Glass forming ability and microstructure of hard magnetic Nd 60Al 20Fe 20 glass forming alloy

Abstract

Glass forming ability (GFA), magnetic properties and microstructure of Nd 60Al 20Fe 20 as-cast rod were investigated and further compared with Nd 60Al 10Fe 30 glass forming alloy. The rod prepared by suction casting with a diameter of 3 mm exhibits the typical amorphous nature in XRD pattern, distinct glass transition in DSC traces and hard magnetic properties. It is found that the diameter of cast Nd 60Al 20Fe 20 glassy rod is much larger than the critical section thickness ( Z c) of bulk metallic glass (BMG) predicted from DSC measurements. A few nano-crystalline particles with the structure and composition similar to A x phase in Nd–Fe alloys were found embedded randomly in amorphous matrix and could be the origin of hard magnetic properties of the as-cast rods. The GFA of the alloy appears to be enhanced by the precipitation of metastable nano-particles with small positive forming enthalpy and the real Z c of the alloy could be less than 1 mm predicted by parameter γ.