Abstract: A furnace for growing large single crystals from materials having high meng temperatures using the vertical solidification of melt method. The crucible containing the melt being encased in a muffle with vertically oriented heating rods arranged in a circular pattern around the outside of the muffle. The tops of the heating rods being electrically connected to a continuous graphite ring, and the bottoms of equal numbers of rods being electrically connected to two semi-circular sections of graphite. The power feeds for the heating rods being vertically brought into the furnace from the bottom for electrical connection to the semi-circular sections of graphite.

Abstract: A method for the production of improved, transparent single crystals having a corundum structure under conditions of minimum thermal strain, comprising the optimum orientation of growth planes of a seed crystal in a melt substantially parallel to the vertical side wall means of a crucible, and heating and subsequent cooling the melt, thereby nucleating on the seed crystal.

Abstract: The unidirectional solidification of a metal-ceramic composite in a system omprising the positioning of a seed crystal in a crucible, adding a portion of premelted ceramic material, a metallic material, and the remainder of the premelted ceramic. The temperature of the ceramic material is raised to about 50.degree.C above its melting point and then slowly decreased with a corresponding increase in the flow of an inert coolant gas through the system thereby unidirectionally solidifying the material to produce a single crystal having the orientation of the seed.