Pt60Ni15P25 metallic glass ribbons prepared by a single-roll melt-spinning method were deformed in tension at a strain rate of 2 x 10-2 8-1 in the supercooled liquid region. In-situ observations of the deformation behaviour of the metallic glass ribbons were carried out using an optical microscope. It was found that a homogenous deformation of more than 200% elongation took place by a viscous flow of the supercooled liquid of Pt60Ni15P25 metallic glass at 523K, an intermediate temperature in the supercooled liquid region. In the case of the tensile tests after partial crystallisation at 543K, it was found that the residual supercooled liquid deformed preferentially without deformation of the crystalline solid, and therefore inhomogeneous deformation occurred.
