FLOW AND FRACTURE OF HOT-PRESSED POLYCRYSTALLINE SPINEL AT ELEVATED TEMPERATURES
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1965
- Accession Number
- AD0474198
Entities
People
- Dong M. Choi
- Hayne Palmour Iii
Organizations
- North Carolina State University