The System Si 3 N 4 ‐SiO 2 ‐Y 2 O 3

Subsolidus phase relations were established in the system Si 3 N 4 ‐SiO 2 ‐Y 2 O 3 . Four ternary compounds were confirmed, with compositions of Y 4 Si 2 O 7 N 2 , Y 2 Si 3 O 3 N 4 , YSiO 2 N, and Y 10 (SiO 4 ) 6 N 2 . The eutectic in the triangle Si 3 N 4 ‐Y 2 Si 2 O 7 ‐Y 10 (SiO 4 ) 6 N 2 melts at 1500°C and that in the triangle Si 2 N 2 O‐SiO 2 ‐Y 2 Si 2 O 7 at 1550°C. The eutectic temperature of the Si 3 N 4 ‐Y 2 Si 2 O 7 join was ∼ 1520°C.