Self-healing and mechanical properties of reinforced nickel-dispersed alumina hybrid nanocomposites

Dense specimens of 5 vol% Ni/Al2O3 nanocomposites with fine grain size of Al2O3 and nano-Ni particles were fabricated by the pulsed current sintering technique. Vickers hardness, fracture toughness and bending strength of the nanocomposites were investigated at room temperature. Self-healing performance was evaluated at temperatures ranging 1100 similar to 1300 degrees C for 1 similar to 24 h. Bending tests were conducted on samples before and after heat-treatment in order to clarify the self-healing performance. As a result, fabricated sample achieved 995 MPa in bending strength and 6.1MPam(1/2) in fracture toughness. Introduced cracks on sample surface completely disappeared after heat-treatment at 1100 degrees C for 24 h. However, only 80% of cracks disappeared after heat-treatment at 1200 o C for 1 h in air. Bending strength of samples that were introduced cracks recovered up to the level as high as that of sintered samples after heat-treatment at 1200 degrees C for 6 h in air.