PROCESS FOR PRODUCING ALLOYS

Abstract: A process for producing alloys, particularly iron-base alloys containing magnesium, wherein the alloy constituents are molten under pressure of an inert gas and the melt is rapidly solidified in a chill mold. As a result of this rapid solidificatlon, the magnesium is retained as a fine dispersion or separate phase, allowing a high magnesium recovery rate in the ductlle cast irons or compacted graphite cast irons, treated with said alloys. The apparatus for this process consists of a charge vessel (24) far an alloy charge, means (22) for receiving the molten alloy and for rapid solidification of the alloy and means (66) for supplying inert gas under pressure to the vessel.

Description: APPARATUS AND PROCESS FOR PRODUCING ALLOYS The present invention is directed to a process and apparatus for the manufacture of alloys, more particularly but not exclusively certain alloys that have particular utility in treating molten cast iron to produce ductile and compacted graphite cast irons. It is known that controlled quantities of magnesium added to a melt of ordinary gray cast iron causes the carbon to form in a spheroidal shape and thereby produces ductile cast iron with greatly improved tensile strength and ductility compared to gray cast iron. The amount of magnesium retained in the cast iron for this purpose is generally from about 0.02 to about 0.08X by weight of iron. Compacted graphite cast iron is also produced by incorporating magnesium into molten cast iron. The amount of magnesium retained in the compacted graphite cast iron is of the order of about 0.015% to 0.035% magnesium based on the weight of iron. The compacted graphite cast iron has improved tensile strength compared to gray iron and may possess greater resistance to thermal shock and greater thermal conducitivity than ductile cast iron. The known processes and apparatus for production of such alloys have a number of disadvantages notably pyrotechnics and magnesium recovery, and it is an object of the present invention to provide improved such processes and apparatus which may in addition find usefulness in the production of other alloys. According to one aspect of the invention a process for alloy production, e.g. production of a predominantly iron alloy containing magnesium, comprises forming a molten charge of the alloy constituents in an atmosphere of inert gas and transferring the molten charge into cooling means for rapid solidification thereof. Where an iron/magnesium alloy is to be produced the inert gas-should be inert to magnesium vapour e.g. Argon and at a pressure greater than the vapour pressure of magnesium at the melt temperature. The process may comprise forming an iron and magnesium alloy charge, supplying and maintaining the inert gas pressure, and heating the charge to melt temperature in the inert gas atmosphere, or comprise forming a melt of iron, supplying and maintaining the inert gas pressure, and adding magnesium to the iron melt to form the molten charge. The addition of the magnesium to the iron melt and transfer of the molten iron/magnesium charge to the cooling means may be substantially simultaneous. The invention also extends to an alloy produced by the above defined process. In accordance with a further aspect of the invention apparatus for alloy production, e.g. an iron/magnesium alloy as above, comprises a charge vessel for an alloy charge, means to receive molten alloy from the charge vessel for rapid solidification thereof and means to supply inert gas under pressure to the vessel. The apparatus may comprise means to heat the material in the charge vessel e.g. an electric induction furnace, and may also comprise a pressure vessel (to contain the said inert gas pressure) in which is positionned the charge vessel. The receiving means may comprise a chill mould or a receiver in proximity to the charge vessel e.g. above or below the vessel. The vessel and the chill mould or receiver may also form a single enclosure. The charge vessel may have an opening at the top thereof for receiving an alloy charge and receiving means having a chamber therein and an opening at one end thereof, the receiving means being in a generally horizontal position with the opening at one end thereof located in proximity to the said opening in the charge vessel, and means for rotating the charge vessel and receiving means in the same direction to bring the receiving means into a generally vertical position to receive molten alloy from the charge vessel for rapid solidification of the molten alloy. The receiver may have an end portion that extends beyond the opening to the chamber therein, said extended end portion forming an enclosure over the opening of said charge vessel that connects the opening in the charge vessel with the opening to the chamber in said receiver. In a further form apparatus for producing an iron/magnesium alloy may comprise a vessel having an opening for receiving