Comparative study of Ni-TaC composites via high-energy ball milling activation and spark plasma sintering: Reinforcement, densification, oxidation resistance, and mechanical property

Abstract

In this study, metal matrix composites (MMCs) were produced using nickel (Ni) and tantalum carbide (TaC) powders by high-energy ball milling, and their structural characteristics and microstructural evolution against reinforcement interactions were investigated. The nominal compositions of the Ni-TaC composites were Ni (5, 10, 15, and 20) vol% TaC. The formation of the ductile-brittle (Ni-TaC) components was affected by the continued severe deformation caused by the high-energy ball milling. As a result, a Ni0.92Ta0.08 solid solution was formed, which influenced the lattice distortion and peak shift. The Ni-TaC composites were densely consolidated by spark plasma sintering at 900°C and 60 MPa. The effect of the TaC on the sinterability and mechanical properties of Ni-TaC composites was analyzed based on the shrinkage rate, densification strain, densification strain, uniform distribution of carbide phase in the Ni matrix, grain size, and morphology of crack propagation. Oxidation behavior was analyzed by scanning electron microscopy with energy dispersive X-ray diffraction. The results indicate that the formation of the NiO and TaO2 passive layer for Ni- 15 vol% TaC composites resulted in a 12 µm (thick) oxide layer. This was the thinnest oxide layer on surface at oxidation 1000°C.