FRACTURE CHARACTERISTICS OF METAL INTERMETALLIC LAMINAR COMPOSITES PRODUCED BY REACTION SINTERING AND HOT-PRESSING/

Metal/intermetallic layered composites were formed by process recently developed in which a self-propagating, high-temperature synthesis rea ction was initiated at the interface between dissimilar metal foils. A fter the reaction, one of the metal foils was entirely consumed, resul ting in a metal/intemetallic laminar composite. This study details the tensile fracture characteristics of these unique composites. Fracture mechanism and failure energy were controlled by varying the intermeta llic-to-metal volume ratio. Failure initiated with the formation of cr acks in the intermetallic layer. For high intermetallic-to-metal ratio s, the intermetallic crack release energy was too great to prevent cra cks from propagating through the metal layer and propagating the crack into the adjacent intermetallic layers, leading to a fast, low energy fracture. For lower intermetallic-to-metal ratios, the metal layers a dsorbed the intermetallic crack release energy and blunted the propaga ting crack. Final failure resulted by ductile fracture of the metal la yer after extensive intermetallic cracking.