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Why don't domestic Aeroengine Blades use tungsten with high temperature resistance? Instead, rhenium without rare performance is used

  • Mosten
  • 18 June

First of all, it should be understood that the working environment of turbine blade in aeroengine is high temperature (above 1000 ℃), high pressure (above 100MPa), and strong centrifugal force. In addition, the blade should work stably in this environment, and it should not creep or damage. This requires high temperature resistance and creep resistance of the materials used for blades.

It should be noted that the turbine blade materials of advanced aeroengine are all single crystal high temperature resistant alloy, rather than a fixed element composition. The basic elements of tms-75 third generation single crystal high temperature resistant alloy in Japan are nickel, molybdenum, titanium, rhenium, tungsten, chromium, etc., which also contain tungsten. In addition, tungsten is contained in the third generation dd409 single crystal high temperature resistant alloy made in China. In fact, in the early days, when the engine blades were mainly made of deformed superalloys, they still contained tungsten. It can only be said that the contents and types of elements in single crystal leaves vary from country to country. In fact, the addition of tungsten to single crystal superalloy can improve the solid solution strengthening effect, but the content is not as high as rhenium.

Let's first look at the specific properties of "tungsten and rhenium". The melting point of tungsten is the highest among all metals (3422 ℃), but it is easy to react with oxygen at high temperature. In addition, tungsten will also generate Huawei gas at high temperature. Rhenium, whose melting point (3186 ℃) is second only to tungsten and carbon, is relatively stable at high temperature, and its tensile strength is as high as 1172mpa. Rhenium will not expand or shrink when it is converted to high temperature or quench. That is to say, in the process of aeroengine from stop to operation, when the temperature reaches over 1000 ℃ from normal temperature, the engine blades containing rhenium will not deform. This characteristic is very suitable for aeroengine.

The blades of aeroengine are not all made of metal rhenium, and the amount of rhenium in the blades is between 2% and 6%. It is said that the purpose of adding rhenium in the blades is to improve the creep resistance, high temperature resistance and oxidation resistance of single crystal alloy. The results show that rhenium can effectively improve the creep resistance of the alloy.

In fact, tungsten is also used in Aeroengine Blades, but its content is not as high as rhenium, and its application scope is not as wide as rhenium. By. There are two main manufacturing methods of single crystal superalloy blades: first, the single crystal blades are made by directional solidification; second, the single crystal blades are made by high energy beam welding equipment. As for the first method, the alloy must be melted completely before directional solidification. It is also said that the melting point of tungsten is more than 3400 ℃, while that of other rare elements is not so high, which is nearly 300 ℃. So at this temperature after tungsten melting, will it affect other rare metal elements. However, since tungsten is contained in the third generation single crystal superalloy made in China and the third generation single crystal superalloy made in Japan, a series of problems have been solved.

However, tungsten is not rare compared with rhenium, and the focus of aviation is not on tungsten. But the fact tells us that tungsten is still present in Aeroengine Blades.

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molybdenum