MICROSTRUCTURAL EVOLUTION OF THE ETA-PHASE IN THE CU-SN SYSTEM

The formation of eta-phase by a peritectic reaction in the Cu-Sn metal lic system has been cited in the Literature while discussing the solid ification of the high temperature superconductor YBa2Cu3O7 through the peritectic temperature, from Y2BaCuO5 and liquid phases. Similar sche matic phase diagrams and driving forces have been invoked to discuss t he reactions in both cases. Ln this paper, we have studied the microst ructural evolution of the eta-phase from epsilon + liquid in the Cu-Sn system, by observing quenched microstructures at various stages of pr ocessing, when subjected to a thermal schedule similar to the one used for the melt-processing of YBa2Cu3O7 A comprehensive picture of the m echanism by which the eta phase nucleates and grows has evolved.