Abstract: A method of producing a silicon based alloy is described which comprises melting a silicon alloy containing greater than 50 wt. % silicon and preferably including aluminium. The melted alloy is then inert gas atomized to produce powder or a spray formed deposit in which the silicon forms a substantially continuous phase made up of fine, randomly oriented crystals in the microstructure. The alloy produced by the method has particularly useful application in electronics packaging materials and a typical example comprises an alloy of 70 wt. % silicon and 30 wt. % aluminium. Such an alloy is an engineering material which, for example, is machinable.

Abstract: A method and apparatus for the production of a deposit such as a bar (1) is provided. The deposit has a longitudinal outer surface (2) and a front face deposition surface (3). The spray deposition comprises atomized droplets produced by outer and inner sprays (4 and 5). The outer and inner sprays (4 and 5) are both directed such that, during deposition, a substantial proportion of droplets from both sprays are deposited on the front face (3) of the forming deposit. The inner spray (5) has a higher gas to metal ratio than the outer spray allowing an increase of both deposition and final product yield.

Abstract: A method of forming a deposit in which a spray of gas atomized molten metal or metal alloy is generated and directed at a substrate. The substrate is rotated about an axis of rotation and a controlled amount of heat is extracted from the molten metal or metal alloy in flight and/or on deposition. The spray is oscillated relative to the substrate, preferably along the axis of the substrate. With continuous production techniques involving a single pass, base porosity can be considerably reduced and in the formation of thicker deposits of discrete length, base porosity can be minimized and reciprocation lines can be eliminated or reduced in intensity.

Abstract: An introducing means for introducing particulate material into a molten metal, molten alloy or molten ceramic stream, or spray of droplets formed therefrom is disclosed. The introducing means has an annular introducing chamber defining an opening through which the stream may be teemed. The chamber includes an inlet, and an outlet positioned about the opening. The outlet allows particulate material to exit from the introducing chamber at a plurality of positions about the opening so that, in use, the particulate material is introduced substantially uniformly about the stream or spray. The particulate material is preferably supplied by means of a hopper, a screw feeder for feeding material to the hopper to a mixing chamber, and a transport gas for transporting the particulate material from the mixing chamber to the introducing chamber.

Abstract: Metal is spray cast onto a moving substrate using at least two sprays, the first of which has a solid fraction greater than 20% at the time the spray contacts the substrate, but less than the solid fraction of the second spray.

Abstract: A molten metal gas-atomizing spray-depositing apparatus has an atomizer which employs a pressurized gas flow for atomizing a stream of molten metal into a spray pattern of metal particles being initially hotter than the solidus temperature of the metal. The apparatus also has a substrate system which includes an outer substrate of metallic foil and an inner substrate for supporting the outer substrate. The outer foil substrate is movable relative to the metal particles in the spray pattern thereof and disposed below the atomizer for receiving on a surface of the foil a deposit of the particles in the spray pattern to form a product on the outer foil substrate. The outer foil substrate is of a thickness which is less than a predefined maximum thickness at which the capacity of the foil to absorb heat from the deposit is equal to the latent heat and super heat, if present, of the deposit.

Abstract: Apparatus for the production of powders or spray deposits is provided in which a metal or metal alloy stream is broken up into atomized droplets by primary jets of atomizing gas. In order to remove further heat from the atomized droplets, secondary jets are positioned adjacent the primary jets for directing cooling fluid in the form of cryogenic liquified gas at the atomized droplets. The apparatus permits the formation of coarser powders, powders from alloys with a wide solidus/liquidus gap in a shorter atomizing chamber, or spray deposits with increased yield of deposited material.

Abstract: There is provided a method of spray deposition in which a stream of liquid metal or metal alloy is atomized inside a spray chamber into a spray of atomized droplets. A metal or metal alloy collector is rotated about an axis transverse to the mean axis of the spray and in the path of the spray so that a deposit is formed about the collector with a bond between the deposit and the collector sufficient to isolate the interface from oxygen penetration. The collector is then retained as an integral part of the final product and further processed to substantially eliminate porosity in the region of the bonded interface. The collector and the deposit may be the same or different materials, and the bond between the deposit and the collector is preferably enhanced by plasma heating in the region disposition. The invention also provides a plant for carrying out the preferred method arc plasma heating.

Abstract: A method of forming a deposit in which a spray of gas atomized molten metal or metal alloy is generated and directed at a substrate. The substrate is rotated aobut an axis of rotation and a controlled amount of heat is extracted from the molten metal or metal alloy in flight and/or on deposition. The spray is oscillated relative to the substrate, preferably along the axis of the substrate. With continuous production techniques involving a single pass, base porosity can be considerably reduced and in the formation of thicker deposit of discrete length base porosity can be minimized and reciprocation lines can be eliminated or reduced in intensity.

Abstract: A method and apparatus for the production of spray deposited ingot, disc or bar is provided it which a spray of gas atomized molten metal or metal alloy particles generated with an atomizing device is directed onto a collector. The collector is rotated about an axis of rotation and a controlled amount of heat is extracted from the atomized particles in flight and on deposition. In order to maintain a substantially constant distance between the atomizing device and the surface of the deposited metal or metal alloy there is relative movement between the atomizing device and the collector. The spray is directed so that the main axis of the spray and the axis of rotation of the collector are inclined at an angle to one another; and the spray is oscillated so that the main axis of the spray oscillates relative to the axis of rotation of the collector.

Abstract: A device for gas atomising a liquid stream, such as a stream of molten metal or metal alloy, has an atomising device including, for example, an annular opening for receiving the stream. The atomising device is arranged for applying atomising gas to the stream so as to form a spray of atomised particles. At least a part of the atomising gas, and preferably all, is applied by means movable relative to the stream whereby movement is imparted to the spray to achieve improved uniformity or control of deposition by moving the spray either by moving the atomising device with a symmetric gas flow field relative to the stream or by oscillating or rotating a rotor mounted within the atomising device and arranged to produce an asymmetric gas flow field.

Abstract: A method of casting is provided in which a rheocast deposit is formed by atomizing a stream of molten metal or metal alloy by subjecting the stream of molten metal or metal alloy to relatively cold gas directed at the stream, and directing the resultant spray of metal droplets at a collector. The deposit is provided with a rheocast type structure by extracting heat from the metal droplets such that the material deposited at the collector includes solid phase particles in a liquid phase which, upon solidification, forms a microstructure characterized by a fine network of microsegregate at the grain boundaries or coring across the grains and which, above the solidus region of the said metal or metal alloy, exhibits thixotropic properties. The rheocast deposit may be thixotropically deformed either during or after deposition.

Abstract: A device for gas atomizing a liquid stream, such as a stream of molten metal or metal alloy, has an atomizing device including, for example, an annular opening for receiving the stream. The atomizing device is arranged for applying atomizing gas to the stream so as to form a spray of atomized particles. At least a part of the atomizing gas, and preferably all, is applied by means movable relative to the stream whereby movement is imparted to the spray. This movement leads to improved uniformity or control of deposition.

Abstract: A method and apparatus for manufacturing a shaped precision article from molten metal or molten metal alloy wherein a gas atomized stream of molten metal or molten metal alloy is directed at a collecting surface to form a coherent deposit, the stream being cooled in flight by the atomizing gas, which is at ambient, preferably room temperature, sufficient heat being extracted by the relatively cold atomizing gas from the stream of molten metal in flight such that formation of the coherent deposit is independent or substantially independent of the thermal properties and temperature of the collecting surface, provided the temperature of the collecting surface is below the melting point of the metal or metal alloy being sprayed; and the deposit is worked as by a die to form the precision metal or metal alloy article.