Salient shear bands and second-phase addition interactions of bulk metallic glass matrix composite

Author： Qiu K. Wu X. Wang A. Zhang H. Ding B. Hu Z.

ISSN： 1543-1940

Source： Metallurgical and Materials Transactions A, Vol.34, Iss.5, 2003-05, pp. : 1147-1152

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Abstract

This article discusses Charpy impact testing and fracture morphology of the Zr_41.25Ti_13.75Cu_12.5Ni₁₀Be_22.5 bulk metallic glass matrix composite with long tungsten fibers. Energy to failure was measured via the impact test as well as by integrating the compressive stress-strain curves, and compared for various fiber fractions. Failure energy increased with fiber volume fraction by both measures. Observation of fracture surfaces was made by using scanning electron microscopy. The results show that the fracture surface of the unreinforced bulk metallic glass (BMG) exhibits three different regions, i.e., the impact zone, the transition zone, and the ridged zone, which have different morphology. The composites present uneven or jagged morphology on macroscopic scale, while the microstructure exhibits salient shear bands and second-phase addition interactions. Bridge formation between tungsten fibers is interpreted as evidence that the shear band propagation in the matrix is suppressed by the fibers. Furthermore, shear lips were observed for the composites containing over 50 pct, fiber volume fraction, showing a great improvement in toughness.