Properties of Ni-aluminides-reinforced Ni-matrix laminates synthesized by pulsed-current hot pressing (PCHP)

Ni-aluminides-reinforced Ni-matrix composites were fabricated from 0.05-mm-thick Ni foils and 0.012-mm- and 0.024-mm-thick aluminum foils by pulsed-current hot pressing (PCHP), and the effect of processing conditions on properties of the composites was investigated. The composites were of laminated structure and composed of Ni and reacted layers containing Ni-aluminides. The composition of the reacted layers was dependent on the reaction temperature employed. Results obtained in tensile testing at room temperature revealed that the reaction temperature affects effectively on mechanical properties of the PCHPed composites, including tensile strength, elongation and fracture mode. The tensile strength and elongation of composites fabricated at 1373 K from 0.05-mm-thick Ni and 0.012-mm-thick Al foils were 500 MPa and 3.8%, respectively. Microstructure observations of fractured specimens showed that Ni layers of the composite played a significant role in prohibiting the growth of numerous cracks emanating from Ni-aluminides. In addition, when fabricated at 1373 K, mutual prevention of crack propagation occurred between Ni-rich Al solid solution layers and cellular Ni3Al in the Ni-aluminide.