GB755835A - Process for producing grain stabilized metals and alloys - Google Patents

Abstract

Grain stabilised metals consisting of one or more of Pt, Ir, Os, Pd, Rh, Ru, Au, with or without the addition of one or more of W, Mo, U, Cr, Mn, Fe, Co, Ni, Be, Re, Ag and Cu are produced by melting the first listed metal or metals in a non-oxidising atmosphere and in the absence of a fluxing agent, incorporating into the fused metal at least one element capable of forming an oxidation at the fusion temperature of said metal, a non-volatile chemically stable oxide, evenly distributing said element, exposing the melt to an oxidising atmosphere to convert the metal to an oxide which forms a colloidal dispersion in the melt of between 0,02 and 2,5 gram equivalents of the oxide per litre. The elements comprise Be, Si, Al, Ti, Mg, Sc, Cr, Nb, Ca, Zr, Ni, Fe, Co, Y, La, Ce, Hf, Nd and other rare earth elements, Th, U, Ta, Ba, and W. If the base metal addition metals listed above are to be added to the alloy then this is done after the oxidation step. Pre-alloys may be used to add the oxides and in this case the elements form from 0,1-25 per cent by weight of the metal The pre-alloy may be made by reacting powdered constituents or by wrapping the elements in metal foil. The following alloy is disclosed (inter alia): .Pt.10-77.per cent .Pd.12-89.per cent .Ru.1-11.per cent Heat-treatment. The ingots of metal produced are hot-or-cold-worked in a conventional manner, a soaking anneal of 500 DEG -1100 DEG C. is stated to give the best results, and these temperatures are also suitable for "between anneals." Several examples of treatments are described. If catalytic properties are needed in the finished article reductions of area above 75 per cent are used. The following articles are specified: catalytic gauze, electrical contacts, spinnerets and laboratory ware. Pickling. Platinum-rhodium wire is pickled in a mixture of dilute aqua regia and ammonium chloride.