An aluminum-tungsten-niobium three-element master alloy with a composition of 25 ~ 40wt% W, 20 ~ 35wt% Nb, 0 ~ 0.3wt% trace elements, and a margin of Al. The invention also discloses a method for preparing a modified master alloy and a method for preparing a high Nb-Ti-Al intermetallic compound ingot by using the master alloy. Using the present invention can be avoided in the process of intermetallic compound melting due to metal elemental melting inconsistent melting current unstable phenomenon, improve the stability of the melting process and effectively reduce the high melting point of refractory elements niobium, tungsten segregation defects of severe high density inclusion probability, so the invention and application of intermediate alloy, The composition and uniformity of Ti-Al intermetallic compound with high melting point are guaranteed.
In the aspect of intermetallic compound, domestic and foreign researchers vigorously promote a high Nb content high temperature titanium aluminum alloy composition, microstructure, performance, preparation process and application technology compared with the conventional titanium aluminum alloy, its use temperature increased 60 ~ 100°C, strength is 300 ~ 500MPa. Its strength index is similar to that of ordinary deformed nickel-based superalloy used for turbine disk, and its specific gravity is about half of that. Its oxidation resistance is much better than ordinary titanium aluminum alloy, and the oxidation resistance of the best nickel-based superalloy is similar.
These intermetallic compounds highlight high Nb and low Al. The basic composition characteristics are as follows: By weight percentage, Nb:10.55 ~ 30wt%; A1:28.33 ~ 30 wt %; Ff :0.87 ~ 8.65wt%, allowance titanium. By increasing the melting point of the alloy, reducing the expansion and stacking fault energy, increasing the creep property, promoting the twinning deformation and improving the stability of the high-temperature structure, the purpose of increasing the service temperature is to add a large amount of Nb element with high melting point. Adding a certain amount of W element to the alloy can increase the toughness and brittleness transition temperature of the alloy, which can make the room temperature strength higher and have a certain shape.
The aluminum-tungsten-niobium three-element master alloy and its preparation method in the above technical scheme are adopted. Compared with the existing raw materials which directly add metal W and Nb elements, the melting point of the master alloy used in the invention is about 1500 ~ 1600°C, which is similar to the melting point of titanium sponge (1670°C). Its far below metal elemental Nb (2467 °C) and W (3370 °C), melting point, avoided in the process of intermetallic compound melting due to metal elemental melting inconsistent melting current unstable phenomenon, improve the stability of the melting process and effectively reduce the high melting point of refractory elements Nb, W segregation seriously high density inclusion defects of probability, Therefore, the invention and application of the master alloy can ensure the composition and uniformity of the intermetallic compound of titanium aluminum with high melting point.
