Niobium Tungsten Hafnium Superalloy Synthesis Scheme

At present, the highest working temperature of the most mature and widely used niobium tungsten hafnium superalloy in the high temperature field is 1050 ~1150 ℃, which has reached 80%~85% of the melting point of the Ni-based superalloys. In order to meet the service conditions of high temperature strength and room temperature plasticity of spacecraft in the temperature range of 1200 1400 ℃, new super high temperature alloy materials with refractory metal matrix are still being developed in China.

Excessive refractory niobium is a kind of metal element with high melting point (2467 ℃), appropriate density (8.55g/cm³), good room temperature toughness and easy alloying. It is the most promising metal material in the field of ultra-high temperature. The addition of Hafnium and tungsten elements with large atomic size difference and high melting point in Nb can form a single-phase solid solution. The design idea of multi-element solid solution strengthening can improve the high-temperature mechanical properties of Nb-based alloys and maintain good room temperature plasticity of Nb-based solid solution. It can be used as a high temperature aircraft in the range of 1200 ~1400. Temperature structural materials can meet the requirements of high temperature strength and room temperature plastic phase equilibrium. The synthesis scheme of niobium tungsten hafnium superalloy are prepared by the following method:

(1)Niobium Nb with 99.99% purity, tungsten W with 99.99% purity and hafnium Hf with 99.99% purity were obtained according to the composition ratio.

(2)Niobium, tungsten and hafnium are put into a non-consumable vacuum arc furnace, vacuum is pumped to 1 *10^-3 pa~5 *10^-3 pa, high purity argon is filled to 1.01 *105 Pa, and then melted into niobium tungsten hafnium superalloy ingot at 2000 ~2200 ℃.

(3)The niobium tungsten hafnium superalloy ingots prepared above are put into vacuum heat treatment furnace for heat treatment, and the single-phase niobium tungsten hafnium superalloy materials are obtained after holding for 48 hours at 1 *10^-3 3a to 5 *10^-3 3A at 1700 ℃.

Advantages of single-phase niobium tungsten hafnium superalloy materials: On the basis of Nb, applying the principle of multi-element alloying and solid solution strengthening, the high-temperature mechanical properties of single-phase Nb solid solution are improved by adding Hf and W elements which are different from Nb in atomic size and have high melting point, and the good room temperature plasticity of single-phase Nb solid solution is maintained. The density of these alloys is 9.7-10.8g/cm³, which is close to that of Ni-based superalloys (about 8g/cm³), much lower than that of Ir-based superalloys (19-22g/cm³). They have good combination of high temperature strength and room temperature plasticity, and are suitable for high temperature static applications requiring high strength.

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