Patent GB-1431882-A (GB)
Title: Dispersion strnegthened metals and alloys
IPC: C22C1/10
Filed: 1972-02-04
Abstract: 1431882 Casting processes INDUSTRY SECRETARY OF STATE FOR 30 April 1973 [4 Feb 1972] 5250/72 Heading B3F [Also in Division C7] A metal or metal alloy strengthened by the dispersion therein of a compound of a metal and a non-metal is prepared by reacting the metal in the molten state with a substance containing the metallic or non-metallic constituent of the dispersed compound, the substance being in the form of, or contained in, a molten slag layer on top of the metal. For the metals Ni, Cr, Fe, steel, Ti, Pt, Co, Th, and their alloys, the slag may comprise CaF 2 , while for the metals Al, Cu, Zn, Pb, Ag, Mg, U, Pu, and their alloys, the slag may comprise alkali metal fluoride eutectics. The dispersed metal compound may be an oxide, arsenide, carbide, sulphide, boride, nitride, phosphide, or silicide, and may be formed by reaction of a metal component of the matrix with an oxide or corresponding constituent of the slag. Oxyanions of the slag may be reduced, for example nitrosyl compounds to nitrides, sulphates to sulphides, carbonates to carbides, and borax to borides. Oxide constituents of the slag may be reduced to form the metal component of the dispersed compound. Oxidation or reduction may take place electrochemically and an electric current may also be used to heat the slag bath. As shown, molten or solid metal is dropped from a reservoir 4 on to heated slag 6, forming a pool 7 and reacting with the slag to produce ingot 8 on cooled base plate 2. Current is passed between electrode 9 and ingot 8. In other processes, the electrode 9 is replaced by a plasma jet or a carbon arc, or by a consumable electrode made of the metal or metals to be reacted. Heating may be supplemented by using an induction coil. Reaction may take place in an inert gas or under reduced pressure. To assist the retention of dispersed particles in the molten metal a direct current potential may be applied across the metal pool-slag interface. In examples (1) a dispersion of Al 2 O 3  in Fe-Al alloy is made by melting an electrode consisting of a sectioned Fe rod having Al foil bound between the two halves in a slag containing CaF 2 , CaO and Al 2 O 3  in oxygen; (2) a dispersion of Y 2 O 3  in Ni is made by melting a Ni electrode containing Y foil in a slag containing CaF 2 , CaO and Y 2 O 3  in air; (3) a dispersion of TiB, in Al is made by melting an Al electrode in a slag containing KCl, KBF 4 , K 2 TiF 6  in argon; (4) a dispersion of titanium nitride in Fe is made by melting an Fe electrode containing Ti foil in CaF 2  in nitrogen; (5) a dispersion of titanium phosphide Fe is made by melting an Fe electrode containing Ti foil in mixture of CaF 2 , CaO and CaP, in argon; (6) a dispersion of vanadium silicide is Fe is made by melting an Fe electrode containing V foil in a mixture of CaF 2 , CaO and CaSi 2  in argon; (7) a dispersion of titanium carbide in Fe is made by melting an Fe electrode containing Ti foil in a mixture of CaF 2 , CaO, Al 2 O 3  and CaC 2  in argon; (8) a dispersion of Y 2 O 3  in Ni-Cr is made by melting a Ni-Cr electrode containing Y foil in a mixture of CaF 2 , CaO and Y 2 O 2  in air.