AN INVESTIGATION OF INTERDIFFUSION IN METALLIC SINGLE CRYSTALS.
Final rept. 1 Nov 62-31 Aug 65,
OHIO STATE UNIV RESEARCH FOUNDATION COLUMBUS
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With the objective of studying defect interaction in the diffusion zone of binary couples, three independent investigations were carried on this project. They are 1 determination of the equilibrium vacancy concentrations in gold-silver alloys 2 study of marker movement in gold-silver alloys and 3 transmission electron microscopy study of thin foils prepared from the diffusion zone of gold-silver diffusion couples. Copper-platinum alloys also were to be investigated, but experimental difficulties did not permit the work to get beyond study of the gold-silver alloys. The most important conclusions of the investigation of equilibrium vacancy concentrations in gold-silver alloys are 1 the vacancy concentrations of quenched pure gold determined with the dilatometer at room temperature are in good agreement with the values obtained by investigators using other methods. 2 The high energy of vacancy formation in the alloys is caused by specimen contraction, resulting from the migration of divacancies, which occurred before the measurements with the dilatometer could begin. 3 The small black spots which are observed in thin foils of quenched gold appear to be very small stacking-fault tetrahedra. 4 A reappearance of delta LL contraction was noted at 600 C for the alloys but not for pure gold and this was found to correspond to a much greater density of vacancy precipitates observed in the alloys. Author