The effect of triangularly waved metal fiber on fracture behavior of brittle matrix composites.

From the point of suppressing the crack growth, an attempt to improve the resistance to fracture of ceramic matrix composites was made on Al2O3 matrix/tungsten fiber composite using triangularly waned fiber for the reinforcement.On the monotonic loading flexure test, large plastic deformation was found with holding the maximum strength of the composite, where clear stepwise change in strength against deflection was observed on the load-deflection curve. These phenomena were seen under the condition that fibers were still unbroken.Superior resistance to ratchetting of the deflection against cyclic loading was found on the cyclic loading flexure test, in comparison with straight fiber reinforced composite.No delamination was observed on the Charpy impact test, where straight fiber reinforced composite exhibited serious delamination over the whole test piece.Microscopic observation on the crack extension path clearly showed that triangularly waved fiber had a peculiar effect on suppressing crack growth by way of the branching or turning of the crack path.Mechanism of the crack growth suppression was discussed from a point of the reduction of stress intensity factor induced by serious turning or branching of the crack path.