A β γ high Nb TiAl alloy with excellent high temperature deformation ability, belongs to the field of metal materials. The alloy is composed of Ti, Al, Nb, B, Y and β phase stable elements (Mn, Cr, Mo, V), which Al content is 40 44AT %, Nb content is 6 10at %, B content is 0.1 0.3at %, Y content is 0.1 0.3at %. The single addition amount of Mn and Cr is 0.5 3.0 AT %, the single addition content of Mo and V is 0 2.0at %, the total addition amount is 1.0 7.0at %, and the allowance is Ti. The microstructure of the cast alloy is mainly composed of γ phase and β phase. The content of α2 phase is less, which is 2.0% ~ 5.0%. The microstructure of the cast alloy is fine and uniform equiaxed crystal. The invention has the advantages that the β -phase stable element is added, the β -phase content is increased, the high temperature deformation ability of the high Nb - γ TiAl alloy is improved, and the β -γ high Nb - TiAl alloy has excellent high temperature deformation ability.
The high Nb γ -tial intermetallic compound increases the melting point and ordering temperature of the alloy, reduces the diffusion coefficient and stacking fault energy, and improves the high temperature strength and oxidation resistance of the alloy. It also takes into account the advantages of low density, simple crystal structure and easy to improve the properties by controlling the microstructure of ordinary γ -tial alloy. Therefore, it is considered to be a new generation of high temperature and light structural materials with the most potential application in the future aerospace industry. However, due to the low plasticity and fracture toughness of high nb γ -tial alloy at room temperature, its hot working performance is poor, which limits its practical application. Obtaining fine and uniform microstructure is the key to improve the room temperature ductility of γ -tial alloy.
At present, the main methods to improve the room temperature plasticity of γ -tial alloy are alloying, heat treatment and hot working (such as forging, rolling). Wu XH,Hu D.Microstructural refinement in cast TiAlalloys by solid state transformations.Scripta Mater,2005; 52:731.) The room temperature plasticity of the alloy is improved by eliminating the brittle B2 phase in the room temperature structure, but the heat treatment process is relatively long, and obvious grain growth phenomenon is easy to occur. Hot-working (Tetsui T,Shindo K,Kobayashi S,Takeyama M.A newlydeveloped TiAl alloy for blades and structural Components. ScriptaMater, 2002; 47:339.) can effectively break the coarse as-cast microstructure and improve its mechanical properties at room temperature, but hot processing requires good deformation ability at high temperature, and the coarse as-cast microstructure of common γ -tial alloy is not conducive to the hot processing of the alloy.
