Effect of mechanical activation of WC-based powder on the properties of sintered alloys

OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 23 No. 1 2021 Fig. 6. Lattice parameters and degree of tetragonality for WC phase on the milling time of powder a b Fig. 7. SEM images and grain size distribution: the initial state ( a ); after ball milling for 60 seconds ( b ) Figure 9 shows the dependence of the hardness of sintered materials on the time of mechanical processing of powders, the literature data are also presented here [3]. The hardness of alloys is known depend on a number of parameters: grain size of the carbide phase, binder content, porosity, etc. [5, 26-29]. Therefore, it is dif fi cult to make an unambiguous comparison with the data obtained; obviously, machining initially leads to a decrease in hardness, and then it increases again and at 60...100 s of processing b is close to the sintered material from untreated powder [3]. Apparently, the decrease in hardness in the sample at 10 s of treatment is due to the large grain size (1.2 μ m σ = 0.6 μ m) and signi fi cant porosity (11.6 ± 0.2 %). In a sample sintered from mechanically activated powder for 60 s the increase in hardness is, in contrast, associated with a decrease in both grain size (0.9 σ = 0.5 μ m) and porosity (8.1 ± 0.5 %), however, with more intense mechanical activation hardness decreases slightly against a slight decrease in grain size and increased porosity.