Molybdenum-niobium alloy plate target material has the characteristics of high melting point, high temperature strength and high temperature toughness, thermal resistance and thermal conductivity, and small coefficient of thermal expansion. Adding a certain proportion of niobium element in molybdenum can increase or expand the LCD pixel by more than two times, so that the display screen with high resolution, high information capacity and high resolution capability has been breakthrough development.
Molybdenum niobium alloy elements like molybdenum and niobium is bigger, the weight difference between elements and different grain size organization, molybdenum elements and niobium elements atomic radius difference is small, so in the process of alloying niobium replacement molybdenum atom molybdenum atoms surrounding pressure, niobium atoms around and point Chen distortion is extremely easily by the control force, at the same time, the internal stress of this point distortion Chen sex is very big, Therefore, in the alloying process, it is easy to produce large alloy deflection, poor grain structure fusion, so that the performance of the alloy is extremely unstable and brittle, resulting in extreme difficulties in the later hot working process. It is very difficult to obtain arbitrary calendering and drawing alloy. In order to solve the production process problem, the inventor mainly adopts three different alloying production methods to compare and find the correct and feasible processing technology. Scheme 1: Using electron beam furnace melting method, molybdenum strip or molybdenum sheet is added with a certain proportion of niobium strip or niobium sheet, which is tied into electrodes and melted at high temperature, and then processed by secondary melting ingot into alloy billet. Scheme 2: Using vacuum sintering, molybdenum niobium alloy powder is pressed into forming embryo shape, through high temperature vacuum furnace sintering into alloy billet, and later processing finished products. Scheme 3: The synthetic alloy powder is made by isostatic pressing, and the alloy billet is made by hydrogen protection firing in medium frequency and high temperature furnace, and then the later processing is carried out.
After comparison, the first scheme makes the alloying process of alloy billet ingot extremely non-uniform.
The niobium atom replaces molybdenum atom to overcome the resistance diffusion, the grain expands, the irregular shape is difficult to carry on the late thermal processing. The second kind of alloy lacks gas catalytic reduction, which is not conducive to displacement and fusion during melting, and the overall uniform composition is not obtained. The properties of the alloy are very unstable, and the alloy becomes brittle and easy to fracture along grain boundaries, irregular cracks appear, and the subsequent hot working plasticity is very poor.
