STRENGTH AND FRACTURE OF FULLY DENSE POLYCRYSTALLINE MAGNESIUM OXIDE

The fracture of fully dense, polycrystalline MgO with grain sizes 10 to 500μm, has been studied. Specimens had chemically polished, machined or annealed surfaces. Fracture in chemically polished specimens is initiated by plastic flow, whilst that in machined specimens occurs by the extension of the flaws produced by machining. The fracture of annealed specimens is either initiated by plastic flow or occurs by the extension of the surface flaws, depending on the grain size. The implications of these observations to the strengthening of ceramics are considered. © 1969 Taylor & Francis Group, LLC.