Effect of Fe addition on glass forming ability and mechanical properties in Zr–Co–Al–(Fe) bulk metallic glasses

A series of Zr56Co28−xAl16Fex (x = 0, 1, 2, 4, 8 and 14, respectively) bulk metallic glasses (BMGs) are cast using water-cooled copper mold casting technique. It is found that the addition of Fe impacts the structural, thermal and mechanical properties remarkably. Enhanced glass forming ability (GFA) and compressive plasticity are obtained for x ≤ 4. Higher Fe contents deteriorate the GFA and the mechanical performance. It is further revealed that Fe addition can significantly affect the internal states thus allowing to tune the yield strength and the plasticity of BMGs. Among the investigated alloys, Zr56Co26Al16Fe2 BMG has good GFA and excellent mechanical properties, e.g. a high fracture strength of over 2 GPa and a pronounced compressive critical fracture strain of 15.1%.

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► A minor substitution of Co by Fe causes an increase of GFA in Zr–Co–Al–Fe BMGs.
► More Fe contents deteriorate the GFA in Zr–Co–Al–Fe BMGs.
► Existence of brittle intermetallic phases may deteriorate the mechanical performance.
► Zr56Co26Al16Fe2 BMG has good GFA and excellent mechanical properties.