in either of the terminal alloys of a couple. Path slopes at ZFPs are uniquely dictated by the atomic mobility and thermodynamic data for the components. Discontinuous flux reversals for the components can also occur at interfaces in multiphase couples. Identification of ZFPs is also presented for diffusion in the Cu-Ni-Zn-Mn quaternary system. Analytical representation of diffusion paths for both ternary and quaternary diffusion couples is presented with the aid of characteristic path parameters

Dimensional, microstructural and compositional stability of metal fuels

The projects undertaken were to address two areas of concern for metal-fueled fast reactors: metallurgical compatibility of fuel and its fission products with the stainless steel cladding, and effects of porosity development in the fuel on fuel/cladding interactions and on sodium penetration in fuel. The following studies are reported on extensively in appendices: hot isostatic pressing of U-10Zr by coupled boundary diffusion/power law creep cavitation, liquid Na intrusion into porous U-10Zr fuel alloy by differential capillarity, interdiffusion between U-Zr fuel and selected Fe-Ni-Cr alloys, interdiffusion between U-Zr fuel vs selected cladding steels, and interdiffusion of Ce in Fe-base alloys with Ni or Cr

Transport and thermodynamic properties of solids. Final report

During the last year of operation the principal area of research has been ternary diffusion in solid solution alloys. Specific research projects deal with diffusion in the Cu--Ni--Zn and Fe--Ni--Al systems. Research activities in these areas are summarized