Aug. 30, 1966 M. B. VORDAHL METHOD OF PRODUCING HOMOGENEOUS ALLOYS 3,269,825 CONTAINING. REFRACTORY METALS Filed June 8, 1963 2 Sheets-Sheet 1 /WWAAV7OA. M/1. TOM A. VOAAAAL Aly 4. AttorneyI Aug. 30, 1966 M. B. voRDAHL 3,269,825 METHOD OF PRODUCING HOMOGENEOUS ALLOYS CONTAINING REFRACTORY METALS Filed June 18, 1963 2 Sheets-Sheet 2 /W/AWTO A. // TOW A. VOAAAAA. ay % AtAfforney 3,269,825 United States Patent Office Patented August 30, 1966 2 into the form of a consumable electrode for vacuum arc 3,269,825 melting. However, it has been found that the molyb METHOD OF PRODUCENG. HOMOGENEOUS AL. denum powder has a pronounced tendency to stratify in LOYS CONTANNG REFRACTORY METALS Milton B. Vordah, Beaver, Pa., assignor to Crucible Steel such an electrode with the resultant production of a melt Company of America, Pittsburgh, Pa., a corporation of containing dense layers of unmelted molybdenum. Still New Jersey further attempts have been made by utilizing a mixture Filed June 18, 1963, Ser. No. 288,686 of titanium powder plus molybdenum powder and, al 20 Claims. (CI. 75-10) though molybdenum distribution in the resulting melts have been found to be generally improved, titanium pow This invention relates to methods of producing alloys der with the required low oxygen content is commercially containing Substantial amounts of refractory metals, such 0 unavailable. Recognizing the necessity for introducing as the element molybdenum and, particularly, to titanium molybdenum in a physical form having relatively small base alloys containing, in addition to molybdenum, sub cross sectional areas, prior art attempts have also included stantial amounts of tin. the addition of molybdenum to the electrode in the form In the prior art production of molybdenum-containing 15 of foil or wire. However, such highly finished forms of alloys, difficulty has been encountered in obtaining sub molybdenum are quite expensive, making the use of such stantially complete dissolution of the high melting point physical forms economically impractical. element molybdenum in alloy compositions comprising a Therefore, it is an object of the present invention to base metal having a relatively much lower melting point. provide a method of obtaining substantially complete dis Thus, molybdenum, having a melting point of 2625 C., 20 solution of refractory metal additions, as molybdenum, as compared to a melting point of 1875 C., for zirconium, in relatively lower melting point base alloy compositions. or 1800 C. for titanium, and 1535 C. for iron, will not It is a further object of the invention to provide a meth readily dissolve in alloy compositions containing the lat od for producing alloy compositions having uniformly ter or other relatively low melting point elements as the distributed therethrough substantial quantities of molyb base metal of the alloy, except in those relatively few denum. instances where molybdenum forms low melting point eu It is a still further object of the invention to provide tectic alloys with the base metal, e.g., 65 weight percent alloys and products thereof comprising a base metal hav iron-35 weight percent molybdenum. However, full ad ing a melting point substantially lower than that of molyb vantage cannot be taken even of such favorable alloy denum and containing substantial quantities of the ele phase relationships unless it is possible to hold the same 30 ments molybdenum and tin, wherein the molybdenum in the liquid state for extended periods of time. This, component is substantially completely dissolved therein of course, is impossible, in usual vacuum arc melting pro and uniformly distributed therethrough. cedures, utilizing water-cooled, metal molds. Difficulties It is a particular object of the invention to provide are encountered principally in those situations, including, products comprising titanium base alloys containing mo but not limited to, usual vacuum melting procedures lybdenum and tin, and methods for making such alloys where the high reactivity of one or more alloy compo and products. nents, as titanium or zirconium, prevents holding the alloy The foregoing and other objects and advantages of the in a molten condition for appreciable periods of time. invention will be more readily apparent by an inspection The production of alloys, as base alloys of titanium and of the following specification and drawings, wherein Zirconium, or other alloys, as iron-, nickel- or cobalt-base 40 FIG. 1 is a photographic illustration of a section, in Superalloys, containing major additions of the latter ele elevation, of an ingot of a titanium-molybdenum-tin alloy ments, or other reactive metals, as aluminum, falls in this produced by a single vacuum arc melting, in accordance category. As a consequence, additions of molybdenum with the invention; to such base alloys result in nonhomogeneity of the result FIG. 2 is a similar view of an ingot, of substantially ing alloys as regards the molybdenum content thereof. the same composition as that shown in FIG. 1, but pro This difficulty in producing