an iron-magnesium alloy charge, a receiver having a chamber therein and an end portion which is affixed to said vessel to form an enclosure for the opening in said vessel, which enclosure connects said opening with the chamber in said receiver, said receiver being in a generally horizontal position, means for heating the charge in said vessel to melt temperature and means for rotating the vessel and the receiver in the same direction to bring the receiver into a generally vertical position to receive molten alloy from said vessel for rapid solidification of the molten alloy. The alloy charge to produce and iron/magnesium alloy is preferably predominantly iron and includes at least 0.5% magnesium by weight. It may also include at least 0.1X silicon, at least 0.# carbon and at least 0.05% cerium and/or other rare earth metals or at least 0. 170 nickel, the balance iron (by weight). The solidification of the charge in the cooling means is preferably with the charge under constraint therein to produce an alloy ingot. The inert gas, e.g. Argon, pressure used is preferably about 2109 g/cm2g (30 psig'). The heating of the charge to melt temperature is preferably carried out in a single enclosure. Where apparatus is used of the type that includes a vessel for heating the charge of raw material to melt temperature and a chill mold for rapid solidification of the alloy melt while held under constraint, the process may comprise the steps of placing the chill mold opening in a location in proximity to an opening in the vessel, supplying a charge which is predominantly iron and includes at least about 0.5% magnesium to said vessel, supplying and maintaining the charge in an atmosphere of an inert gas under pressure of at least about 2109 g/cm2g (30 psig) heating the charge to melt temperature in said inert gas atmosphere, transferring the molten alloy from the vessel into the chill mold through said openings, and solidfying said melt while held under constraint in said chill mold to produce an alloy ingot. This may include the step of placing the chill mold in a generally horizontal position with the chill mold opening in a location in proximity to an opening in the vessel and rotating the vessel and chill mold in the same direction to bring the chill mold into a generally vertical position for receiving the alloy melt from said vessel. The apparatus in a preferred form may comprise an electric induction furnace for heating the iron-magnesium charge of raw material to melt temperature, a chill mold for receiving the alloy melt and for rapidly solidfying the melt while holding it under constraint, said chill mold being positioned above said furnace with the opening into the mold chamber located in proximity to an opening at the top portion of said furnace, means for supplying and maintaining the furnace and chill mold in an atmosphere of inert gas at a pressure greater than the vapour pressure of the magnesium at melt temperature while the alloy is in molten condition, means for heating the raw material charge to melt temperature and means for transferring the molten alloy into the chamber of the chill mold through said openings for rapid solidification to produce an alloy ingot. The chill mold may be a generally horizontal position while the charge is heated to melt temperature and the apparatus include means for rotating the furnace and chill mold to bring the chill mold into a generally vertical position for receiving the molten alloy from said vessel, the chill mold may have an extension projecting out from said opening to cover the opening in said vessel and form a single enclosure. The apparatus may also comprise a pressure vessel, a charge vessel positioned therein having an opening at the top thereof for receiving a charge of iron, a chill mold receiver positioned at the top of said charge vessel, said chill mold receiver having an opening at one end thereof located in proximity to the opening in said charge vessel and in position to receive molten alloy from said charge vessel for rapid solidification of said molten alloy, means for supplying inert gas under pressure into said pressure vessel said chill mold having means associated therewith for supplying magnesium material to the iron charge in said charge vessel for reaction therewith to produce said molten alloy while said iron charge is maintained under the said inert gas pressure. Where an iron charge is first melted before magnesium is added, it may start from solid in the charge vessel and be heated to melt therein by appropriate means. The apparatus of the invention may include means for tilting said charge vessel to transfer the iron charge into said chill mold receiver and in which the means for supplying magnesium material to said iron charge is actuated by the tilting of said charge vessel to supply the magnesium material into said iron charge. In accordance with the present invention alloys predominantly of iron and containing