Controlled Development and Prediction of Zero-flux Planes, Diffusion Paths and Diffusion Structures in Multicomponent and Multiphase Systems

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This grant explores the phenomenon of isothermal diffusion at 775oC in alpha (a, fcc) and beta (b, bcc) single phase and multiphase alloys in the Cu-Ni-Zn system. A major objective is to reduce interdiffusion of a component through development of a series of zero-flux planes (ZFP) adjacently spaced within the diffusion zone. The study also investigates intrinsic and interdiffusion, as well as development of zero-flux planes, diffusion paths and diffusion structures, in diffusion couples characterized by controlled thermodynamic forces for two of the components. Other goal of the proposed investigations is to develop a user-friendly, multicomponent diffusion code equipped with a library of diffusion data for several multicomponent systems, and capable of analysis and prediction of diffusion paths and diffusion structures in multicomponent assemblies.%%%The experimental portions involve assembling infinite and finite diffusion couples with a and b Cu-Ni-Zn alloys having compositions on an isoactivity line for Ni. These couple pairs are so assembled that the activity differences for Zn and Ni between the terminal alloys are identical in magnitude but different in sign. All couples are analyzed by electron microbrobe techniques. Diffusion structure development in multiphase couples is examined by scanning electron microscopy and transmission electron microscopy. These controlled experiments contribute to better understanding and insights into the intrinsic and interdiffusion phenomena as well as ZFP development in multicomponent systems. The development of the planned diffusion code is expected to serve as a teaching, research and design tool for the analysis and prediction of diffusion paths in multicomponent, multiphase systems and can reach a large audience in the fields of education and industry.***