Microstructure and Mechanical Properties of Ni/Intermetallic Laminate Composites Produced by Pulsed Current Hot Pressing (PCHP)

Ni-aluminides reinforced Ni matrix composites were fabricated from 0.05 mm-thick Ni foils with 0.012 mm-thick aluminum foils, using pulsed current hot pressing (PCHP) process, and the effect of holding temperature on the properties of the composites was investigated. The microstructure of the composite was laminated structure composed of Ni and Ni-aluminides. With increasing holding temperature during PCHP, the thickness of Ni-rich Ni solid solution layer increased, while the thickness of Ni matrix layer decreased. Tensile tests at room temperature revealed that the mechanical properties of the composites depended on the holding temperature. The tensile strength and the elongation of the composite fabricated at 1373 K showed 500 MPa and 3.8%, respectively. These mechanical properties of the composite were higher than those by conventional vacuum hot pressing techniques. Microstructural observations of fractured specimens showed that the Ni layers effectively bridged numerous cracks formed in the Ni-aluminides in the composites.