A Mössbauer spectroscopy study of Fe based cemented carbides. (February 2020)

• Record Type: Journal Article
• Authors: Peters, G.; Naidoo, D.; Masenda, H.; Genga, R.M.; Freemantle, C.S.; Cornish, L.A.
• Is Part Of: International journal of refractory metals & hard materials. Volume 87(2020)
• Publication Date: 2020-02
• Subjects: Cemented carbides -- Fe binders -- Hardness -- XRD -- SEM -- Mössbauer spectroscopy; Heat resistant alloys -- Periodicals; Refractory materials -- Periodicals; Metallography -- Periodicals; Alliages réfractaires -- Périodiques; Matériaux réfractaires -- Périodiques; Métallographie -- Périodiques; Heat resistant alloys; Metallography; Refractory materials; Periodicals; Electronic journals; 669.73
• DOI: 10.1016/j.ijrmhm.2019.105127
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: Mössbauer spectroscopy has been used as a novel characterization technique to investigate Fe charge states, Fe complexes and hyperfine interaction parameters of different phases in WC-10Fe and WC-10(FeNi) materials sintered at three different temperatures (1350, 1430 and 1510 °C). The materials were characterized using standard cemented carbide quality control, and spectroscopic techniques to evaluate the structural changes and magnetic effects of the binder. The WC-10Fe grade had the highest Vickers hardness ranging from 1282 to 1320 HV30, for the different sintering temperatures. X-ray diffraction data showed the presence of WC and the metal binder phase, α-Fe and γ-FeNi. Transmission Mӧssbauer spectroscopy spectra obtained for the milled powders revealed only the α-Fe phase with a hyperfine magnetic field, Bhf ~33 T. Conversion electron Mössbauer spectroscopy on the sintered compacts revealed the presence of multiple fields, suggesting the possibility of minor phases present in the binder which were not detected using X-ray diffraction. The corresponding spectra for the sintered WC-Fe grades exhibited two magnetic fields with hyperfine parameters of ~33 T and ~17 T, respectively. These fields were assigned to α-Fe with some W atoms in solution and a W-rich Fe phase, respectively. The Mӧssbauer spectrum for the FeNi binder sample at the lowest sintering temperature of 1340 °C showed a paramagnetic doublet with an isomer shift, δ = −0.08 mm/s and electric quadrupole splitting, ∆ E Q = 0.00 mm/s and a weak hyperfine magnetic field, Bhf = 15.7 T. The doublet has been assigned to γ-FeNi and the magnetic component to a W-rich γ-FeNi phase. For the higher sintering temperature, a distribution of magnetic fields (~33 T, 25 T and 9 T) was evident in the Mössbauer spectrum. These magnetic fields were tentatively assigned to multiple W-rich γ-FeNi phases. Highlights: Mössbauer spectroscopy was used as a novel characterization technique on cemented carbides. Various phases were detected in the metal binders. The Fe binder phase consisted of two magnetic FeW phases. The FeNi binder consists of a paramagnetic and multiple magnetic phases.