Accession Number : AD0474198


Title :   FLOW AND FRACTURE OF HOT-PRESSED POLYCRYSTALLINE SPINEL AT ELEVATED TEMPERATURES


Descriptive Note : Technical rept.


Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF ENGINEERING RESEARCH


Personal Author(s) : Choi, Dong M ; Palmour, Hayne, III


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/474198.pdf


Report Date : Jul 1965


Pagination or Media Count : 96


Abstract : High purity (approximately 99.94%) fine particle size (40 m ) MgAl2O4 spinel prepared by chemical coprecipitation was hot pressed using the rate- controlled method in a graphite die. The average density of three hot-pressed compacts was 99.2% of theoretical and the average grain size was 0.5 micron. Compression specimens cut from these compacts were heat treated at various temperatures and time periods to achieve the desired amount of grain growth. The specimens then were tested in compression in vacuo at prescribed temperatures and strain rates and the amount of flow stress (the dependent variable in this investigation) was measured in each case. Grain size, temperature, and strain rate (the independent variables in this investigation) covered the range 0.5 - 200 microns, 1350 - 1800 C, and 0.05 - 5%/min, respectively. The microstructure of specimens was examined carefully after the test and the findings were related to the work hardening revealed in the stress-strain diagrams and to the failure mechanism of the specimens.


Descriptors :   *CERAMIC MATERIALS , *SPINEL , PARTICLE SIZE , MECHANICAL PROPERTIES , MICROSTRUCTURE , HIGH TEMPERATURE , DEFORMATION , CRYSTALS , FRACTURE(MECHANICS) , HEAT TREATMENT , CRYSTAL DEFECTS , PLASTIC PROPERTIES , DUCTILITY , MAGNESIUM COMPOUNDS , HARDENING , REFRACTORY MATERIALS , GRAIN BOUNDARIES , COMPRESSIVE PROPERTIES , ALUMINATES


Subject Categories : Ceramics, Refractories and Glass
      Crystallography


Distribution Statement : APPROVED FOR PUBLIC RELEASE