Formation and properties of Mg-based metallic glasses in Mg-TM-X alloys (TMCu or Ni; XSn, Si, Ge, Zn, Sb, Bi or In)

Abstract

Amorphous Mg-TM-X (TMCu or Ni; XSn, Si, Ge, Zn, Sb, Bi or In) alloys are produced by a singlee-roller melt-spinning technique. It is found that, by varying the quenching speed, the amorphous phases can readily be formed in Mg-TM-Sn alloys and the critical thickness for forming complete amorphous ribbons can be expanded to about 150–200 μm. Calorimetry studies reveal that the reduced glass temperature T rg in Mg-TM-Sn metallic glasses is about 0.52, which is quite low compared with that of the conventional good glass formers. A fracture tensile strength as high as 900 MPa is recorded for Mg 80Ni 15Sn 5 metallic glass, which is much higher than that of the conventional Mg-based crystalline alloys. Substitution of Sn by Sb, Bi or In in these Mg-based alloys can also result in metallic glass formation; however a high quenching speed is needed and the tensile strengths are much reduced. The glass formability in these Mg-based alloys is discussed within the framework of current metallic glass formation theories.