Tungsten-rhenium wire
Tungsten rhenium alloy wire (Tungsten rhenium alloy wire for Sapphire) is a kind of tungsten alloy consisting of tungsten and rhenium. The typical concentrations of rhenium in this alloy are 1%, 3%, 5%, 20%, 25% and 26%, etc.
Micro-cracks are often bred on the grain boundary of tungsten and the propagation of these micro-cracks is an important reason for the fracture of tungsten. Twins are easily formed during the deformation process of W-Re alloy, which reduces the dislocation energy of stacking layer and grain boundary impedance of dislocation movement, leading to the increase of dislocation mobility and the improvement of tungsten solution softening. This phenomenon is called "rhenium plasticization effect". In the series of tungsten-rhenium alloys, the plasticization effect of rhenium is obvious when the concentration of rhenium is low, but decreases when the concentration of rhenium is high.
Classified by use:
W-3Re/W-25Re, W-5Re/W-20Re, W-5Re/W-26Re, W/W-26Re,2: W-25Re wire or sapphire W-Re alloy wire for single crystal sapphire binding
Tungsten-rhenium alloys have a series of excellent properties, such as high melting point, high strength, high hardness, high plasticity, high recrystallization temperature, high resistivity, low vapor pressure, low electron escape work and low plastic brittle transition temperature, etc. In addition to the above properties, the low rhenium alloy and the high rhenium alloy wire are matched to form a thermocouple with a high thermoelectric potential value. The relationship between the thermoelectric potential value and temperature of various types of tungsten-rhenium thermocouples Tungsten-rhenium wire for single crystal sapphire binding commonly used model: W-25Re, diameter 0.5mm.
1. The distribution of rhenium in tungsten-rhenium wire is uniform, and the fluctuation range of rhenium content is controlled within 30.15%;
2. The single weight of the blank bar is 3Kg;
3. To diameter 0.39mm, the yield of tungsten-rhenium wire is not less than 75%;
4. The wire diameter of tungsten-rhenium wire is uniform.
There are two ways to make tungsten-rhenium alloy: powder metallurgy and smelting, and powder metallurgy is commonly used in actual production. The powder metallurgy process for producing tungsten-rhenium alloys is as follows:
Preparation of tungsten-rhenium pre-alloying powder → hydrogen reduction → pressing (mold pressing or isostatic pressing)→ sintering (vertical melting sintering or medium frequency induction sintering)→ pressure processing (including extrusion, rolling, rotary forging and wire drawing).
For making tungsten rhenium pre alloy powder is a commonly used method of fixation (tungsten powder mixed with rhenium powder, tungsten trioxide powder mixed with rhenium acid ammonium powder), solid a liquid method (mixed with ammonium nitrate solution rhenium tungsten powder, tungsten trioxide powder mixed with rhenium acid ammonium solution), a liquid (ammonium tungstate solution mixed with rhenium acid ammonium solution by spray drying or other methods for making), etc.
Hydrogen reduced tungsten-rhenium alloy powder can be formed by mechanical pressing, steel die pressing, or isostatic pressing (even density of compaction).The compacted bars can be directly fired by vertical melting or by Cp, N induction by indirect heating. The relative density of tungsten-rhenium alloy bars is 92% ~ 95%.The best quality billet can be obtained by isostatic pressing and medium frequency induction heating sintering, and its uniformity and consistency are the best among all production methods.
Tungsten-rhenium alloy is mainly used as structural material in high temperature field, and has a wide range of applications in electronic technology, nuclear technology, aerospace technology and temperature measurement technology.
At present, there are three aspects that are most widely used:
1. The low rhenium alloy wire is matched with the high rhenium alloy wire to form a thermocouple
2. Low rhenium alloy wire and high rhenium alloy wire match into a thermocouple, wide temperature range (0 ~ 2500C), high thermoelectric potential value, fast response speed, good corrosion resistance, so tungsten-rhenium thermocouple wire is widely used in temperature measuring instruments. It is not only used in vacuum, reducing atmosphere and inert atmosphere, but also used to replace platinum rhodium thermocouple temperature measurement in oxidizing atmosphere when taking anti-oxidation measures to get practical applications.
3. Used for manufacturing single crystal sapphire and binding.
