英和和英

出典:『Wikipedia』 (2011/04/26 21:24 UTC 版)

英語による解説

引用

The Kirkendall effect is the motion of the boundary layer between two metals that occurs as a consequence of the difference in diffusion rates of the metal atoms. The effect can be observed for example by placing insoluble markers at the interface between a pure metal and an alloy containing that metal, and heating to a temperature where diffusion is possible; the boundary will move relative to the markers. For example, using molybdenum as a marker between copper and brass (a copper-zinc alloy), the region occupied by the brass will expand until it includes the molybdenum. This occurs because zinc diffuses more rapidly than the copper, and thus diffuses out of the alloy down its concentration gradient, thus expanding the area occupied by the brass. Such a process is impossible if diffusion is by the direct exchange of atoms.