An 8‐wt%‐scandia silicon nitride with an elongated grain structure was fabricated. The material exhibited high fracture toughness (∼ 7 MPa · m1/2) and a risingR‐curve as measured by the indentation strength technique. The “toughening” exponentmwas found to bem∼ 0.1. The high fracture toughness andR‐curve behavior was attributed mainly to bridging of the crack faces by the elongated grains. The crack closure (bridging) stress distribution in the wake region of the crack tip was estimated as afunction of crack size from theR‐curve data, with an arbitrarily assumed dis