magnesium may be produced under pressure of an inert gas preferably greater than the vapour pressure of magnesium at the melt temperature used in forming the alloy. To this end, a graphite crucible, furnace or other suitable charge vessel with appropriate means for heating the raw materials to melt temperature is preferably positioned within an exterior pressure vessel. When the alloy melt is ready, it is poured into a chill mold such as a graphite receiver or dish wherein the melt is thereby rapidly solidifed into the desired iron magnesium alloy under pressure of an inert gas. For best results the melt is solidified under constraint in a particular form of graphite receiver that is preferably affixed to the heating crucible. If desired the charge vessel and chill mold may be combined to form a single enclosure and inert gas under pressure may be fed into the enclosure to eliminate use of the exterior pressure vessel. Also if desired, the magnesium can be added to a charge of molten iron held under pressure of an inert gas. As a result of rapid solidification, the magnesium in the alloys of the present invention is retained as a fine dispersion or separate phase within the iron matrix. Since the magnesium exists as a fine dispersion in the alloy, the interaction between the magnesium and molten gray cast iron being treated in the foundry may take place at a multitude of isolated sites. This is of advantage in that there is a higher recovery of magnesium in the treated cast iron and reduction in pyrotechnics during treatment as compared to that experienced with the iron-magnesium alloys made in conventional manner. For best results, the opening into the chill mold is located in proximity to an opening in the alloy furnace crucible. This is of advantage to reduce the free volume exposed to the stream of melt poured into the chill mold receiver which reduces the loss ofmagnesium by vaporization during the pour and thereby increases the amount of magnesium recovered in the alloy. Additionally, the magnesium vapor tends to be confined and constrained inside the mold so that the alloy may be produced in a clean, safe and economical manner. The chill mold in the form of an enclosure provides the maximum chilling surface in contact with alloy melt for a most rapid solidification and resulting high recovery of magnesium which is retained as a fine dispersion in the iron alloy matrix. In the preferred structure, the chill mold and furnace are combined into a single enclosure. In accordance with the process of the present invention, the selected raw materials for the alloy are charged into the graphite crucible preferably in the form of an induction furnace and suitable means for recording the temperature such as a thermocouple is inserted into the charge. The exterior pressure vessel is evacuated and then pressurized with a gas which is inert to molten iron and magnesium vapour such as Argon at a pressure above the vapour pressure of the magnesium at the selected melt temperature. In general a pressure of at least about 2109 g/cm2 g (30 psig) is employed and the preferable range of pressure is about 3515 to 5273 g/cm2g (50 to 75 psig). Heat is applied to melt the selected raw materials which for the iron alloys of the present in general, be about 1250 to about'13500C. Reaction be magnesium and iron alloy ingredients will generally take about five minutes whereupon the alloy melt is poured int mold and rapidly solidified. The outer vessel is depressu and the ingot of alloy when cool is removed from the mold. In one preferred form of apparatus a tilting induction having a graphite chill mold receiver mounted in a horizonta at the top portion of the furnace is employed. After the all is formed the induction furnace is rotated to pour the melt in; receiver which is moved into a vertical position by rotation o furnace. A stationary furnace may also be used with the receiv positioned below the furnace. In such case, the alloy melt is p into the receiver from the bottom of the furnace in conventional manner. The receiver may also be mounted on top of a stationary furnace and the alloy melt may be transferred into the receiver by differential pressure between the receiver and furnace established in known manner. Further details and advantages of the present invention will be understood in connection with the following description of the drawings which illustrate some preferred embodiments and in which: Fig. 1 illustrates one form of preferred tilting induction furnace with chill mold receiver positioned at the top portion of the furnace which is enclosed inside a pressure vessel. Fig. la is a top view of the pressure vessel 10 when completely open to illustrate preferred means for rotating the induction furnace. Figs. 2 and 3 show a top and a side view respectively of the bottom portion of the chill mold receiver of Fig. 1; Figs. 4 and 5 show a top and a side view respectively of the top portion of the