Blunting of Tungsten Needles by Surface Diffusion

Publisher Website
Google Scholar
Abstract
Progressive blunting of tungsten needles heated in vacuum is made continuously or intermittently visible by a technique permitting needles to be heated while mounted in a conventional electron microscope. This technique permits the study of surfaces having small radii of curvature where detectable geometric changes due to diffusion occur in conveniently short periods of time. When the needle shape remains similar to its original geometry as its radius increases, a theory of Herring is applicable for distinguishing whether the transport process involved is volume or surface diffusion. Evidence is presented which indicates that surface diffusion predominates in the conditions of these experiments, i.e., for temperatures from 2600°K to 2900°K and radii from 3×10−6 cm to 3×10−5 cm.

This publication has 5 references indexed in Scilit: