Abstract
The current work investigated the manganese–tungsten binary system by studying the microstructure of a mechanical alloy of tungsten–35 at.% manganese, sintered at 1225, 1275, 1350, and 1425 °C. Consistency of the results is evaluated through thermodynamic modeling of the manganese–tungsten phase diagram. The microstructural constituents were characterized qualitatively and quantitatively in terms of the type of phases and the content of manganese in the tungsten rich-phase using X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDS). The XRD patterns revealed peaks associated with a tungsten-rich phase and manganese oxide (MnO) in the first set of samples while the patterns of the second set showed the strong peaks related to a manganese-rich phase and manganese dioxide (MnO2). Backscattered images showed a distinct two phase microstructure in the first set of samples as compared to a three-phase microstructure in the second set of the samples. The maximum observed solubility of manganese in tungsten is 12 ± 3 at.% after sintering at 1350 °C for 90 min, compared to 9.3 at.% at 1268 °C based on a thermodynamic model. The maximum observed solubility of tungsten in manganese is about 10 at.% in the high temperature solid, compared to 7.4 at.% and 4.6 at.% in the solid and liquid phases respectively at the peritectic temperature of 1268 °C.
Published Version
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