Untitled

Fabrication of ultrafine and nanocrystalline WC–Co mixtures by planetary milling and subsequent consolidations

“…25 The reason for milling the powder mixture instead of the elements separately is two-fold: a reduction in the Co crystallite size is promoted in a first instance and second there is a homogeneous distribution of the cobalt around the particles in such a way that sintering behaviour is improved. 26 Milling have been carried out in a planetary ball mill from Retsch, using a WC container 500 cm 3 in volume with 10 mm in diameter WC balls. The ball powder ratio was 10 : 1 in any case.…”

“…The properties of WC-Co cermets mainly depend on composition, microstructure and carbide purity. 2,3 In general, reducing WC grain size improves mechanical properties, increasing hardness, wear behaviour and transverse rupture strength without compromising toughness. 4,5 Traditionally WC-Co cermets have been produced by sintering of micrometric powders (1-4 mm).…”

Cr-rich layer at the WC/Co interface in Cr-doped WC–Co cermets: segregation or metastable carbide?

“…In the undoped WC-Co materials, the WC/Co interface features and growth process depend on the C potential [6,7]. Recent ab initio calculations [33] relate the C effect to the atomic structure of the WC/Co interfaces and evaluate interface energies that depend on the C potential for the two types of WC prismatic planes.…”

“…Cr, added as Cr 3 C 2, is one of the elements that limit grain growth during the sintering process but also slower densification [5]. The Cr effect is related to the C potential in the alloy: in C-rich alloys, Cr is less efficient than in W-rich alloys and abnormal growth occurs [6,7]. To understand the role of Cr in the growth inhibition, its distribution in the alloy was investigated by different techniques.…”

Computer simulating the diffusion behavior of V and W in Co binder layer of WC–Co cemented carbide

“…It is well known that the WC grain growth is largely affected by VC addition, say, the diffusion of WC into Co binder phase is controlled by VC content. With some similarities, VC also has to be dissolved into binder phase, then precipitated at the grain boundary of WC/Co [3,6]. Therefore the whole process can be considered as a diffusion process in a W-C-Co-V system.…”