Nuclear Application of Tungsten Tantalum Alloy

Due to its high density, high melting point, corrosion resistance, and weldability, tungsten-rhenium alloy materials make it a plasma-facing material in nuclear fusion reactors, and it is a very important material for plasma materials in nuclear fusion reactors. It is related to the stability of the plasma in the reactor, the first wall structural materials and components from plasma bombardment and other issues.

In the manufacturing process of tungsten tantalum alloy, the atomic radius of tantalum is 53% larger than that of tungsten. Therefore, when the alloy is displaced, the gap between atoms is larger and it is difficult to reach a very high density. After the ordinary mixing method and vacuum sintering, the porosity of the slab is still high, and the slab density can hardly meet the requirement of more than 98%. Therefore, it is not appropriate to use traditional mixing and sintering methods to manufacture tungsten Tantalum Alloys for nuclear reactors. High quality materials can only be produced in bulk by foreign companies for the time being.

In recent years, with the improvement of smelting technology, some domestic scholars have put forward new ideas.

Step 1. The tungsten powder with the average particle size of 3 um ~ 8 mu m and the tantalum powder with the average particle size of 5 um to 8 m are placed in a row star mill according to the mass ratio of 9.5 to 0.5, and the free ethanol is used as the ball milling medium. The high energy ball milling 3H to 5h under the condition of the vacuum degree is not greater than 0.1Pa and the speed is 150r/min to 225r/min, and the tungsten tantalum is obtained.

Step 2. The tungsten tantalum mixed powder in step 1 is pressed and formed by the cold isostatic press. The blank of the tungsten tantalum alloy plate is obtained. The pressure of the pressing is 150MPa to 300MPa, and the holding time is 1min to 5min.

Step 3. The tungsten tantalum alloy slab was placed in a vacuum hot pressing sintering furnace. The temperature of the vacuum hot pressing sintering furnace was heated at the pressure of 30MPa to 45MPa and the heating rate was 10 ℃ /min ~ 30 ℃ /min, and the temperature in the furnace was raised to 2000 to 2200 ℃ to 6h, and the tungsten tantalum alloy slab was obtained with the cooling of the furnace.

Step 4. The surface of the tungsten tantalum alloy slab is polished and cut to the desired size to obtain the tungsten functional tantalum alloy plate.

The above steps mix the tungsten powder and tantalum powder with smaller size by high energy ball milling, so that the blank composition of the later press is uniform and the vacuum high temperature sintering is used to ensure the final microstructure of the functional material tungsten tantalum alloy plate is uniform, the grain is fine and the density is high, which meets the standard of functional materials for nuclear use.

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