7.2 The effect of different production methods

This chapter discusses the effect of different production methods. A wide composition range of amorphous alloys has been produced owing to the rapid developments of the production techniques. Most of the amorphous alloys contain transition metals as components, either in combination with each other or with metalloids, rare-earth elements, actinides or non-transition metals. There is also a group of amorphous alloys consisting of non-transition metals only, but their diffusion properties have not been investigated. The amorphous alloys are often produced by rapid quenching from the melt, mostly by melt spinning on a metal wheel. The so-called splat quenching of melt drops is less important for production of larger amounts. A significant feature of the amorphous materials produced by rapid quenching is that they may have different properties on the two sides of the foil due to the different quenching rates. Compositions of amorphous alloys which cannot be produced or only with great difficulty by rapid quenching can be produced in many cases by co-sputtering or co-evaporation. Other less common methods to produce amorphous alloys are electrolytic deposition, irradiation damaging, and ion-beam mixing. The local composition and the structure of amorphous alloys produced in these ways are usually poorly defined. The most recent method to produce amorphous alloys is a solid-state reaction of mixtures of appropriate metals. The solid-state reaction starts either from multilayer thin crystalline metal films or from mechanically alloyed mixtures of crystalline powders.