In the smelting method of Nb-TiAl based alloy, sponge titanium, niobium titanium alloy and aluminum bean are used as raw materials, which are pressed and welded to form consumable electrode, and then melted in vacuum consumable arc furnace to obtain high Nb-TiAl based alloy. The electrode block is prepared by combining mixing material with cloth. High Nb-TiAl alloy with uniform composition and no cracks can be obtained by three times melting in vacuum consumable arc melting furnace and slow cooling by burying sand or annealing. The method of the invention has the advantages of simple and strong operability, and can be used to produce a high Nb-TiAl base alloy with uniform composition, no segregation and inclusion.
Titanium aluminum alloy has the advantages of light weight, high specific strength, corrosion resistance, wear resistance, high temperature resistance and oxidation resistance, and has excellent mechanical properties at room temperature and high temperature. It has become one of the excellent candidates for high temperature structural materials in the fields of contemporary aerospace, weapons and civil industry, and has important engineering application potential.
High Nb alloying has brought the development of TiAl alloy to a new stage. The yield strength at room temperature can reach 800MPa, and the strength at 760℃ can reach 550MPa. At the same time, the original tensile elongation at room temperature is maintained, especially the oxidation resistance of the alloy is greatly improved. Due to the difference of melting point and density of the constituent elements of TiAl alloy and the difference of non-equilibrium solidification segregation coefficient, segregation is inevitable in the ingot. However, the high content of Nb in high Nb-TiAl base alloy is easy to cause microscopic segregation or inclusion. According to the present research results, vacuum consumable arc melting is still a suitable melting method for TiAl based alloys. However, defects such as non-frit, segregation and cracking are easy to be formed in the production of high Nb-TiAl based alloy by traditional technology.
The melting method of Nb-TiAl base alloy is characterized by using titanium sponge, niobium titanium alloy, aluminum bean and intermediate alloy as raw materials, pressing and welding to form a consumable electrode, and melting in a vacuum consumable arc furnace to obtain high Nb-TiAl base alloy. Among them, the intermediate alloy is chromium metal, aluminum vanadium alloy, titanium diboride, tungsten powder, yttrium metal one or several.
