Silver Tungsten alloy Tungsten copper alloy is composed […]
Silver Tungsten alloy Tungsten copper alloy is composed of tungsten and copper alloy, is a metal matrix composite material. Due to the large difference between the physical properties of copper and tungsten metal, it can not be produced by the casting method, and the powder alloy technology is generally used for production. Common alloys of copper content of 10% to 50%. Preparation of alloy powder metallurgy method, has good electrical and thermal conductivity, good high temperature strength and a certain degree of plasticity. Aluminum castings have feeder refueling, al-si class alloy solidification temperature range, riser feeding high efficiency, easy access to dense tissue castings. Other types of cast aluminum alloy solidification temperature range, riser feeding low efficiency, poor casting density. Aluminum is extremely easy to get in and oxidize, so the pouring system must ensure that the molten aluminum flows in faster and more smoothly to avoid agitation. A variety of casting methods are suitable for aluminum alloy castings. When the production is less, available sand casting, sand should be used to shape; mass production of important castings, the use of special casting. Metal casting high efficiency, good casting quality. Low-pressure casting is suitable for high-pressure-resistant water-resistant die-castings. Pressure casting can be used for thin-walled complex small pieces. Aluminum alloy is easily oxidized in the liquid state, the product of al2o3, melting point up to 2050 ℃, the density slightly larger than aluminum, was suspended in solid aluminum inclusions, difficult to remove, both to deteriorate the casting performance, but also reduce the mechanical properties of the casting Decreasing compactness. Liquid aluminum is also very easy to absorb hydrogen, precipitation precipitation, the formation of stomatal or pinhole defects. Refining method In order to slow down the oxidation of aluminum liquid and inhalation, aluminum alloy melting should be covered in the flux layer. At the same time the temperature of the preparation, the solubility of the metal and ceramic phase asked very small. Metallocene, defined in a narrow sense, refers to a class of materials in which metals and ceramic phases have interfaces in three dimensions in composite materials. In our country, the research on Cobalt chromium alloy superalloy is more thorough and thorough. Unlike other superalloys, Cobalt chromium alloy superalloy does not consist of an ordered precipitated phase that is firmly bonded to the substrate, but instead consists of a matrix of fcc that is solid-solution strengthened and a small amount of carbides distributed in the matrix. Casting Division Stanley superalloy is to a large extent rely on carbide strengthening. Pure cobalt crystals at 417 ° C are densely packed hexagonal (hcp) crystalline structures that are converted to fcc at higher temperatures. In order to avoid this conversion of Cobalt chromium alloy superalloy in use, virtually all Cobalt chromium alloy are nickel alloyed to stabilize the tissue from room temperature to the melting temperature.