minoo karbasi

In this study, WC–20 wt.% equiatomic (Fe,Co) powder mixture was milled in a planetary ball mill. The effects of different milling time (15 min, 5h, 10h, and 25 h) and sintering temperatures on the microstructure and mechanical properties of this equi-Fe substituted cermet were investigated. The structural evolution and the crystallite size changes of the powders during milling were monitored by X-ray diffraction (XRD). Microstructure developments of the samples were examined using scanning electron microscope (SEM). The results showed that the crystalline size of WC and internal strain were 22 nm and about 1.1 % after 25 hours of milling, respectively. The hardness and the relative density of the WC-20wt.% (Fe,Co) composites consolidated by conventional sintering at different temperatures, ranging from 1150 to 1450 ˚C in hundreds, were investigated. The optimized sintering temperature was measured at 1350°C. At a constant sintering temperature, 1350°C, the highest relative density of 98.2% and hardness of 1281 (HV30) were obtained for the milling time of 25h.

The aim of the present work is to study the effects of the nanostructured WC-20 wt. % (Fe,Co) with different ratios of iron to cobalt on the microstructure and hardness of sintered samples. Furthermore, a sample with a cobalt binder under the same condition was produced for the comparison purposes. The nanocomposite development, after different milling times, has been monitored by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A homogenous distribution of nanostructured WC (crystallite size less than 30 nm) in the binder matrix was formed after 25 h milling. The hardness and the relative density of the WC-20wt. % (Fe,Co) composites consolidated by conventional sintering at 1350˚C were investigated. In sintered samples after 25 h milling, tungsten carbide grains have a uniform distribution with a lower grain size. Densification and hardness improved after 25 h milling and reached optimum levels for the 25 h milled powders with equal ratio of iron to cobalt.