The use temperature of tungsten materials is high, and the solid solution strengthening method alone has little effect on improving the high temperature strength of tungsten. However, dispersion (or precipitation) strengthening on the basis of solid solution strengthening can greatly improve the high temperature strength, and the strengthening effect of ThO2 and precipitated HfC dispersed particles is the best. Both W-Hf-C series and W-ThO2 series alloys have high high temperature strength and creep strength at around 1900°C. For tungsten alloys used below the recrystallization temperature, it is an effective way to strengthen it by adopting warm work hardening to produce strain strengthening. For example, the fine tungsten wire has high tensile strength, the total processing deformation rate is 99.999%, the diameter of the fine tungsten wire is 0.015 mm, and the tensile strength can reach 438kg·N/mm2 at room temperature.
Among refractory metals, tungsten and tungsten alloys have the highest plastic-brittle transition temperature. The plasticity-brittle transition temperature of sintered and smelted polycrystalline tungsten materials is between 150 and 450°C, which causes difficulties in processing and use, while single crystal tungsten is lower than room temperature. The interstitial impurities, microstructure and alloying elements in tungsten materials, as well as plastic processing and surface conditions, have a great influence on the plasticity-brittle transition temperature of tungsten materials. Except for rhenium, which can significantly reduce the plasticity-brittle transition temperature of tungsten materials, other alloying elements have little effect on reducing the plasticity-brittleness transition temperature.
Tungsten has poor oxidation resistance, and its oxidation characteristics are similar to those of molybdenum. Tungsten trioxide volatilizes above 1000°C, resulting in "catastrophic" oxidation. Therefore, tungsten materials must be protected by vacuum or inert atmosphere when used at high temperature. If used in high temperature oxidizing atmosphere, protective coating must be added.