Fe-(Cr,Mo)-(C,B)-Tm Bulk Metallic Glasses with High Strength and High Glass-Forming Ability

Abstract

The glass-forming ability and mechanical properties of (Fe,Co)-(Cr,Mo)-(C,B)-Tm glassy alloys have been investigated. The (Fe,Co)₄₈Cr₁₅Mo₁₄C₁₅B₆Tm₂ glassy alloys were prepared in a cylindrical form with a diameter of 10 mm. These alloys have high glass forming ability (GFA) enough to produce a single glassy rods with a diameter above 10 mm. The largest supercooled liquid region before crystallization in (Fe_1−xCo_x)₄₈Cr₁₅Mo₁₄C₁₅B₆Tm₂ alloys is 90 K for Co₄₈Cr₁₅Mo₁₄C₁₅B₆Tm₂. These glassy alloys have high fracture strength of over 4100 MPa for the entire composition range and the strength level is almost independent of Co content. The high GFA is attributed to the retardation of precipitation of the crystallized phases caused by the formation of the stabilized glassy local structure in which short-range ordered trigonal prisms are connected through glue effect of Tm element. The combination of high strength and high glass-forming ability indicates high possibility of applying the (Fe,Co)-(Cr,Mo)-(C,B)-Tm glassy alloys to various industrial materials.