Chromium segregation at phase boundaries in Cr-doped WC-Co cemented carbides
Artikel i vetenskaplig tidskrift, 2018

Atom probe tomography has shown (Cr,W)C to be present as a thin WC grain surface layer in an as-sintered Cr-doped WC-Co cemented carbide microstructure slowly cooled from the sintering temperature. The Co-rich binder phase contained a segregation of Cr in front of this surface layer. The mixed carbide layer was not observed when the as-sintered material had been heat treated at 1000 °C for 3000 s and then quickly cooled. A reduced amount of segregated Cr was, however, still present in the binder phase in front of the WC grain surface. These observations are supported by predictions from thermodynamic modelling; (Cr,W)C becomes stable at temperatures below 940 °C in the absence of other secondary carbides. The equilibrium segregation of Cr in the binder phase was estimated to 0.8 and 0.4 monolayer in the as-sintered and heat treated materials, respectively. The energy of segregation was calculated to 0.22 eV/Cr atom from the atom probe data. This value would result in a Cr segregation of 0.3 monolayer at the sintering temperature 1410 °C, provided that the energy of segregation in the Co-rich liquid phase sintering medium is the same as in the Co-rich binder phase. This Cr segregation may explain the WC grain growth inhibiting effect of Cr additions to WC-Co cemented carbide materials.

APT

Gibbs interfacial excess of Cr

Thermodynamic modelling

Equilibrium segregation of Cr

Författare

Mohamed Amine Yousfi

Swerea KIMAB

Chalmers, Fysik, Materialens mikrostruktur

S. Norgren

Sandvik

Hans-Olof Andrén

Chalmers, Fysik, Materialens mikrostruktur

Lena Falk

Chalmers, Fysik, Materialens mikrostruktur

Materials Characterization

1044-5803 (ISSN)

Vol. 144 48-56

Inverkan av mellanytekemi och mellanytestruktur på kornmorfolgi och plastisk deformation av hårdmetall

Seco Tools AB, 2014-01-01 -- 2015-12-31.

Sandvik, 2014-01-01 -- 2015-12-31.

Vetenskapsrådet (VR), 2014-01-01 -- 2016-12-31.

Ämneskategorier

Keramteknik

Materialkemi

Metallurgi och metalliska material

DOI

10.1016/j.matchar.2018.06.034

Mer information

Senast uppdaterat

2018-11-05