molybdenum-containing alloys duced in accordance with prior art practice, and is of present and increasing importance in view of the FIG. 3 is a similar view of an ingot of a titanium increased need for and use of alloys containing relatively molybdenum alloy produced in accordance with prior art high percentages of molybdenum. practice. Prior art attempts to incorporate molybdenum in sub 50 It is, of course, essential to the production of alloys stantial quantities in alloys wherein the base metal has exhibiting the maximum benefit of the intended molybde a substantially lower melting point than molybdenum num content thereof, and to the uniformity of the conse have generally been unsuccessful in obtaining alloy homo quent alloy properties throughout the mass of the alloy geneity, despite efforts to introduce the molybdenum in product, that the molybdenum content be completely dis various product forms which have been considered con 55 solved in the metal matrix. Complete dissolution of the ducive to better dissolution of the molybdenum. Attempts molybdenum, or other high melting point alloy compo have been made to produce alloys, for example, titanium nent, is essential, inasmuch as a single, undissolved, size base alloys, containing substantial quantities of molyb able inclusion of the refractory metal in an alloy ingot denum, by the consumable vacuum arc melting process, or other mill stock unit makes the same unfit for its in wherein a part of the consumable electrode comprises a 60 tended purpose. Any such inclusion, incorporated in a continuous molybdenum rod. Relatively homogeneous finished article subject to mechanical stress, as for exam molybdenum-containing alloys can be made by such a ple, a turbine blade or a structural component of an aero process but only by a series of consecutive remeltings of space vehicle, might well, because of its stress-raising the alloy melted from such an initial consumable electrode. character, cause the part to crack or rupture catastroph Successive remeltings, of course, add considerable expense ically. Thus, the aim of the present invention is not and make the alloys so produced commercially unfeasible. 65 production of uniformity of dispersion of the refractory However, no such procedures have been productive of metal alloy component, but, instead, is the virtually com substantially complete molybdenum dissolution and homo plete dissolution of such components in the base alloy geneity upon a commercially feasible basis. and elimination of unmelted refractory inclusions. As another example of prior art attempts to produce It is evident that the nature of the benefit conferred such alloys, molybdenum powder has been incorporated 70 by an alloying addition of the refractory metal and, with titanium sponge and the resultant mixture compacted consequently, the full realization of the benefits due to 3,269,825 3 4. the dissolution thereof in the base alloy, is dependent a beta microstructure. Such titanium base alloys are upon the alloy class involved or, indeed, upon the par highly useful in a variety of applications, for example, in ticular alloy under consideration. Therefore, it is fur high structural uses, in view of their superior formability ther evident, that the present invention, in the inventive high strength structural uses, in view of their superior method thereof, being directed to the attainment of sub formability and strengths as compared to alpha and alpha Santially complete dissolution of molybdenum and other beta titanium alloys. However, such superiority of cer refractory metals, is not limited to a single, restricted tain beta titanium alloys is offset to a great extent by rea class of alloys nor to any particular alloy composition. son of their relatively poor stability, particularly upon ex However, exemplary of alloys and products thereof de poSure to elevated temperatures. For example, the single riving substantial benefits from the practice of the inven 0. currently commercially significant beta titanium alloy, Ti tion, and in accordance with the foregoing objects, the 13% V-11% Cr-3%. Al, possesses the highest strength present invention provides structurally uniform, molyb weight ratio of any metallic sheet, but that alloy is denum-containing alloys and products, particularly those strengthened by the formation therein of intermetallic comprising titanium base alloys, specifically, alloys com compounds which, upon exposure of the alloy to a tem prising from about 6 to about 15%, preferably 10 to 12 or 15 perature of 600 F. for 100 hours, make the alloy almost 14% molybdenum, from about 4 to about 15%, pref glass-brittle. erably 4 to 8% tin, balance substantially titanium, where Therefore, a beta titanium alloy, strengthened by other in molybdenum, in powder form, is mixed with powdered means, e.g., by Solid-Solution strengthening, and hence tin, the powder mixture roll pressed into the form of thin less susceptible to such thermal instability, would be of flakes, the composite flakes are admixed with granules great utility.