GB915693A - Improvements in the manufacture of alloys of refractory metals - Google Patents

Abstract

A metal boride such as aluminium boride can be produced in the one-step process of preparing a refractory metal alloy (see Group II) by reacting an oxide of at least one refractory metal which includes the element boron with a reducing metal such as aluminium or magnesium, the reaction being performed in the presence of a non-reacting metal such as copper or by using excess reducing metal; and in the presence of a molten salt capable of dissolving the slag-forming oxide of the reducing metal, the temperature being above the melting-point of the metal or metals. For example, in preparing aluminium boride contained in an alloy of boron and aluminium, an intimate mixture of boron oxide B2O3, and cryolite is added to excess molten aluminium at 970 DEG C. contained in a crucible under an argon atmosphere whereby, after the reaction in which the Al2O3 slag formed dissolves in the molten cryolite, the melt is heated to 1120 DEG C. and the metal phase separated. The ratio of Al2O3 to cryolite may be between 1:2,2 and 1:8,0.ALSO:A refractory metal alloy is prepared in a one-step process by reacting an oxide of at least one refractory metal of the group titanium, molybdenium, chromium, zirconiumin maniganese, vanadium, thorium, beryllium idium, tungsten, uranium, and including the element boron (see Group III), with a reducing metal such as aluminium or magnesium, the reaction being performed in the presence of a non-reacting metal such as copper or by using excess of the equivalent amount of reducing metal, both being capable of alloying with the refractory metal, and at a temperature above the melting-point of the metal or metals, e.g. between 900 DEG and 1600 DEG C., whereby the refractory metal oxide is reduced to the metal and a slag-forming oxide of the reducing metal is formed, and in the presence of a molten salt capable of dissolving the slag. Other oxides may be included such as Fe2O3 for alloying. The molten salt preferably consists of a Group I to III metal chloride and/or fluoride having a boiling-point above 700 DEG C., e.g. cryolite with or without ZnCl2, NaCl and CaF2, AlCl3, CaCl2, or KCl. The ratio of oxide slag formed to the salt may be between 1 : 2.2 and 1 : 8.0. The molten salt and oxide slag may be separated from the alloy formed and electrolysed to recover the reducing metal, e.g. Al, and salt, e.g. cryolite, for recycling. Numerous specific aluminium-titanium alloys for use as master alloys in steel production are disclosed containing 4.6 to 82.4% Ti. Other master alloys specified have the following compositions:-(a) Ti 5.6%, Mg 93.2%; (b) Mo 8.94%, Al 89.6%; (c) V 10.1%, Al 88.1%; (d) Zr 6.43%, Al 92.3%; (e) Mn 7.9%, Al 3.1%, Cu 88.95%; (f) Ti 7.6%, Al 3.6%, Cu 85.05%; (g) B 4.3%, Al 93.8%; (h) Ti 19%, Al 21%, Fe 26%, Mn 33%; the balances being insolubles.