Becher P.F.Sun E.Y.Plucknett K.P.Alexander K.B.Hsueh C.-H.Lin H.-T.Waters S.B.Westmoreland C.G.Kang E.-S.Hirao K.Brito M.E.CHUN-HWAY HSUEH2019-09-252019-09-25199800027820https://scholars.lib.ntu.edu.tw/handle/123456789/425041https://www.scopus.com/inward/record.uri?eid=2-s2.0-0032207131&doi=10.1111%2fj.1151-2916.1998.tb02702.x&partnerID=40&md5=4aab200698ab5e1ed5892717d8511c6eThe use of self-reinforcement by larger elongated grains in silicon nitride ceramics requires judicious control of the microstructure to achieve high steady-state toughness and high fracture strength. With a distinct bimodal distribution of grain diameters, such as that achieved by the addition of 2% rodlike seeds, the fracture resistance rapidly rises with crack extension to steady-state values of up to 10 MPa¡Pm 1/2 and is accompanied by fracture strengths in excess of 1 GPa When the generation of elongated reinforcing grains is not regulated, a broad grain diameter distribution is typically generated. While some toughening is achieved, both the plateau (steady-state) toughness and the R-curve response suffer, and the fracture strength undergoes a substantial reduction. Unreinforced equiaxed silicon nitride exhibits the least R-curve response with a steady-state toughness of only 3.5 MPa¡Pm 1/2 coupled with a reduced fracture strength.journal article2-s2.0-0032207131https://www2.scopus.com/inward/record.uri?eid=2-s2.0-0032207131&partnerID=40&md5=82b49792985fc1a631bb4672865a7157