M y research, funded by the DOE research award DEFG02-93ER45495, has been geared towards the understanding of ordering in metglic alloys. My effort has been focused on analyzing the role of the coupling between structural and chemical degrees of freedom and its impact on the formation of ordered structures, and on the effects of geometrical frustration on ordering in simple spin models. Over the course of this project, I have had the support of three graduate students and two postdoctoral

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... ch associates who devoted half of their time to the project. Significant Accomplishments Interplay of chemical and structural correlations in alloys Undefitanding the detailed structure of disordered metallic alloys is crucial to the study of phase stability in alloys. The coupling between atomic displacements and chemical short range order in disordered alloys is far from being well understood. Particularly interesting are alloys in which the constituent atoms have a large size mismatch. In an effort to elucidate the nature of correlations in such an alloy, a joint theoretical and experimental study of the 50-50 Cu-Au alloy was undertaken. Simulations based on an atomistic model derived from the effective medium theory (EMT) of bonding in metallic systems [l] were compared to experimental results[2]. An important advantage of real-space simulations is that they permit a direct examination of the relationship between local chemical environment and atomic displacements. The EMT based simulations showed a strong correlation between nearest-neighbor environment and interatomic distances. These correlations were more complex than that predicted from simple "size-effect" arguments. The simulations correctly reproduced the chemically specific nearest-neighbor distances in random alloys across the entire Cu,Aul-, concentration range. The nontrivial correlations between atomic displacements and chemical environment indicated that atomic displacements play a significant role in the ordering transition in these alloys. Specifically, any theory of ordering in these alloys have to take into account the coupling between the local chemical order and the local bond lengths. Classical density-functional theory applied to ordering in alloys A theory of ordering which takes into account the role of coupling to strain fields has been formulated by extending the ideas of classical density functional theory of liquids. Classical density functional theory (DFT) is an attractive approach to apply because of its success in describing the freezing transition in liquids and the application of a & lattice gas version of DFT to order disorder transitions in alloysI3, 41. One attraction of *this theory is the possibility of using correlation functions obtained from first-principles A -8 3 y a a 1 E 3 J