TEMPERATURE-DEPENDENCE OF THE FLOW-STRESS AND DUCTILITY OF ANNEALED AND UNANNEALED AMORPHOUS FE40NI40P14B6

The flow stress and ductility of amorphous Fe40Ni40P14B6 was investigated on asprepared and annealed ribbons over the temperature range 78 to 573 K. The embrittlement is characterized by a rise in the ductile-to-brittle transition temperature Tdtb, such that Tdtb≈Tanneal and sets in at temperatures as low as 423 K. The flow stress of Fe40Ni40P14B6 at room temperature is 2.21 GPa (320 ksi), in good agreement with the extrapolation from hardness measurements. The flow stress increases with decreasing temperature. The increase can be accounted for in dislocation-based models of the deformation of a metallic glass but is more difficult to understand in terms of a free volume model. © 1979 Chapman and Hall Ltd.