SOLID-LIQUID REACTION IN THE SI3N4-ALN-Y2O3 SYSTEM UNDER 1 MPA OF NITROGEN

The melting behaviors of selected compositions in the Si3N4-AlN-Y2O3 s ystem were determined under 1 MPa of nitrogen. The phase diagrams of t he ternary and their binary systems are presented. The lowest melting composition of the ternary system contains 15 mol% Si3N4, 25 mol% AlN, and 60 mol% Y2O3 and has a melting temperature of 1650 degrees C. The binary eutectic compositions and temperatures are 15 mol% Si3N4 and 8 5 mol% Y2O3 at 1720 degrees C, and 20 mol% AlN and 80 mol% Y2O3 at 173 0 degrees C.