Microstructure and mechanical properties of tungsten matrix composites synergistically reinforced with TiC-ZrC particles prepared by spark plasma sintering

Abstract

In this paper, W-TiC-ZrC composites with extremely high strength were prepared by high-energy ball milling followed by spark plasma sintering. The microstructure morphology and structural evolution of the composites were thoroughly analyzed by SEM, EDS, EBSD, XRD, XPS and TEM, and the mechanical properties of the composites were accurately evaluated by microhardness tests and compression tests at room temperature and high temperatures. The results show that the micromorphology of W-TiC-ZrC composites changes from a spherical shape to an elongated shape with the increase of TiC-ZrC addition. Meanwhile, the grain size decreased from 1.32 μm to 0.32 μm with the increase of the reinforcing phase content, however, the strength has a significant enhancement, and the microhardness and compressive strength of the W-3%TiC-3%ZrC composites are 952.0 HV and 2754.6 MPa, respectively. In addition, the W-3%TiC-3%ZrC composites were also shown to exhibit sufficient thermal stability, with compressive strengths of 2716.2 MPa, 2560.8 MPa, and 2323.8 MPa at 200 °C, 400 °C, and 600 °C, respectively. The extremely high strength of W-matrix composites is due to the formation of various second phases in the composites. The appearance of the second phases plays a role in fine grain strengthening, dispersion strengthening, solid solution strengthening, and thermal mismatch strengthening.