chill mold receiver of Fig. 1; Fig. 6 illustrates a top view of the furnace of Fig. 1 with the chill mold receiver in place thereon; Fig. 7 is a sectional view taken on line A-A of Fig. 6; Figs. 8A, B, C and D illustrate operation of the furnace and chill mold receiver of Fig. 1; Fig. 9 illustrates a modified embodiment of the invention using a stationary bottom pour furnace with a chill mold receiver positioned below the furnace; and Fig 10 illustrates a second embodiment of the chill mold receiver of Fig. 6. Fig. I illustrates a preferred form of apparatus in which 10 is a conventional pressure vessel lined with a suitable refractory 11 to contain any melt that leaks out of the charge vessel or receiver. A charge vessel such as induction furnace 12 provided with a conventional electrical heating coil 14 is mounted in pressure vessel 10 on shaft 13 so that the induction furnace may be rotated through an arc of about 900 (Figs. 8A and 8C) by rotating shaft 13. The shaft 13 for rotating the charge vessel extends through a pressure seal 20 in the side wall of pressure vessel 10 so that the shaft and charge vessel can be rotated from outside the vessel 10. A chill mold receiver 22 is mounted in proximity to the graphite pot or crucible 24 of the induction furnace preferably by affixing the receiver against the top of the induction furnace as illustrated in the drawings. If desired, the chill mold may be sealed against the top of the furnace. Details of the structure of the chill mold receiver is best shown in Figs. 2-5. As there shown the chill mold 22 is preferably a two part mold having 2 bottom portion 26 and a top portion 28. The bottom portion of the mold comprises a generally rectangular solid integral frame 30 having an integral bottom wall 32 that extends from one end 34 of the frame toward the second end 36 over a major portion of the length of the frame to leave an opening 38 large enough to accommodate the mouth of the pot 24 of the induction furnace (see Fig. 7). Bottom wall 32 has a taper 40 that slopes down toward opening 38. One side of the bottom wall 32 is flush with one edge of frame 30 and it extends up a distance of about one-half the height of the frame. The frame 30 is provided with a plurality of bolt holes 42 so that the bottom portion may be bolted to the top portion 28 and the assembled chill mold receiver bolted against the top of induction furnace 12. The top portion 28 of the chill mold receiver 22 (Figs. 4 and 5) comprises a solid rectangular plate 44 that corresponds in size to the bottom portion 26. A plurality of bolt holes 46 are drilled through the plate in position to mate with bolt holes 42 for assembling the two parts of the mold. Plate 44 is provided with an opening 48 in position to be aligned with the larger opening 38 in the bottom portion 26. The thickness of plate 44 is reduced in the area surrounding opening 48 to provide a relatively thin wall section 50 and a tapered section 52. The area of the thin wall section 50 is the same size and it is adapted to align with the opening 38 in the bottom portion of the mold. The tapered section 52 is also aligned with the taper 40 in the bottom portion 26 of the mold when the two parts are assembled (Fig. .7).. The chill mold receiver may be of a suitable material and preferably graphite. As best illustrated in Fig. 7, the two parts of the mold are sealed together by bolts (not shown) with the tapers 40 and 52 facing each other and the assembled chill mold receiver is bolted against the top of induction furnace 12 by any conventional means such as bolts (not shown) that pass through the mold and are drawn tight in the body of the furnace. When assembled the chill mold has an interior chamber 54 that terminates in a tapered opening 53 that receives the molten iron-magnesium alloy from the crucible 24 of induction furnace 12. Figs. 1 and 8A-D illustrate operation of the apparatus for producing iron-magnesium alloys of the present invention. Pressure vessel 10 has a cover 56 pivotally mounted over the open mouth of the vessel The charge of selected raw materials such as ordinary iron and magnesium metal are supplied to the graphite crucible 24 of the induction furnace through the aligned openings 48 and 38 in the chill mold receiver. In the preferred structure, a cover 58 is thereupon pivotally mounted at 60 over the open mouth of the crucible 24 in any convenient manner and a second cover 62 is affixed in any convenient manner over the opening 48 of the chill mold. Temperature recording means such as a thermocouple 63 is inserted into the charge through openings in covers 58 and 62 and the thermocouple is clamped to the furnace. The opening in cover 58 is made large enough so that cover 58 may pivot relative to the thermocouple when furnace 12 is tilted for pouring the melt. Indicator 65 shows the temperature of the melt and a pressure gauge 67 records the pressure inside vessel 10 in known manner. When the