Deformation behavior in La-4Al-4N-4 metallic glass

We investigated the deformation behavior of the supercooled liquid in a La55Al2jNia)(at.%) metallic glass ribbon that has a wide supercooled liquid region of 65 K before crystallization. The deformation of the metallic glass was divided into three types, namely, homogeneous deformations with and without a stress overshoot and an inhomogeneous deformation. The supercooled liquid above the glass transition temperature (?,) exhibited a Newtonian viscosity and superplastic-lflce behavior during isothermal tensile deformation. The metallic glass was elongated as much as 1000 % at high strain rates ranging from 102 s'1 to 10° s~l without embrittlement. The maximum elongation to failure was in excess of 1800 % at a strain rate of 1.7x10 s'1 and at 503 K (J,+20 K, 0.7irj under about 40 MPa. 1999 Materials Research Society.