Effects of reinforcement morphology on the fatigue and fracture behavior of MoSi2/Nb composites

Abstract The results of a systematic study of the effects of reinforcement morphology on the fatigue and fracture behavior of MoSi 2 /Nb composites are discussed. These include experimental and analytical results obtained from studies of crack growth and crack-tip shielding mechanisms in composites reinforced with Nb particles, fibers and laminae. The crack-tip shielding contributions from crack bridging and crack-tip blunting in fiber-reinforced and laminated composites are analyzed using micromechanics models. Similarly, the toughening contributions from deflection by continuous tilting and twisting of cracks around the layered interfaces in particulate-reinforced composites are also assessed using fracture mechanics models. Linear superposition concepts are then used to obtain predictions of the overall toughening due to the different crack-tip shielding mechanisms. The paper highlights the need to control reinforcement morphology in the design of composites with improved fatigue and fracture resistance.