A SAXS study of rapidly solidified Al-base amorphous alloys containing nanometer-scale precipitates

Abstract

Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan(Received August 21, 2000)(Accepted in revised form December 18, 2000)Keywords: Small-angle X-ray scattering; Nano-structure; Shear; Al-base amorphous alloy1. IntroductionRecently, Inoue et al. developed Al alloys with excellent mechanical strengths by rapid solidification[1]. The microstructures of the alloys consist of amorphous particles 3 to 10 nm in diameter in an fcc-Almatrix, and these microstructures are considered to be responsible for its high strength. Sizes of theprecipitates may be kept within nano-meter length scales during nucleation, probably due to therelatively low precipitation temperature of Al metal and low growth rate of the non equilibrium phasesoccurring frequently in the crystallization process of amorphous phase [2].In the single roller spinning, thermal transport is estimated to be much faster than momentumtransport in the puddle of Al liquid alloys cast on the chill. And a solid boundary layer will formadjacent to the chill surface and will propagate into the melt puddle to form the ribbon [3]. Conse-quently, the high shear rate S at the thin boundary layer is obtained by the melt-spinning with a highcircumference velocity V