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John E. MorralProfessorPh. D., Massachusetts Institute of Technology, 1969 Tel. (614) 292-6255 Office: 292 Watts Hall
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John Morral received B. Met. E and M.S. degrees in 1964 and 1965 from The Ohio State University and a Ph.D. in 1969 from M.I.T. After three years at the University of Illinois, he moved to the University of Connecticut where, in 2003, he completed a five year term as Department Head of their Metallurgy and Materials Engineering Department.
For the past thirty years he has taught courses on physical metallurgy, thermodynamics, diffusion, and phase diagrams. His major research interest is diffusional kinetics with applications to high temperature coatings, gas-solid reactions and the heat treatment of alloys.
He is chair of the ASM Heat Treating Society Research and Development Committee and helped draft their 1999 R&D Plan. In addition he is active in the Center for Heat Treating Excellence and is Deputy Editor of the Journal of Phase Equilibria and Diffusion. He is a former Chair of the ASM Alloy Phase Diagram, Atomic Transport, and the Thermodynamics and Phase Equilibria Committees. With these committees he has helped organize a dozen national and international conferences including two International Conferences for ASM on Heat Treating.
Research Interests
Over the past decade, both fundamental theory and theory-based models that relate to multicomponent, multiphase diffusion have been developed by the study of diffusion couples. One result of the program was a series of linear equations that had a number of applications: for example, to measure ternary and higher order diffusivities, to predict the shape of concentration profiles, to predict the formation of "zero-flux planes", and to eliminate Kirkendall porosity. In addition new concepts were developed including methods of categorizing concentration profiles, as well as diffusion paths and boundaries between interdiffusion layers.
The program yielded a number of unexpected results. For example microstructures were predicted by computer modeling that had never been reported before. An example is given in Fig. 1 of a diffusion path predicted by DICTRA, a finite difference program. The path indicates a layered microstructure that can be described by the notation 
, in which Greek symbols gave the phases in a layer, while carets (> or <) indicate the relative location of layers and movement direction of boundaries between the layers. As shown in Fig. 2, experimental studies of a similar diffusion couple confirmed the existence of this type of diffusion path and microstructure. A micrograph of the corresponding microstructure is shown in Fig. 3.
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| Fig.1. DICTRA simulation of the diffusion path in a Ni-Cr-Al couple. | Fig.2. Measured diffusion path for a diffusion couple similar to Fig. 1. |
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| Fig.3. Interdiffusion microstucture of the Ni-Cr-Al diffusion couple described in Fig. 2. The dark areas in the gamma layer are Kirkendall porosity. | |
Principles developed during this study of diffusion couples are now being applied to a number of different topics. Example topics are the theory of gas-solid reactions (especially regarding internal oxidation), the interdiffusion of high temperature MCrAlY bond coatings with superalloys, the measurement of diffusivities, and the solutionizing of aluminum castings. Also in work with Professor Yunzhi Wang, we are continuing the study of diffusion couples with phase field modeling.
