Tungsten alloy is a broad materials group that includes various types of tungsten alloys and composites. CHEMETAL USA is an innovator at the leading edge of tungsten alloy fabrication. The company is renowned for its advanced manufacturing and machining capabilities, as well as application-oriented expansion and property diversification of tungsten alloy products. CHEMETAL USA’s primary tungsten alloy product types are tungsten heavy metals, tungsten copper, and lanthanated tungsten. Other types of tungsten alloys include tungsten chromium, tungsten rhenium, tungsten cobalt, tungsten aluminum, tantalum tungsten, magnesium tungsten, tungsten silver, and platinum tungsten.
Effects of Heat Treatments on Tungsten Alloy
Heat treatments to the tungsten alloy will follow after the sintering process, which includes quenching, dehydrogenizing, and surface hardening. The heating process is also a dehydrogenizing process to the tungsten alloy. It decreases the hydrogen embrittlement and segregation of impurities including P and S. As a result, the tensile strength, and ductility of tungsten alloys are dramatically improved by heating treatments. In addition, tungsten alloy attains a fine grain size and a homogenous crystallized structure.
The heat treatment of tungsten alloy can significantly enhance the engineering properties. Take the example of heating W 95 tungsten alloy in a medium-frequency induction furnace. The strength and impact toughness will be markedly increased on the condition that the working temperature ranges from 850 to 900 °C and the heating lasts for 40 minutes.
The company has mastered powder metallurgical techniques including solid-state sintering; liquid-phase sintering; and infiltration methods. Sintered elements, including Ni, Fe, Cu, La, and Ce, etc. can be custom composited to greatly enhance tungsten’s physical, chemical, and mechanical properties for specialized applications across a wide range of industries.
Tungsten Heavy Alloy (Heavy Metal, Tungsten Heavy Metal, WHA)
Tungsten heavy alloy, also called “heavy metal” or “tungsten heavy metal,” is the most popular tungsten alloys, often composited with biding additives such as nickel, copper, or iron. Such alloys yield a more malleable microstructure, more ductile and machinable, yet maintaining pure tungsten’s unique properties including high density, high temperature resistance, and high conductivity. As result, tungsten nickel copper and tungsten nickel iron are characterized by their exclusive combination of density, ductility and hardness. They are ideal materials for use in counterweights, radiation shielding parts, and wear resistant components.
|ASTM B 777||Class 1||Class 2||Class 3||Class 4|
|Tungsten Nominal %||90||92.5||95||97|
|Utimate Tensile Strength||ksi||110||110||105||100|
|Yield Strength at 0.2% off-set||ksi||75||75||75||75|
Tungsten nickel iron (WNiFe) has comparatively higher strength and ductility than tungsten nickel copper (WNiCu). However, W-Ni-Fe alloy belongs to magnetic alloy and might slightly interrupt or divert the surrounding magnetic field. Therefore, it is not always the preferable tungsten alloy material in applications such as aerospace and electronic devices. Tungsten nickel copper is non-magnetic and has a better electronic and thermal conductivity, so it is more suitable for components that are required to work under a magnetic environment, such as the contact of high voltage devices and electrodes. More about tungsten heavy alloy properties>>>
Copper-infiltrated Tungsten Alloy (Copper Tungsten Alloy, WCu)
Tungsten copper is an ideal material for use as electrodes for EDM machining and resistance welding, as well as for electronic contacts and thermal management parts for high power and high temperature applications.
|Composition||Density||Electrical Conductivity||CTE||Thermal Conductivity||Hardness||Specific Heat|
|g/cm³||IACS % Min.||10-6 K-1||W/m · K-1||HRB|
|J/g · K|
Copper-infiltrated tungsten alloy combines copper’s excellent electrical and thermal conductivity with tungsten’s high density, hardness, and melting point. The high strength, porous tungsten frame gives copper tungsten EDM electrodes an outstanding wear resistance rate. When infiltrated with tungsten, highly conductive copper also gives EDM electrodes a high material remove rate. Yet another excellent attribute of tungsten copper is its impressive CTE (coefficient of thermal expansion) performance as heat spreaders and heat sinks for integrated electronic devices. Tungsten copper’s CTE range perfectly covers the CTEs of most common semiconductor materials and ceramic substrate materials. More about copper tungsten alloy properties>>>
Lanthanated, Ceriated, Thoriated Tungsten Alloys
Rare earth oxide tungsten alloys, including lanthanated, ceriated, and thoriated tungsten, are exceptional materials for use as electrodes for TIG (tungsten insert gas) welding, resistant welding, and plasma spraying applications.
Oxide Rare Earth Properties And Composition In Tungsten Alloy
|Type of oxides||ThO2||La2O3||CeO2||Y2O3|
|Melting point oC||3050|
|Heat of decomposition. Kj||1227.6||1244.7||(523.4)||1271.1|
|Type of oxides after sintering||ThO2||La2O3||CeO2|
|Reaction with tungsten||Reduction of ThO2|
by W occurs.
forming pure Th.
|Forming tungstate||Forming tungstate|
|Stability of oxides||Lower stability||Higher stability||Reasonable stability at |
the electrode edge
but lower stability
at the tip
|Oxide weight %||0.5 - 3||1 - 3||1 - 3||1 - 3|