초록 ▼

High density, generally microscopically homogeneous corrosion-resistant chromium-uranium metal alloys for ammunition use (particularly for spherical pellets or shot) can be made from U 238 or an isotopic mixture high in U 238 (such as "depleted uranium") and at least about 10 atomic % chromium. The

High density, generally microscopically homogeneous corrosion-resistant chromium-uranium metal alloys for ammunition use (particularly for spherical pellets or shot) can be made from U 238 or an isotopic mixture high in U 238 (such as "depleted uranium") and at least about 10 atomic % chromium. The alloys can also contain one or more metals of Group VIII, first triad, of the Periodic Table, and a variety of other elements used, for example, in making ferrous metals. Major factors to be considered in formulating the alloy are density, melting point or melting range, passivity or chemical or biological inertness, resistance to segregation in the molten phase and upon rapid cooling (chromium-poor phases or regions being particularly undesirable), and compensation for any loss of free chromium due to formation of intermetallic or other forms of combined chromium. The uranium content in the alloy is preferably less than 70 atomic %. Rapid cooling of the chromium-uranium or chromium-uranium-Group VIII metal melt, e.g. by the shot tower technique, avoids undesirable segregation effects which can detract from corrosion resistance. The shot tower may optionally contain a non-oxidizing atmosphere.

대표청구항 ▼

1. A solid, generally spherical, generally corrosion-resistant, iron-chromium-uranium metal pellet consisting essentially of a generally corrosion-resistant iron-chromium-uranium alloy which has been cooled from the molten state to below its solidification temperature quickly enough to prevent the f

1. A solid, generally spherical, generally corrosion-resistant, iron-chromium-uranium metal pellet consisting essentially of a generally corrosion-resistant iron-chromium-uranium alloy which has been cooled from the molten state to below its solidification temperature quickly enough to prevent the formation of any segregated uranium-rich phase containing less than 10 atomic percent chromium, thereby forming a fine-grain alloy structure, said iron-chromium-uranium alloy having a specific gravity of at least about 8.4 and consisting essentially of about 3 to about 35 atomic-% uranium, about 10 to 35 atomic-% chromium the major amount of the alloy, by atomic-%, being iron, the uranium of said iron-chromium-uranium containing more than 99.3% of the U 238 isotope. 2. A pellet according to claim 1 wherein the iron-chromium-uranium alloy contains an amount of chromium sufficient to make said alloy resistant to corrosion in moisture-containing environments at normal ambient outdoor temperatures. 3. A pellet according to claim 1 wherein the amount of chromium is at least about 12 atomic percent. 4. A pellet according to claim 1 consisting essentially of an iron-chromium-uranium alloy in which the iron content is less than 87 atomic-%, said iron-chromium-uranium alloy having been cooled from the molten state to a temperature approaching ambient in less than about one minute. 5. A solid, generally spherical metal shotgun pellet consisting essentially of a solid iron-chromium-uranium alloy having a specific gravity of at least about 8.4, said pellet having been formed by cooling to ambient temperature, in less than about a minute, a molten solution comprising a uranium isotope mixture in molten stainless steel, said isotope mixture containing more than 99.3% U 238 ; said solid alloy consisting essentially of about 3 to about 35 atomic % solid uranium, having essentially the isotopic distribution in said molten solution, about 50-87 atomic-% iron, and about 10-35 atomic-% chromium. 6. A pellet according to claim 5 wherein said uranium isotope mixture contains less than 0.3% U 235 . 7. In a process for making high density ammunition from uranium containing at least the naturally-occurring amount of the U 238 isotope, the steps comprising: (a) blending together, as elements or intermetallic compounds, the elements consisting essentially of about 3 to about 35 atomic % uranium, about 10-35 atomic % molten chromium, and about 50-87 atomic-% iron, in the molten state, thereby obtaining essentially a solution, (b) cooling the resulting solution to about ambient temperature quickly enough to prevent the formation of a segregated uranium-rich phase containing less than 10 atomic % free chromium, thereby obtaining a solid metal pellet having a fine grain structure and a specific gravity of at least about 8.4. 8. A method according to claim 7 wherein the blend produced according to said step (a) is formed into molten drops which are exposed to normal ambient temperatures, thereby cooling the drops to solid, generally spheroidal pellets in less than about one minute. 9. A method according to claim 7 wherein at least part of the chromium and at least part of the iron are added as an iron-chromium alloy or mixture. 10. A method according to claim 9 wherein the iron-chromium mixture or alloy is (a) ferro-chromium obtained from reduced chromium oxide-containing ore, (b) scrap stainless steel, or (c) mixtures of (a) or (b) with a metal of Group VIII, first triad, of the Periodic Table. 11. An iron-chromium-uranium alloy having stainless properties and a specific gravity of at least about 8.4, said alloy consisting essentially of a fine-grain structure consisting essentially of: 3-35 atomic-% uranium, which uranium has at least the naturally-occurring amount of the U 238 isotope, 50-87 atomic-% iron, and 1- 35atomic-% chromium, said alloy being substantially free of solid segregated phases locally containing less than 10 atomic-% free chromium. 12. An iron-chromium-uranium alloy according to claim 11 consisting essentially of: 15-35 atomic-% uranium 50-73 atomic-% iron, and 12-20 atomic-% chromium, said alloy having a melting point below the melting point of iron. 13. An iron-chromium-uranium alloy according to claim 11 containing 0-5 atomic-% of a combination of other metals or nonmetals typically found in stainless steel, said metals or nonmetals being selected from silicon; a Group VIII element, other than iron; carbon; manganese; molybdenum; aluminum; copper; vanadium; wolfram; zirconium; boron; tantalum; or niobium; and further containing up to trace amounts of nitrogen, selenium, phosphorus, hydrogen or oxygen. 14. A shotgun pellet according to claim 5 wherein said pellet is about 1-10 mm in diameter and said alloy consists essentially of a fine-grain structure consisting essentially of: 15-35 atomic-% uranium, 50-73 atomic-% iron, and 12-20 atomic-% chromium. 15. An iron-chromium-uranium alloy according to claim 11 containing 12-20 atomic-percent chromium.