Creep deformation of WC hardmetals with iron-based binders
File(s)WC-FeCr creep-post review-without markup.pdf (1.54 MB)
Accepted version
Author(s)
Humphry-Baker, Samuel
Vandeperre, Luc
Type
Journal Article
Abstract
Iron is a candidate to replace cobalt in WC hardmetals, due to its lower cost and toxicity. A WC-FeCr
hardmetal was compression tested at 900-1200 °C. Particular attention is paid to the steady-state creep
rates and stress-exponents (n) during isostress treatments. Three regimes of n are observed. Two of
these were previously reported for WC-Co: power law creep (n»3) at stresses below ~100MPa; and
grain boundary sliding (n»1) at higher stresses. A previously unreported regime at very low stresses
(<10MPa), with an exponent of n»2, is also observed. By combining electron microscopy with X-ray
diffraction texture measurements, the low stress regime is attributed to viscous flow of the binder,
which is accommodated by diffusional creep in the WC skeleton. The mechanism may be applicable
to other hardmetals. Compared to analogous WC-Co materials, WC-FeCr shows improved creep
resistance below 1000 °C, which can be explained by its lower self-diffusivity, and a lower solubility
for WC than Co. However, at temperatures corresponding to liquid eutectic formation (~1140 °C), its
creep resistance becomes inferior. These results indicate FeCr may be a suitable replacement for Co
provided the eutectic temperature is not exceeded.
hardmetal was compression tested at 900-1200 °C. Particular attention is paid to the steady-state creep
rates and stress-exponents (n) during isostress treatments. Three regimes of n are observed. Two of
these were previously reported for WC-Co: power law creep (n»3) at stresses below ~100MPa; and
grain boundary sliding (n»1) at higher stresses. A previously unreported regime at very low stresses
(<10MPa), with an exponent of n»2, is also observed. By combining electron microscopy with X-ray
diffraction texture measurements, the low stress regime is attributed to viscous flow of the binder,
which is accommodated by diffusional creep in the WC skeleton. The mechanism may be applicable
to other hardmetals. Compared to analogous WC-Co materials, WC-FeCr shows improved creep
resistance below 1000 °C, which can be explained by its lower self-diffusivity, and a lower solubility
for WC than Co. However, at temperatures corresponding to liquid eutectic formation (~1140 °C), its
creep resistance becomes inferior. These results indicate FeCr may be a suitable replacement for Co
provided the eutectic temperature is not exceeded.
Date Issued
2021-02
Date Acceptance
2020-12-13
Citation
International Journal of Refractory Metals and Hard Materials, 2021, 95, pp.1-8
ISSN
0263-4368
Publisher
Elsevier
Start Page
1
End Page
8
Journal / Book Title
International Journal of Refractory Metals and Hard Materials
Volume
95
Copyright Statement
© Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Identifier
https://www.sciencedirect.com/science/article/pii/S0263436820303383?via%3Dihub
Subjects
0912 Materials Engineering
Materials
Publication Status
Published
Date Publish Online
2020-12-16