Effect of spark plasma sintering on microstructure and mechanical properties of AA7075/B4C/ZrC hybrid nanocomposite fabricated by powder metallurgy techniques

Abstract

In the present work, AA7075/B4C/ZrC hybrid nanocomposite has been fabricated by spark plasma sintering (SPS) process at a temperature of 500 °C with a heating rate of 50 °C/min for a period of 5 min. Microstructures and crystal phase structures have been investigated by scanning electron microscopy and X-ray diffraction techniques, respectively. It is observed from the results that the strong and clean interfaces along with uniform distribution of reinforcement particles are present in the SPS-synthesized composites, while the conventionally sintered composites possessed microporous structures. Mechanical properties of the SPS composite are found to be superior as compared to the conventional-sintered composites, where the high tensile and compression strengths of 605 and 712 MPa, respectively, are noted for SPS composite, while it is 502 and 598 MPa, respectively for the conventional-sintered composites. These observed enhanced properties could be attributed to the unique features of the SPS process, such as limited grain growth, clean interface bond formed via the breakage of oxide layers on particle surfaces due to spark discharges, and enhanced diffusion phenomenon that made the interfaces of the composite to be stronger.