charge is ready cover 56 is closed over the open mouth of pressure vessel 10 and preferably sealed shut in known manner. Air is evacuated from inside vessel 10 as by a conventional vacuum pump 64 and an inert gas such as Argon from a suitable source of supply 66 is fed into vessel 10 to establish and maintain an inert gas pressure above the vapor pressure of magnesium at the selected melt temperature. Heat is generated by supplying electricity from a conventional motor-generator unit 68 to melt the charge and cause reaction of the iron and magnesium which, in general, will only take about five minutes after the melt is formed in a small furnace such as that illustrated in the drawings. In an alternate procedure molten iron may be charged to the crucible 24 and after the melt is under inert gas pressure, the magnesium may be added to the melt in any convenient manner as will be obvious to those of ordinary skill in the art. After the melt is formed and reaction is completed, furnace 12 is rotated by shaft 13 to move the longitudinal axis of crucible 24 from vertical position into horizontal position and to move the longitudinal axis of chamber 54 of the chill mold 22 from horizontal position into vertical position. As a result, the melt is poured from the crucible 24 into chamber 54. The stream of molten alloy metal pivots the cover 58 outwardly away from the mouth of crucible 24. Tapers 52 and 40 help to direct the molten stream into chamber 54 and the extended end portion of the chill mold along with cover 62 encloses the open mouth of the charge vessel 12 and connects the open mouth with the opening 53 to the chamber 54. When the charge vessel 12 is sealed to the receiver 22 to form a single enclosure inert gas under pressure may be supplied directly to the enclosure which eliminates the need for the pressure vessel 10. As most clearly shown in Fig. 8C, the proximity of chamber 54 to the induction furnace crucible 24 materially reduces the exposed portion of the stream of molten alloy to reduce vaporization of magnesium during the pour. The rapid solidification of the molten alloy under constraint within the chill mold receiver further reduces vaporization of magnesium all of which contributes to a high recovery of magnesium in the alloy for a clean and safe operation. The molten alloy is rapidly solidified in graphite receiver 22 and for this reason the walls 44 and 32 on opposite sides of chamber 54 are each of about the same thickness as that of the melt when inside chamber 54 to provide an effective cooling medium or heat sink for rapid cooling and solidification. As a result, the magnesium in the alloys of the present invention is retained in the iron matrix as a fine dispersion or separate phase which as brought out hereinabove is of advantage for treating cast iron with the alloy of the present invention to produce ductile or compacted graphite cast irons. The graphite chill mold receiver is held in the vertical position shown in Fig. 8C until the alloy ingot has'solidified whereupon the induction furnace is again rotated back into vertical position (Fig. 8D). Vessel 10 Is depressurized, cover 56 is opened and the resulting alloy ingot 70 is removed from the receiver by unbolting and removing the top portion 28 from receiver 22. A modified embodiment for carrying out the process of the present invention is illustrated in Fig. 9. This embodiment comprises a conventional pressure vessel 72 identical to pressure vessel 10. A stationary crucible or furnace 74 with electrical induction heating coil 76 is positioned in the vessel. The induction furnace 74 is a conventional furnace provided with a bottom pour hole. 76 which is closed by a stopper or plug 78. The bottom plug 78 is lifted to clear the pour hole by any known means such as by rods 80 and 82 which are pivoted at 84. An eccentric 86 upon rotation will lift rod 82 and thereby rod 80 will move upwardly in vertical directionto lift the plug 78 and open the pour hole for bottom pour. A graphite chill mold receiver 88 is positioned below the furnace in proximity to the pour hole of the furnace to receive the alloy melt. The graphite receiver comprises two identical portions 90 and 92 which are bolted together (not shown) at one end 94 and the second end of each portion preferably has a flange 96 which is bolted to the bottom of the furnace to join the receiver and furnace together. The graphite receiver 88 is a rectangular enclosure provided with an opening 98 that is aligned with the pour hole 76 for receiving the alloy melt from furnace 74. Operation of this embodiment is the same as set forth for the embody ment of Fig. 1 except that the induction furnace 74 is stationary and the chill mold receiver 88 is positioned below the furnace to receive the alloy melt from the bottom of the furnace through pour hole 76. The molten iron alloy Is held under constraint in receiver 88 during rapid solidification. Figure 10 illustrates a second