In the technical field of high temperature structural material plate preparation, the invention relates to a preparation method of high niobium titanium-aluminum base alloy plate. The technical scheme of the invention is that the alloy billet is directly cut from the cast ingot, and after homogenizing heat treatment, it is put into the sandwich type structural envelope, the peeling agent is added between the billet and the envelope, the envelope is heated in a protective atmosphere, and after hot rolling, the envelope is removed to obtain a large size high niobium titanium aluminum base alloy sheet. The invention designs a new process route for preparing high niobium titanium-aluminum base alloy sheet by hot rolling of metallurgical ingot coating, and the process route is simple and economical. Compared with the current common hot isostatic pressing + isothermal forging/isothermal extrusion pretreatment, the process is greatly shortened, which is suitable for industrial large-scale production; Compared with isothermal rolling mill and isothermal forging, the equipment requirements of this method are greatly reduced, and it can be widely used.
Because of its low density, high elastic modulus, high specific strength and excellent oxidation resistance, titanium-aluminum intergeneric compounds can reach 700~900℃, and are considered to be the only candidate materials for the upper limit of Ti alloy and the lower limit of Ni-based superalloys in the aerospace field. Because of the addition of high melting point Nb, the melting point and ordering temperature of the alloy are increased, the stacking fault energy and atomic diffusion are reduced, and the high temperature strength and oxidation resistance of the alloy are improved. Compared with Ni-based superalloys and high-temperature ceramic materials, it has higher strength than Ni-based superalloys, better plasticity and toughness than ceramics, and the use temperature is 60 to 100℃ higher than that of ordinary titanium-aluminum alloy. Therefore, high niobium titanium-aluminum base alloy represents the current research direction of titanium-aluminum base alloy.
Because of its intrinsic brittleness, the machining properties of Ti-Al base alloy are poor at room temperature and high temperature. In particular, the preparation of titanium-aluminum alloy sheet is difficult, which restricts its wide application. Compared with ordinary titanium-aluminum-based alloys, high niobium titanium-aluminum-based alloys require higher thermal processing temperature and smaller thermal processing window. At present, the alloy blanks selected for the preparation of ordinary titanium-aluminum-based alloy and high-niobium titanium-aluminum-based alloy plates need to be preformed by hot isostatic pressing treatment + hot mechanical treatment, which includes multiple near-isothermal envelope forging or envelope hot extrusion, so the process is long and the cost is high.
