Accession Number : AD0450409

Title :   THE INVESTIGATION OF THE EFFECT OF AN ISOSTRUCTURAL BOUNDARY ON THE PLASTIC FLOW CHARACTERISTICS OF POLYCRYSTALLINE IONIC SOLIDS.

Descriptive Note : Progress rept. no. 2, 16 Oct 63-15 Oct 64,

Corporate Author : STANFORD RESEARCH INST MENLO PARK CA

Personal Author(s) : Gorum, A. E.

Report Date : 15 OCT 1964

Pagination or Media Count : 4

Abstract : This program was concerned with a study of the effects of an isostructural boundary on the mechanical characteristics of magnesium oxide. An earlier investigation, which demonstrated that thin layers of soluble oxides on the surface of MgO could decrease the yield strength and promote ductility, led to consideration of utilizing this phenomenon as a means of promoting ductility in polycrystalline bodies. If successful in MgO, then the techniques could be extendded to other materials such as carbides, nitrides, etc. The feasibility of the mechanism was established in synthetic bicrystals made by placing a soluble oxide (NiO) between two single crystals of MgO and observing the slip distribution, using established etching and polishing pjocedures. It was then decided to proceed to polycrystalline material; liquid-phase sintering and hot pressing were employed to produce a two-phase structure. In every case grain growth promoted the distribution of the second phase, and although a high density ceramic was produced, the desired structure was not obtained. (Author)

Descriptors :   (*CRYSTALS, MAGNESIUM COMPOUNDS), (*SPHERES, MAGNESIUM COMPOUNDS), OXIDES, IONS, SOLIDS, MECHANICAL PROPERTIES, DUCTILITY, PLASTIC PROPERTIES, SURFACE PROPERTIES.

Distribution Statement : APPROVED FOR PUBLIC RELEASE