HETEROGENEITY GENERATION BY THERMODIFFUSIONAL MECHANISM IN RAPIDLY SOLIDIFIED AMORPHOUS-ALLOYS

Rapid solidification can produce amorphous alloys and materials with h omogeneous and microcrystalline structures. However, chemical, structu ral, topological and other heterogeneities are frequently observed in rapidly solidified materials. Chemical macro-heterogeneity in melt-spu n amorphous alloys is considered in this paper. In binary amorphous al loys (i.e. binary glass metals), it is expressed in I ising of metallo id content from the contact side to the free surface side of the melt spun ribbon. The thermodiffusional mechanism of this heterogeneity gen eration is investigated. A mathematical model of the melt-spinning pro cess was developed and numerically calculated for the case of binary a lloys. Simulation of the process showed that the concentration wave ap pears in the liquid alloy film during its quenching. This wave moves f rom the contact surface to the free surface, and the concentration het erogeneity is developed before the solidification begins. The amplitud e of. heterogeneity strongly depends on the thermo-physical properties of the material and the process parameters, The simulation results co mpare favorably with the experimental observation using X-ray. spectra l microanalysis.