Quantification of nano-scale interface structures to guide mechanistic modelling of WC grain coarsening inhibition in V-doped hard metals
Journal article, 2021

The control of tungsten carbide (WC) grain coarsening using coarsening inhibitors is considered to be one of the most important advancements for hard metals, leading to metal cutting tools with increased performance. Until now, however, the grain coarsening inhibition mechanism for effective inhibitors such as V has been elusive, posing an obstacle to material optimization. This study serves to quantify the presence of nanoscale V-W-C over a wide range of V/Co ratios by small-angle neutron scattering (SANS). The experiments help to delineate how additions of V affect the nanostructure during sintering and result in smaller WC grains. In contrast to the common view that grain coarsening inhibition originates from the presence of stable nanoscale (V,W)Cx complexions formed at the WC/Co interfaces, we show that V segregates at the WC/Co interfaces already upon a minor addition of V and brings significant coarsening inhibition. Increasing additions of V result in the formation of (V,W)Cx complexions; and above 0.76 wt% V addition, where the coverage on WC grains is complete, no further reduction in average grain size is observed. Mechanistic modelling of grain coarsening reveals that grain coarsening inhibition is governed by the reduction of interface mobilities and total driving force for coarsening.

Hard metals

Small-angle neutron scattering (SANS)

Computational thermodynamics

Mechanical properties

Grain refining

Author

Ahmet Bahadir Yildiz

Royal Institute of Technology (KTH)

R. Prasath Babu

Royal Institute of Technology (KTH)

Manon Bonvalet-Rolland

Royal Institute of Technology (KTH)

Sebastian Busch

Helmholtz

V. Ryukhtin

Nuclear Physics Institute

Jonathan Weidow

Chalmers, Physics, Materials Physics

S. Norgren

Sandvik

P. Hedstrom

Royal Institute of Technology (KTH)

Materials and Design

0264-1275 (ISSN) 1873-4197 (eISSN)

Vol. 207 109825

Subject Categories

Ceramics

Materials Chemistry

Metallurgy and Metallic Materials

DOI

10.1016/j.matdes.2021.109825

More information

Latest update

7/5/2021 2