embodiment of the chill mold receiver 22. The embodiment of Figure 10 is identical to chill mold receiver 22 with the exception that cover 62 is replaced by means for adding magnesium to the charge of solid or molten iron in crucible 24. The specific means for adding solid magnesium to the iron charge in crucible 24 comprises a tube 100 preferably affixed at an angle to base 110 which makes a friction fit into opening 48 in the top of chill mold receiver 22. An iron wire 120 extends through holes drilled in pieces of magnesium 105 and then through a hole in the cover 115 of tube 100. A conventional stop 132 at the bottom of wire 120 secures the pieces of magnesium in place on the wire. The top end of wire 120 terminates in loop 130 which can move freely through the hole in cover 115. A second wire 125 which has one end secured to the inside of vessel 10 is passed through loop 130 to secure the magnesium 105 inside tube 100. The iron is charged to crucible 24 through opening 48 in the top of chill mold receiver 22. The tube 100 is secured to chill mold receiver 22 by inserting base 110 into hole 48 in the top of the receiver. By rotating shaft 13 and furnace 12 a few degrees clockwise, wire 125 is withdrawn from loop 130 to permit wire 120 and the magnesium 105 to drop into the molten iron contained in crucible 24. The addition of magnesium to the molten iron is made when the molten iron is at the desired temperature and when vessel 10 is pressurized with inert gas. The magnesium may be added to the iron charge to be treated at any desired time by extending the wire 125 through a seal in the side of vessel 10 so the wire 1.25 can be withdrawn from loop 130 from outside vessel 10. In accordance with the present invention, the alloys are prepared using conventional raw materials. These raw materials include magnesium, magnesium scrap, magnesium silicide, mischmetal or one or more rare earth metals per se or cerium or cerium silicides, silicon metal, ferrosilicon, silicon carbide, nickel, nickel scrap and ordinary pig iron, iron, or steel scrap as is conventional in the art for preparing alloys used as a reagent for treating cast iron to produce ductile or compacted graphite cast iron. The alloy may have any desired composition but for best results the alloy will have a low magnesium content of about 0.5 to about 4.0% by weight of magnesium with the balance being iron. The alloy may include silicon which for best results will constitute from about 0.1 to about 10.0% by weight of silicon and the alloy will usually include from about 0.5 to about 6.5X by weight of carbon. Cerium and/or other rare earth elements may be included which is of advantage to increase the amount of magnesium recovered in the alloy. Further details concerning the advantage of cerium and/or other rare earth elements in the alloy are described in copending E.P.applications published under nos: 90653 and 90654. Best results are achieved when the cerium and/or other rare earth elements constitute from about 0.05 to about 2.0% by weight. Nickel may also be included to increase the magnesium recovered in the alloy. Combinations of nickel and cerium and/or other rare earth elements may also be included to advantage for the same purpose as more fully described in copending application Serial No. (ref T-129) filed under even date herewith. In general, best results are obtained wIth about 0.1 to about 10% by weight of nickel. The amounts of raw materials used in forming the alloy of the present Invention are controlled in known manner to form an alloy having the selected composition. In most cases the alloy will include trace amounts of other metals such as calcium, barium or strontium customarily present in the raw materials. In one example 5910 gms. of solid iron and 90 gms. of magnesium were charged into induction furnace 24 and an alloy ingot 2357-29 was produced using the process described hereinabove. The Argon pressure in vessel 10 was maintained at 4218 g/cm2g (60 psig) and the charge heated to 13000C and held at 13000C for three minutes. The alloy ingot recovered from the chill.mold receiver 22 contained 0.98% by weight of magnesium. The amount of magnesium recovered from the charge was 63% and the alloy contained by weight 3.54% carbon and 3.32X silicon. In another example 400 gms. of CSF No. 10 (Foote Minerals) and 60 gms. of magnesium metal and 3580 gms. iron were charged into induction furnace 24 and alloy ingot 2357-7 was produced using the process described hereinabove. The charge was heated 2 to 13000C and held under Argon gas pressure of 4218 g/cm g (60 psig) for three minutes at 13000C. The alloy ingot recovered from the chill mold 22 contained 1.33% magnesium by weight and 0.86% cerium by weight. The amount of magnesium recovered from the charge was 83% and the alloy contained by weight 3.77% carbon and 4.20% silicon. The CSF No. 10 is the trade name of Foote Minerals for an iron alloy containing about 38X