Quantitative analysis for kinetics of reactive diffusion in the Fe–Cr system

Morphology of Compounds Formed by Isothermal Reactive Diffusion between Solid Fe and Liquid Al

“…75) Although the growth rate is not necessarily a simple mathematical function of the interdiffusion coefficient, it is surely a monotonically increasing function of the interdiffusion coefficient. [75][76][77][78][79][80][81][82][83][84] In the early stages, many fine Fe 2 Al 5 grains with random crystallographic orientations are produced at the Fe/Al interface. 72) Of these random grains, those with the c axis nearly perpendicular to the Fe/Al interface preferentially grow along the c axis over long distances without impingement.…”

“…In such a case, the growth of the intermetallic layer is not described by any simple mathematical models reported in previous studies. [75][76][77][78][79][80][81][82][83][84] As a consequence, the rate-controlling process for the growth of the intermetallic layer cannot be estimated from the value of Q k in a straightforward manner.…”

Observation on Isothermal Reactive Diffusion between Solid Ni and Liquid Sn

“…When the interdiffusion coef cient of a compound is very small, the compound cannot grow to detectable thicknesses within realistic annealing times. [24][25][26][27][28][29][30][31][32][33] A diffusion couple technique has been conveniently used by many researchers to determine phase diagrams in multicomponent systems. In this technique, however, all the stable compounds may not be necessarily observed under experimental conditions.…”

“…8, n is smaller than 0.5 at T = 533-623 K. Although the open circles are slightly scattered, there exists no systematic dependence of n on T. When the layer growth is controlled by volume diffusion, n is equal to 0.5. [24][25][26][27][28][29][30][31][32][33] Such a relationship is called the parabolic relationship. If boundary diffusion contributes to the layer growth and grain growth occurs in the intermetallic layer, however, n becomes smaller than 0.5.…”

“…[24][25][26][27][28][29][30][31][32][33] On the basis of the estimation, Q k is compared with the activation enthalpy of the interdiffusion coef cient for each phase. However, n is typically smaller than 0.5 in Figs.…”