| With the rapid development of global economy, the material performance have become more sophisticated, especially in the wear industry, WCp/steel(iron) matrix composites having a wear resistance and toughness to meet the requirements of high-performance materials. The mechanical properties of the composite materials and thermal interface and the cracks are closely related. Firstly, using the first principle calculation WCp/steel(iron) base thermal and mechanical parameters of composite inter-phase, discusses the formation mechanism of the phase interface. Then high-energy ball milling powder mixed with vacuum sintering powders prepared WCp/steel(iron) matrix composites, focusing on the interface of WCp/steel(iron) matrix composite formation mechanism and compression fracture morphology, summed up the particle volume fraction impact of particle shape and composition of the matrix composites fracture surface, providing a theoretical basis for metal matrix composites road to industrialization.From the point of view of thermodynamics and mechanics described in the WCp/steel(iron) composite Fe3W3C compound can be used as a stable phase interface exists. Fe3W3C by calculating the elastic constants, indicating Fe3W3C meet mechanical stability conditions. In the theoretical analysis of WC/steel(iron) composite inter-phase generation mechanism:in all paths synthesis interface phase in, Fe, W and C elemental most easily direct synthesis Fe3W3C interface phase, but within the material Fe, W and too little C elemental content, so the main path interface W2C phase synthesis by reaction with Fe powder obtained, where o-W2C type most likely to generate Fe3W3C phase. Which is calculated by forming 3Fe+3/2o-W2C→Fe3W3C+1/2C is able to-3.45eV/atom; 3Fe+3h-WC→e3W3C+2C can be formed as a-1.09eV/atom. Combined with semi-empirical theory discussed composite mechanical properties of brittle phases, including the bulk modulus, shear modulus, Young’s modulus, hardness and an-isotropic properties. The hardness of the order of brittle phase is:h-WC>h-W2C>o-W2C>t-W2C>Fe3W3C; order of brittle phase bonding strength is:h-WC> h-W2C> o-W2C> Fe3W3C> t-W2C; in which Fe3W3C Young’s modulus is 436.7GPa and hardness is 9.96GPa.With the increase of the volume fraction of tungsten carbide, compressive strength of the composite increases first and then decreasing trend, when the volume fraction of particles is 45%, the maximum compressive strength; fracture mode from the quasi-cleavage fracture to brittle fracture transition; the degree of dissolution of the particles inside is also reduced, W2C consumption is reduced, resulting in reduction of the reaction product, namely, on the macro performance reduced width of the interface; the interface material is Fe3W3C, mainly generated by the reaction W2C with Fe occur. Compressive strength of steel-based composite material is less than the iron-based composite material, due to steel-based composite material of tungsten carbide particles dissolve more serious, and showed a trend completely dissolved; iron-based composite material tungsten carbide particles dissolve relatively small, and is formed around a complete interface. The compressive strength of non-spherical particles of the composite material is less than spherical particles composites, because the non-spherical tungsten carbide particles in the composite heating process, the structure tends to form slowly round, that is, non-spherical tungsten carbide particles have a transition to spherical tungsten carbide particles.WCp/steel(iron) based composite material compression experiment(pressing) process, micro-cracks initiation priority at the interface of materials, and extended to a large crack at the interface, resulting in material failure. Also during the extrusion process, a small fraction of tungsten carbide particles within the material will be brittle cracking phenomenon; non-spherical tungsten carbide, and more susceptible to cracking than the spherical particles.
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