Interface reaction and diffusion of tungsten-fiber/Zr-based bulk metallic-glass matrix composites

Zr-based metallic-glass matrix composites, which were reinforced by continuous tungsten fibers, were prepared by melt infiltration casting. The interface reaction and diffusion were analyzed by using X-Ray diffraction, SEM and EPMA. The influence of Nb content of the matrix alloy on the interface reaction and diffusion was also investigated. The results illustrate that for the Zr₅₅Al₁₀Ni₅Cu₃₀ matrix composites an interface eutectoid reaction between W fiber and Zr in the liquid phase takes place and a W₅Zr₃ phase is formed at the interface. The interface moves to the direction of the liquid phase. For the matrix alloy containing Nb, the addition of Nb in the liquid causes a significant change of interface reaction. Nb in the liquid phase exhibits a preferential adsorption at the surface of the W fiber, thus reduces the adsorption of Zr atom in the liquid phase at the surface of the W fiber. The activity of absorbed Zr at interface is decreased, and depresses the interface eutectoid reaction between W fiber and liquid. In this case the interface is a simple diffusion layer only. At the same time the diffusion coefficient of Zr in the W is decreased by Nb addition and the interface moves to the direction of W fiber.