High‐Temperature Toughness and Tensile Strength of Whisker‐Reinforced Silicon Nitride

The R ‐curve behavior of hot‐pressed silicon nitride reinforced with silicon carbide whiskers is investigated from room temperature to 1300°C using the chevron‐notch bend test. The bridging stress, estimated from increment of fracture resistance in the rising R ‐curve, is discussed in relation to tensile strength measured with various displacement rates at 1300°C. The reinforcing whiskers provide most of the tensile strength in the creep‐deformation range at 1300°C. The whiskers appear to bear a great deal of the applied tensile stress during slow crack growth.