Tungsten alloy is based on tungsten to join other elements of the alloy. In the metal, the highest melting point of tungsten, high temperature strength and creep resistance and thermal conductivity, conductivity and electron emission performance are good, the major, in addition to a large number of used for the manufacture of cemented carbide and alloy additives, tungsten and its alloys are widely used In the electronics, electric light industry, but also in the space, casting, weapons and other departments for the production of rocket nozzles, die-casting mold, armor-piercing missile, contacts, Tungsten Alloys heating and insulation screen.
Tungsten alloy use
Tungsten was first used to make incandescent filaments. 1909 US Ku Liji (W.D.Coolidge) tungsten powder suppression, remelting, forging, drawing process made of tungsten wire, tungsten wire from the rapid development of production. In 1913, Langmuir and Rogers discovered that tungsten and thorium (also known as thorium tungsten) emit electron properties better than pure tungsten, and began to use tungsten and thorium, which is still widely used. 1922 developed a good anti-sagging performance of the tungsten wire (known as doped tungsten wire or tumbronic tungsten wire), which is tungsten wire research in the significant progress. Tungsten Alloys The sintered tungsten wire is widely used for excellent filament and cathode materials. 50 ~ 60 years, the tungsten-based alloy has been extensively explored, hoping to develop in the 1930 ~ 2760 ℃ work tungsten alloy, for the production of aerospace industry, the use of high temperature components. Among them, tungsten rhenium alloy is more studied. Tungsten ingot and processing technology has also been studied, using self-consumable arc and electron beam smelting to obtain tungsten ingots, and by extrusion and plastic processing made of certain products; but the melting ingot grain thick, poor plastic , Processing difficulties, low yield, and thus smelting - plastic processing technology failed to become the main means of production. In addition to chemical vapor deposition (CVD) and plasma spraying can produce very few products, powder metallurgy is still the main means of manufacturing tungsten products.
Tungsten use temperature is high, Tungsten Alloys simply using solid solution strengthening method to improve the high temperature strength of tungsten is not effective. But on the basis of solid solution strengthening and then diffusion (or precipitation) strengthening, can greatly improve the high temperature strength, to ThO2 and precipitation of HfC diffusion particles to enhance the best effect. At about 1900 ℃ W-Hf-C and W-ThO2 alloys have high high temperature strength and creep strength. In the tungsten alloy used below the recrystallization temperature, the method of hardening is carried out to produce strain hardening, which is an effective reinforcing method. Such as fine tungsten wire has a high tensile strength, the total processing deformation rate of 99.999%, 0.015 mm in diameter fine tungsten wire, tensile strength at room temperature up to 438 kg force / mm
In refractory metals, tungsten and tungsten alloys have the highest plastic-brittle transition temperatures. The sintered and melted polycrystalline tungsten has a plastic-brittle transition temperature of between about 150 ° C and about 450 ° C, resulting in difficulties in processing and use, Tungsten Alloys whereas monocrystalline tungsten is below room temperature. The interstitial impurities, microstructures and alloying elements in the tungsten material, as well as plastic processing and surface conditions, have a significant effect on the plastic-brittle transition temperature of the tungsten material. In addition to rhenium can significantly reduce the tungsten material of the plastic - brittle transition temperature, the other alloying elements to reduce the plastic - brittle transition temperature have little effect (see metal strengthening)