The preparation method of polycrystalline raw material bar for molybdenum-niobium alloy single crystal is as follows: FMO-1 powder and FNB-1 powder are mixed by mixer and pressed into billet, and the billet is sintered into sintered strip at high temperature; The sintered bars were welded into electrodes, and the electrodes were fused twice in an electron beam melting furnace to make molybdenum-niobium alloy ingots. After machining, the machined molybdenum-niobium alloy ingots were directly extrusion-processed into molybdenum-niobium alloy polycrystalline bars in a hydraulic press, and the molybdenum-niobium alloy polycrystalline bars were straightening and sandblasted. Molybdenum-niobium alloy polycrystalline bar was forged by heating under argon atmosphere, and then the polycrystalline bar for molybdenum-niobium alloy single crystal was prepared by centerless grinding. The invention has the advantages of simple process and low cost, the total content of impurity elements in the prepared polycrystalline raw material bar is not more than 500ppm, the bar is uniform in structure, no cracks or pores and other defects, and the straightness of the polycrystalline raw material bar is not more than 1mm/m.
Electron East suspension region melting is a classical method to prepare refractory metal and its alloy single crystal materials. The requirements of the method for the preparation of alloy single crystal polycrystalline raw material bar are: l) in the polycrystalline raw material bar.
The total content of impurity elements should not exceed 500ppm; 2) The structure of the polycrystalline raw material bar is uniform, without cracks or pores and other defects; 3) The straightness of the polycrystalline raw material bar shall not be greater than LMM /m.
It is difficult for molybdenum-miobium alloy sintered bar prepared by general powder metallurgy method to meet the requirements of polycrystalline raw material bar for molybdenum-niobium alloy single crystal prepared by electron suspension region melting. For example, the total content of gaseous impurities such as oxygen, hydrogen, nitrogen and carbon in the alloy sintered rod prepared by powder metallurgy method exceeds 1500ppm, and there are certain pores and other defects in the polycrystalline raw material bar, which is very unfavorable to the subsequent smelting of alloy single crystal in the electron east suspension zone.
At present, there are no published reports on the fabrication methods of high quality polycrystalline raw materials for molybdenum-niobium alloy single crystal. Therefore, in order to prepare molybdenum-niobium alloy single crystal to meet the requirements, it is urgent to form a set of economic and feasible processing technology for the preparation of molybdenum-niobium alloy single crystal polycrystalline raw material bar.
