Although rapid solidification has been used for generations to refine the grain sizes of materials, its effects are most significant when it succeeds in converting the liquid state into a glass. This is because homogeneous materials can be made in this way that have distinctly different compositions, as well as different molecular structures, from traditional materials. The liquids of interest are alloys, in the widest sense. These may consist of two or more metals, two or more polymers, two or more ceramic compounds, or other combinations. When they have been converted into glasses they may be useful in that form, or the glass may be the precursor to devitrified forms that cannot be created in any other way. Such materials often have unusual combinations of chemical and physical properties including strength, magnetic hardness or softness, electric response, catalytic ability and corrosion resistance.