Influence of rare-earth element doping on interface and mechanical properties of WC particles reinforced steel matrix composites

Abstract

In this paper, WC particles reinforced steel matrix composites (WCP/SMC) doped with rare-earth elements Y, Ce, La, and Nd, are manufactured via powder metallurgy sintering. The interface and mechanical properties of WCP/SMC are theoretically and experimentally investigated. The microstructures are observed through SEM, EDS and XRD. The properties are determined by compression and micro-hardness tests. The effects of rare-earth element doping on interface and mechanical properties of composites are investigated. The results indicate that composites mainly consist of α-Fe, W2C, WC, and Fe3W3C. In addition, the doping can accelerate the inter-atomic diffusion of the atoms in the interfacial reaction zone, promote the formation of Fe3W3C phase, and widen the interfacial reaction zone. Doping of rare-earth elements can reduce the hardness difference between the interfacial reaction zone and the composite matrix from 10.15 to 5.71 GPa and increases the compressive strength from 296.7 to 659.2 MPa. First-principles calculations indicate that doping of rare earth can reduce the interfacial, formation, and dissolution energy between the WC particles and the iron matrix. Thus, the stability of the interfacial reaction zone and bonding between the WC particles and the matrix is improved. By comparing the results with first-principles based calculations, composites doped with Nd have the best relative reaction interface bonding and mechanical properties.