- Hurley, G. F. and Labelle, H. E. Jr. and Mitchell, C. R. and Cocks, F. H., ELEVATED TEMPERATURE STRENGTHENING OF MELT-GROWN SAPPHIRE BY ALLOYING.,
Applied Polymer Symposia no. 29
pp. 131 - 149 .
(last updated on 2007/04/10)
Rods and monocrystalline filaments of both chromia doped and pure Al//2O//3 have been produced by edge-defined, film-fed growth (EFG). Rhenium dies and crucibles were found to be effectively resistant to the reaction with chromium containing melts. Al//2O//3 alloy crystals containing up to 1. 5 wt. % Cr//2O//3 have been grown by this process. In the case of pure Al//2O//3, tensile tests made at temperatures between 1650 and 2020 degree C show that a-axis filaments show substantially different mechanical behavior than the c-axis filaments at the highest temperatures. At 2000 degree C both orientations show significant ductility, but the a-axis orientation shows a 30% elongation compared to a more limited 1% for the c-axis orientation. The high temperature strengthening effect of Cr//2O//3 was found to be substantial, provided such doping could be produced without the concomitant production of a voided structure.
CRYSTALS - Growing;CRYSTALLIZATION;ALUMINA;CHROMIUM COMPOUNDS;