Abstract: A sintered, microcrystalline abrasive material consists of at least 99.5%, by weight, of .alpha.-Al.sub.2 O.sub.3 crystallites having a size of less than 2 .mu. and the material having a density of at least 97% of the theoretical density. This abrasive material has a very high abrasive property and can be used in grinding bands or discs.

Abstract: The invention relates to a process for the production of rare earth metals and alloys thereof. The process exploits the known advantages of metallothermal reduction techniques while decisively enhancing their reduction process. Rare earth halides and/or rare earth oxides are reduced in an electric arc furnace by means of one or several alkaline earth metals, preferably, calcium. Additives such as iron metals or other alloying elements, alkali- and/or alkaline earth metal salt, may be added to the electric arc furnace in a two-phase furnace operation. The reduction takes place in an atmosphere inert to rare earth metals, rare earth compounds, and alkaine earth metals. Agitation is produced in the metal in the furnace by eletromagnetic forces caused by a suitably selected current-to-voltage ratio for the electric arc, in order to achieve reduction in the shortest possible time and as completely as possible.