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A new method of estimation of diffusion characteristics in ternary systems
Čermák, Jiří ; Rothová, Věra ; Gazda, Aleš
A method was proposed based on an estimation of components of diffusion matrix, Dij, in ternary systems. It makes possible to obtain the concentration dependence of DijŽs in a wide range of concentrations using one diffusion couple only. It is in contrast to the conventional procedure that needs two diffusion couples and provides DijŽs for a single composition related to an intersection of diffusion paths. The method was applied to gammaŽ one-phase interdiffusion in Ni3Al-X (X = Cr, Fe, Nb, Ti) in temperature interval 1173 ů 1533 K.
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Comparison of Al/Ni and Co/Ni Interdiffusion Coefficients in Pseudobinary Sections of Ni3Al-Co alloys
Gazda, Aleš ; Rothová, Věra ; Čermák, Jiří
Interdiffusion in Ni3Al intermetallic alloyed by 0 - 19 at % Co was studied in three pseudo-binary sections: c(Al) = 22, c(Co) = 3.5, and c(Co) = 16 (c in at. %). The experiments were carried out at temperatures between 900 and 1200°C. Since no detectable shift of tungsten inert markers was observed, it was concluded that the intrinsic diffusivities of element pairs with varying concentration (Al/Ni and Co/Ni) in respective pseudo-binary sections are approximately equal one to another. The interdiffusion in pseudo-binary alloys Al/Ni (c(Co) = const.) runs slightly faster than that in pseudo-binary alloys Ni/Co (c(Al) = const.). The relations between the measured interdiffusion coefficients in the Ni3Al-Co ordered gamma prime phase agree well with literature data for the interdiffusion coefficients in both pure gamma prime and Co alloyed gamma prime phases and also for the disordered Al-Ni and Co-Ni solid solutions. They are qualitatively explained by interaction between constituents and/or by their interaction with vacancies.
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Diffusion in Ni3Al-Co intermetallic
Gazda, A. ; Čermák, Jiří
Interdiffusion in Ni3Al intermetallic alloyed by 0-19 at %Co was studied in the temperature range 900-1200 C. An attempt was made, to analyze the interdiffusion coefficient into intrinsic diffusivities of individual components.Since no detecatble shift of inert markers was observed, it was concluded that the intrinsic diffusivities of Ni,Al and Co are aproximately equivalent one to another. The interdiffusion in pseudobinary alloys Al/Ni runs slightly faster than that in pseudobinary alloys Ni/Co. Measurements of 63Ni radiotracer in Ni3Al-Co was measured at 1000-1200 C by residual activity method. Enhanced Ni volume diffusivites observed at 1200C are most likely due to short-circuit diffusion along interphase boundaries in beta + gamma with comma field. The grain boundary diffusion of 63Ni was estimated at 1000C and 1100C. It was in a good agreement with our previous measurements made with pure Ni3Al.
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