Diffusion Studies:

1. Analysis of MultiComponent Diffusion in Quaternary Systems and Multilayered Diffusion AssembliesMysore A. Dayananda, Purdue University,DMR 0304777 Fig. 1:Data for Experimental Concentration profiles for a Cu-Ni-Zn-Mn diffusion couple H/A annealed at 775ºC for 2 days. The profiles regenerated by the MultiDiflux program from the calculated interdiffusion coefficients are also shown as solid lines. Diffusion Studies: A new approach based on a transfer matrix method (TMM) has been developed for the generation of error-function solutions for quaternary, solid-solid diffusion couples. The method was tested with one hypothetical couple with known quaternary interdiffusion coefficients and applied to two experimental Cu-Ni-Zn-Mn quaternary couples annealed at 775 oC. A user-friendly computer program called MultiDifluxhas been developed to analyze the multicomponent diffusion couples for the determination of interdiffusion coefficients and the subsequent regeneration of concentration profiles utilizing the TMM techniques. Several ternary and quaternery diffusion couples have been analyzed with the help of this program. An illustration of the regeneration of concentration profiles for a Cu-Ni-Zn-Mn quaternary diffusion couple is presented in Fig. 1. An analysis of multilayered diffusion assemblies (MDA), such as graded structures, is under way for the evolution of concentration profiles with time. An analytical solution has been developed for the prediction of concentration profiles in single phase MDAs assembled with thin alloy-layers sandwiched between two bulk terminal alloys utilizing a constant set of interdiffusion coefficients. These solutions have been applied to predict the concentration profiles and diffusion paths of a ternary MDA with time. An example of such prediction is presented in Fig. 2, where the predicted profilesare shown along with the experimental composition data for a ternary Cu-Ni-Zn multilayered assemblyannealed at 775ºC for 4 days. Fig. 2:Experimental concentration profiles for a Cu-Ni-Zn MDA annealed at 775ºC for 4 days. The solid lines are the profiles predicted by our analytical solutions.

2. Analysis of MultiComponent Diffusion in Quaternary Systems and Multilayered Diffusion AssembliesMysore A. Dayananda, Purdue University,DMR 0304777 Broader Impact: Kevin Day graduated with a Ph.D degree and has taken up a position as a Process Metallurgist at ATI ALLVAC in Monroe, North Carolina. An application of the MultiDifluxprogram to analyze quaternary diffusion couples of Cu-Ni-Zn-Mn alloys was presented in MS & T Conference held at Cincinnati, OH in 2006. Three technical papers dealing with the theoretical and experimental studies in solid-solid diffusion couples and multilayered assemblies (MDAs) have been either published or in print. A paper published in Philosophical Magazine discusses the determination of quaternary interdiffusion coefficients and the assessment of diffusional interactions in the Cu-Ni-Zn-Mn system. A paper in print in the Journal of Phase Equilibria and Diffusion discusses the application of MultiDiflux to a ternary couple in Ni-Al-Ru system investigated by B.Tryon and T. Pollock at the University of Michigan. An analysis of multicomponent, multilayered assemblies is presented in a paper currently in print in the Journal of Applied Physics. Prof. Ram-Mohan of WPI has been an active contributor to this research work as a consultant. Kaustubh Kulkarni, a PhD student presents a poster in the poster competition held by Materials Science Engineering Graduate Student Association at Purdue University.