Surface Examination by Reflection Electron Microscopy

In reflection electron microscopy the surface is viewed very obliquely and the surface protuberances are seen in profile. It is shown that the method may be used for the quantitative study of surface finish. The method is particularly suitable for the examination of surfaces on which the irregularities are small and ground, lapped, finely abraded and polished surfaces can conveniently be studied. Micrographs of various metals show that ground surfaces of comparable roughness may have different textures and these differences appear to be related to the mechanical properties of the metals. The range of surface finish which can be examined is illustrated by micrographs of electropolished aluminium which, over large areas, is flat to about 0.1 deg. and on which the highest asperity is 0.4 micro-inch, and of ground hardened tool steel with asperities up to 70 micro-inches high and sloping at 30 deg. to the general surface. The method is suitable for the examination of surface damage by wear processes and the s...