Effect of NiO Content on Mechanical Properties of Ni-NiO Composites Prepared by Powder Metallurgy.

Abstract

Ni-NiO composites with different NiO contents were fabricated by a conventional PM method. Nickel oxide particles, which were selected as dispersoids, were embedded in nickel matrix. Tensile tests were conducted on the composites containing up to 9 weight percent of NiO at room temperature. Typical tensile properties, such as yield strength, tensile strength and elongation, of the composites were evaluated. Yield stress of the composites monotonically increased with increase of the NiO content. In contrast, both tensile strength and elongation decreased with increasing NiO content. Variations in the tensile strength of the composites were explained on the basis of the nature and amount of dispersoids and their interaction with nickel matrix. The decrease in the tensile strength was related to its density change. In addition, the relationship between tensile strength and NiO content was well described by Eudier's equation. Decreases in both tensile strength and elongation were caused by propagation of grain boundary cracks initiated from decohesion of dispersoid/matrix interface.