Influence of Rare-Earth Substitution for Iron in FeCrMoCB Bulk Metallic Glasses

The effects of rare earth addition on the glass forming ability of Fe_50-xCr₁₅Mo₁₄C₁₅B₆M_x (x=0, 2 and M=Y, Gd) bulks and ribbons are studied. The thermal and structural properties of the samples are measured by a combination of differential scanning calorimetry (DSC), x-ray diffraction and scanning electron microscopy. Chemical compositions are checked by energy dispersive spectroscopy analysis. The copper mold casting technique leads to a fully amorphous structure up to 2 mm only for compositions containing Y or Gd. In the case of ribbons, a fully amorphous phase is observed for all the compositions. The roles of Y and Gd are discussed on the basis of melting behavior analyzed by high-temperature DSC. Such elements act as oxygen scavengers, avoiding heterogeneous nucleation.