Accession Number : AD0435976


Title :   GENERAL RESEARCH: MECHANICAL BEHAVIOR OF SAPPHIRE


Corporate Author : AEROSPACE CORP EL SEGUNDO CA


Personal Author(s) : Conrad, H


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/435976.pdf


Report Date : 23 Mar 1964


Pagination or Media Count : 42


Abstract : The present state of our knowledge on the mechanical behavior of sapphire is reviewed: Sapphire deforms plastically at temperatures above 900 C, the most common mode of deformation being slip on the basal plan in the 1120 direction. However, under certain conditions, slip may occur on prism planes or twinning may occur. A yield point is often observed. This appears to be related to the multiplication of dislocations by a mechaninism which is controlled by the motion of dislocations through the lattice, rather than by the tearing of dislocations from an impurity (or defect) atmosphere. The dynamics of yielding and flow is similar and can be expressed by either of two thermally activated equations. In one, the effect of stress is principally on the pre- exponential frequency factor; in the other, its effect is principally on the activation energy.


Descriptors :   *SAPPHIRE , *DEFORMATION , CRYSTAL STRUCTURE , TENSILE PROPERTIES , STRAIN(MECHANICS) , FRACTURE(MECHANICS) , CRYSTAL DEFECTS , SHEAR STRESSES , PRESSURE , PHOTOGRAPHIC ANALYSIS , PLASTIC PROPERTIES , SYMMETRY(CRYSTALLOGRAPHY) , ETCHED CRYSTALS , TEMPERATURE , MECHANICAL PROPERTIES


Subject Categories : Geology, Geochemistry and Mineralogy


Distribution Statement : APPROVED FOR PUBLIC RELEASE