Contact interaction at the composites interfaces between the microcrystalline particulate and the molten matrix

Abstract

The peculiarities in structure formation of interfacial zones at the composite’s boundaries between the molten Fe–C–B–P–Mo matrix and the filler’s solid phases of W₂C and WC that have microcrystalline structure were investigated in this work. The structure of the interfaces was studied by methods of metallographic and automatized quantitative analyses. The interfaces of dissolution-and-diffusion type were observed between the matrix and the filler. A dissolution rate of the filler’s microcrystalline phases of W₂C and WC was shown to decrease by ~ 1.7–1.8 times as against that of the crystalline phases of the same composition. This result was explained considering the dependence of an average shift of atoms from the equilibrium positions in the lattice on linear size of the phases. Since the average size of the microcrystalline phases is ~ 25 times smaller than that of the crystalline phases, the average shift of microcrystalline phase atoms from the equilibrium positions decreases by ~ 1.7 times. Correspondingly, the microcrystalline particulate dissolves in the molten matrix at the lower rate than crystalline one which prevents from formation of undesirable brittle compounds in the structure of composite’s interfacial zones during infiltration.