Developing high-performance laminated Cu/TiC composites through melt infiltration of Ni-doped freeze-cast preforms

Nacre-inspired laminated composites have been proven to possess a unique combination of strength and toughness. In this study, we fabricated nacre-mimetic Cu/TiC composites via unidirectional freezing of aqueous TiC slurries containing different amounts of NiO additives, followed by ice sublimation, carbothermal reduction of NiO to Ni during sintering and then gas-pressure infiltration of the Cu melt. The introduction of Ni greatly facilitated the densification of ceramic lamellae and enhanced the interfacial bonding between Cu and TiC. The resultant composites displayed outstanding damage tolerance and anisotropic electrical conductivities. Specifically, for an similar to 31 vol% TiC-Cu composite containing 24 wt% Ni in the ceramic lamellae (based on the TiC content), a fracture toughness (K-Jc) of 72.5 +/- 1.0 MPa.m(1/2), work of fracture of 53.4 +/- 3.5 kJ/m(2), bending strength of 725 +/- 11 MPa and longitudinal electrical conductivity of 22.7 MS/m (similar to 60% of the Cu matrix) were achieved, which were approx. 81%, 536%, 122% and 97% higher than those of the Ni-free composite, respectively. Noticeable toughening was demonstrated to be a consequence of multiple cracking, plastic deformation and uncracked-ligament bridging of the metal layers, as well as crack deflection and blunting. On the other hand, significant strengthening resulted from tailoring the microstructures in the ceramic layers and at the Cu/TiC interface as a result of Ni doping. We believe that the facile strategy adopted herein provides an effective way to solve the problems of wetting and bonding related to metal infiltration and can be readily extended to the preparation of other nacre-inspired metal - ceramic composites.