Preparation method of high-quality niobium-based alloy cast ingot

The invention belongs to the field of niobium-based alloy preparation, and discloses a preparation method of a high-quality niobium-based alloy cast ingot. The preparation method comprises the following steps: firstly, uniformly mixing aluminum powder, niobium pentoxide, zirconium dioxide, a heat generating agent and a slag former, and preparing an aluminum-niobium-zirconium alloy cast ingot by adopting a vacuum aluminothermic reduction method; smelting and purifying by adopting a vacuum electron beam horizontal furnace, and shearing to obtain a centimeter-level block; and finally, a plasma smelting furnace is adopted for further smelting, and the Nb-1Zr alloy cast ingot meeting the national standard is obtained. The process principle and the preparation method disclosed by the invention are simple, and the Nb-1Zr alloy is prepared in a mode of combining vacuum aluminothermic reduction reaction, vacuum electron beam melting and plasma melting for the first time; the problems of high cost, low production effic