silicon, about 10% cerium and about 2.0X rare earth elements (total 12% rare earth elements) by weight. The same procedure described above was employed using a total charge of 6000 gms. consisting of iron and the following added materials: Charge in Grams Alloy Analysis by. Weight Alloy CSF 10 Mq t Ms % Ce 2357-4 450 90 1.17 0.66 2357-3 300 90 1.04 0.48 The amount of magnesium recovered from the charge which contained 450 gms. of CSF 10 was 76X and the alloy contained by weight 3.8X carbon and 4.18 silicon, 68X of the magnesium was recovered from the charge which contained 300 gms. of CSF 10 and the alloy contained 3.67X carbon and 4.14* silicon by weight. In the following examples, the process described hereinabove was employed by charging the following materials into furnace 24. The charge was heated to 13500C and the melt held at that temperature for three minutes. The Argon gas pressure was 5273 g/cm2g (75 psig). In these examples, the melt from furnace 24 was poured into an open graphite eight inch diameter dish (not shown). TABLE I ALLOY Charge in Grams Iron Nickel Cerium Magnesium 2314-76 3000* 61 (Nickel Shot) 7 (Cerium Silicide)** 77 2314-57 3000* 30 (Nickel Shot) 6 (Cerium Silicide)** 75 2314-54 3000* 15 (Nickel Shot) 6 (Cerium Silicide)** 75 * The iron charged in alloy 2314-76 contained 3.89% carbon and 4.49% silicon and 0.092% cerium. The iron charged in alloys 2314-57 and 54 contained 3 95X carbon, 4.41X silicon and 0.084% cerium. ** The cerium silicide charged in all cases contained 25X cerium, 35% silicon and 35% iron and a total of rare earth elements of 27%. The alloy ingot produced in the chill mold dish had the follow ing compositions: TABLE II Elemental X by Weight Ingot Alloy Grams Carbon Silicon Magnesium Nickel Cerium Iron 2314-76 3046 4.05 4.38 2.00 2.26 0.13 balance 2314-57 3086 3.71 4.47 1.64 0.89 0.14 balance 2314-54 3005 3.58 4.39 1.49 0.47 0.11 balance The alloy exhibited an exceptionally high recovery of magnesium in the charge. In alloy 2314-76, the magnesium recovery was 79X by weight, 67% by weight of magnesium was recovered in alloy 2314-57 and 60 by weight of the magnesium charge was recovered in alloy 2314-54. These examples illustrate the beneficial effect of using nickel in the process.

Claims: CLAIMS 1. A process for alloy production comprising forming a molten charge of the alloy constituents in an atmosphere of inert gas and transferring the molten charge into cooling means for rapid solidification thereof. 2. A process as claimed in Claim 1 wherein the alloy is a predominantly iron alloy containing magnesium. 3. A process as claimed in Claim 2 wherein the inert gas pressure is greater than the vapour pressure of magnesium at the melt temperature. 4. A process as claimed in claim 2 or Claim 3 comprising forming an iron and magnesium alloy charge, supplying and maintaining the inert gas pressure, and heating the charge to melt temperature in the inert gas atmosphere. 5. A process as claimed in Claim 2 or Claim 3 comprising forming a melt of iron, supplying and maintaining the inert gas pressure, and adding magnesium to the iron melt to form the molten charge. 6. A process as claimed in Claim 5 in which the addition of magnesium to the iron melt and transfer of the molten charge of iron and magnesium to the cooling means is substantially simultaneous. 7. An alloy produced by the process of any of the preceding claims. 8. Apparatus for alloy production comprising a charge vessel for an alloy charge, means to receive molten alloy from the charge vessel for rapid solidification thereof and means to supply inert gas under pressure to the vessel. 9. Apparatus as claimed in Claim 8 for the production of a predominantly iron alloy containing magnesium. 10. Apparatus as claimed in any of Claims 8 to 10 comprising means to add magnesium to a molten charge of iron in the vessel to form the said alloy charge. 11. Apparatus as claimed in any of Claims 8 to 11 in which the inert gas supply means supply and maintain an atmosphere of inert gas under pressure greater than the vapour pressure of magnesium at melt temperature. 12. Apparatus for producing a predominantly iron alloy containing magnesium which comprises a vessel having an opening for receiving an iron-magnesium alloy charge, a receiver having a chamber therein and an end portion which is affixed to said vessel to form an enclosure for the opening in said vessel, which enclosure connects said opening with the chamber in said receiver, said receiver being in a generally horizontal position, means for heating the charge in said vessel to melt temperature and means for rotating the vessel and the receiver in the same direction to bring the receiver into a generally vertical position to receive molten alloy from said vessel for rapid solidification of the molten alloy.

Inventors: WELLS III, JAMES ENOCH
Applicants: ELKEM METALS COMPANY
Application year: 1983
Main classification: B22D27
IPC codes: C22C33, B22D27