The study of heat-resistant titanium alloy is one of the most important directions in the field of titanium alloy. It is mainly used in the manufacture of the disc, blade and casing of the compressor and fan of the aeroengine. Instead of steel or superalloy, it can significantly reduce the weight of the engine and improve the thrust-weight ratio of the engine. The research on heat-resistant titanium alloys at home and abroad mainly includes two aspects, one is the near-α alloy of Ti-Al-SN-Zr-Mo-Si series, and the other is Ti-Al intermetallic compound alloy. The traditional Ti-Al-Sn-Zr-Mo-Si heat-resistant titanium alloys represented by Ti-1100, IMI834 and Ti60 alloys are relatively mature at present, and their Al element content generally does not exceed 7wt. %. Related alloys have been applied in aero engines, but the highest operating temperature of such alloys is 600℃. More than 600℃ alloy thermal strength will not be able to meet the use. Although Ti-Al intermediate compound alloy can be used at up to 700℃, due to its high Al content, generally more than 20wt. %, the alloy has low plasticity, poor processing performance and high manufacturing cost. Therefore, there is no heat-resistant titanium alloy with obvious processing and performance advantages that can be used for a long time at 650℃.
Compared with the traditional Ti-Al-Sn-Zr-Mo-Si heat-resistant titanium alloy, the heat-resistant titanium alloy of the invention appropriately improves the content of Al element, and the increase of the content of Al element can improve the phase transition point of titanium alloy, reduce the content of residual β phase, reduce the diffusion during the high temperature creep process of titanium alloy, and improve the high temperature creep resistance of titanium alloy. At the same time, the increase of Al content makes more Al2O3 protective film with stable protective effect generated on the surface of titanium alloy under high temperature conditions, and improves the surface oxidation resistance of heat-resistant titanium alloy. Although the increase of Al element content may generate more Ti3Al ordered phase and reduce the plasticity of titanium alloy, the formation of Ti3Al ordered phase can be effectively controlled within the range of Al element content in the invention, so that its adverse effects can be effectively controlled. At the same time, combining with the toughening effect of other elements, the titanium alloy can have better plasticity. If the content of Al element is higher than the content range of the invention, the plasticity of the titanium alloy will be sharply reduced.
