Abstract: A magneto-optical recording medium containing a substrate formed from polymers which are prepared by polymerization without ring cleavage, of monomers comprising polycyclic olefins, such as norbornene, results in a recording medium having increased thermal dimensional stability and resistance to hydrolysis, and decreased moisture absorption and birefringence.

Abstract: By the inventive method, an amorphous material in powder form can be produced, whereby at least two starting components in powder form are mechanically alloyed by means of a milling process so that a boron component which cannot be alloyed mechanically can nevertheless be alloyed. According to the invention, a boron component in powder form is admixed to the starting components; this powder mixture is subjected to the milling process, an amorphous alloying component being formed from the starting components with embedded or deposited fine particles of the boron components; and the mixture powder so produced is subjected to an annealing treatment below the crystallization temperature of the amorphous alloy component for diffusing the boron into the amorphous alloy component.