Diffusion in Metallen

Formation of boride layers at the Fe–10% Cr alloy–boron interface

“…7): The diffusional growth kinetics of compound layers are usually treated using parabolic equations of the type x 2 = 2k 1 t, where x is the layer thickness, k 1 the layer growth-rate constant and t the time [9,13,14]. For sufficiently thick layers, such equations produce a quite satisfactory fit to the experimental data ( Fig.…”

The mobility of an alkali promoter as probed in situ during a catalytic reaction: Li in the CO oxidation on Pt

“…3 -5 In a simplified way, this kind of redistribution, caused by a gradient of the chemical potential across the surface and kinetically controlled by the varying dopant diffusivity, can be traced back to the spinodal decomposition, which is well known as a three-dimensional (3D) effect and explained in terms of an 'up-hill diffusion'. 6,7 Only a few examples of a '2D projection' of this effect, such as concentration patterns of electropositive adsorbates resulting from the up-hill diffusion in two-dimensional firstorder phase transitions under reaction-free conditions, are described in the literature. 8,9 A simple mathematical model, based on the phenomenological consideration of a strong affinity between potassium and oxygen and accounting for Ł Correspondence to: Y. Suchorski, Chemisches Institut, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, D-39106 Magdeburg, Germany.…”

Interfacial interaction of solid nickel with liquid Pb-free Sn–Bi–In–Zn–Sb soldering alloys

“…Conventionally, the intermetallic-layer growth kinetics are treated with the use of parabolic equations following Fick's laws with the assumption of quasi-stationary concentration distribution of any component within the growing layers [13][14][15][16]. However, if the solubility of a solid metal in a liquid soldering alloy is not zero, as is practically always the case, then the growth rate constant found experimentally proves timedependent.…”