Plastic Deformation in Magnesium Oxide Crystals Subjected to Rolling-Contact Stresses

Abstract

Magnesium oxide single crystals were subjected to rolling-contact loads, in the range from 130 000-psi to 173 000-psi Hertz stress, by rolling a ⅛-in. ball on a (001) plane in the [010] direction. The resulting plastic deformation indicated that the stress distribution is not very different than that predicted for isotropic, elastic media. Slip occurred predominantly on the glide planes, which coincided with the planes of maximum shear stress. Plastic deformation was caused by the operation of dislocation sources beneath the surface near the region of the calculated maximum shear stress. The depth of penetration and the number of slip lines were greater on those {110}45 planes which intersected the rolling surface parallel rather than normal to the rolling direction.