Surface oxidation of FeSiB amorphous alloy and its effect on metallic glass fiber reinforced cement mortar

Amorphous alloys and metallic glass fibers have superior properties for both structural and functional applications. In this study, Fe₇₈Si₉B₁₃ amorphous alloys were annealed in air at 25-400 °C for 0-60 min to introduce surface oxidation. Pristine fibers with a volume content of 0, 0.25, 0.5, 0.75, 1, 1.25 and 1.5 vol% and surface-oxidized fibers with a content of 0.5 vol% were used to prepare fiber reinforced cement mortars. Structural, thermal, magnetic and mechanical properties were characterized for pristine fibers, oxidized fibers and mortar specimens. Air-annealed alloys remain amorphous and produce a partially oxidized surface, which reduces saturation magnetization. Mortars reinforced by pristine fibers exhibit 6.4% and 32.4% of increase in compressive strength and flexural strength respectively, due to fiber-paste interfaces. Surface oxidation of the fibers improves the efficiency of load-transfer and, as a result, further enhances the strengths of fiber reinforced mortar. This study demonstrates that surface oxidation of metallic glass fibers is a viable strategy to enhance performances of cement-based materials.