摘要:
A cast composite material is prepared by furnishing an aluminum-based matrix alloy and forming a mixture of free-flowing boron carbide particles and the aluminum-based matrix alloy in molten form which is stirred to wet the matrix alloy to the boron carbide particles and to distribute the particles throughout the volume of the melt. The molten mixture is then cast. The fluidity of the molten mixture is maintained by (a) maintaining the magnesium content of the matrix metal below about 0.2% by weight, or (b) starting with a matrix metal containing less than 0.2% by weight magnesium and adding further magnesium to the mixture a short time before casting, or (c) having at least 0.2% by weight titanium present in the mixture.
摘要:
A metal-matrix composite material includes a matrix having magnesium in an amount of more than about 0.3 weight percent but no more than about 2.5 weight percent, an alloying element of about 0.8 to about 2.5 weight percent iron or from about 1.0 to about 2.5 weight percent manganese, and the balance aluminum and impurities. Dispersed throughout the matrix is a plurality of metal oxide particles present in an amount of more than about 5 volume percent but no more than about 25 volume percent of the total volume of the matrix and the particles. This material may be cast into casting molds. After casting is complete and during solidification of the matrix alloy, a high volume fraction of intermetallic particles is crystallized in the matrix alloy. The total of the volume fractions of the metal oxide particles and the intermetallic particles is from about 10 to about 40 volume percent, preferably from about 25 to about 40 volume percent.
摘要:
A device for measuring metal purity, comprising a receptacle for holding a sample of molten metal, the receptacle being made, at least internally, from an insulating refractory material and having a bottom wall provided with a hole containing a filter element. The bottom wall is substantially impermeable to air except at the hold. An enclosed collection vessel is positioned below the receptacle for collecting molten metal which passes through the filter element from the receptacle, the collection vessel having an opening permitting extraction of gas from within the vessel to enable a vacuum to be generated within the vessel during use of the device. A leak-tight seal is established between the receptacle for molten metal and the collection vessel to permit vacuum generated in the collection vessel to draw molten metal into the collection vessel from the receptacle through the filter. The receptacle for molten metal has a heat diffusivity value that is sufficiently low that, in use, the temperature of the molten metal in the receptacle does not fall below the liquidus temperature in a period of time required for the vacuum to draw a fixed amount of molten metal sufficient for metal purity testing purposes through the filter and into the collection vessel from the receptacle. The invention also relates to a corresponding method, and to novel parts of the device.
摘要:
A method and apparatus for detecting and measuring suspended solid particles in a molten metal, even if the metal also contains liquid and/or gaseous inclusions. The method involves moving molten metal through an orifice of predetermined hydrodynamic diameter provided in an electrically non-conductive barrier. As the molten metal is moved through the orifice, a current path is established by passing a current through the orifice from electrodes positioned on opposite sides of the barrier. Changes in voltage of the current are measured as the metal is drawn through the orifice, and the number of particles suspended in said metal drawn through the orifice is detected from the voltage changes. The metal, immediately before being moved through the orifice, is conveyed through a passage defined by an electrically non-conductive surface positioned in the current path, the passage including a region having a hydrodynamic diameter of between 2 and 10 times the hydrodynamic diameter of the orifice, at least a part of the region being of substantially constant hydrodynamic diameter. The provision of the passage upstream of the orifice has the effect of removing substantially all liquid and gaseous inclusions from the molten metal before the metal passes through the orifice.