Effect of tungsten disilicide addition on tungsten boride based composites produced by milling-assisted pressureless sintering

In this study, tungsten boride (WB and W 2 B) based composites with various amounts of  tungsten disilicide (WSi 2 ) addition were fabricated by using a combined method of mechanical  milling (MM), cold isostatic pressing (CIP) and pressureless sintering (PS). MM  was conducted for 4 h in ethanol (wet milling) and Argon atmosphere (dry milling) using a  high-energy ball mill. WSi 2 was used with different amounts (0, 5, 10 and 20 wt.%) in order  to investigate its effect on the resultant products. MM’d powders were compacted using  CIP under a pressure of 450 MPa, and were consecutively sintered at 1600 °C for 2 h and  1770 °C for 2 h under Ar atmosphere. Compositional, physical and microstructural characterizations  of the samples were performed using stereo and optical microscopes, X-ray  diffractometer, TOPAS software, scanning electron microscope coupled with an energy-dispersive  spectrometer, particle size analyzer and gas pycnometer. Sintered products were  also characterized in terms of Archimedes density and Vickers microhardness. Moreover,  the oxidation studies of the samples were performed at 500 and 1000 °C via thermogravimetric  analyzer. The results showed that the highest density, microhardness and oxidation  stability values amongst the fabricated composites were obtained for the dry milled and  sintered WB-20 wt.% WSi 2 sample.