Effects of metal binder content and carbide grain size on the microstructure and properties of SPS manufactured WC–Fe composites

• Published in: Journal of alloys and compounds 2019-05, Vol.784, p.519-526
• Main Authors: Pan, Yafei, Liu, Aijun, Huang, Lei, Du, Yong, Jin, Yaqin, Yang, Xinyu, Zhang, Jiuxing
• Format: Article
• Language: English
• Subjects: Bend strength; Composite materials; Densification; Fracture mechanics; Fracture mechanism; Iron; Mathematical analysis; Maximum bending; Mechanical properties; Microstructure; Plasma sintering; Powder metallurgy; Properties; Spark plasma sintering; Thermodynamic calculations; Tungsten carbide; WC–Fe composites
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.01.057

In the research, an investigation has been carried out on the microstructure and mechanical properties of WC–Fe composites, with various Fe content and either fine- or coarse-grained WC. The WC/Fe composite powders were processed by powder metallurgy method and consolidated to high density by spark plasma sintering (SPS). According to the thermodynamic calculations, the sintering temperature was selected to be 1050 °C. The experimental results indicated that there existed two main phases of WC, α-Fe and one minor Fe3W3C phase in the WC–Fe composites, which was consistent with the thermodynamic calculations. Besides, the relative densities of the composites increased with the Fe binder content, while exhibited different trends for the fine- and coarse-grained composites. Among the WC–Fe hard alloys, the composite with fine-grained WC and 30 wt % Fe binder possessed the highest hardness of 60.5 HRC. The maximum bending strength of 1851 MPa was attained for the composite with coarse-grained WC and 70 wt % Fe binder. The fracture mechanism of the composites was a combination of transgranular failure, intergranular failure, and Fe binder plastic tearing. •Thermodynamic calculations were used to design the sintering temperature.•Phase evolution in the sintering was analyzed by thermodynamic calculations.•The densification behavior of the SPS prepared composites was investigated.•The fracture mechanism of the WC–Fe composites was studied.