Causes of molybdenum alloy doping rare earth elements
Molybdenum alloy, generally refers to the non-ferrous alloy composed of molybdenum matrix and other elements, has good high temperature strength, low temperature plasticity, thermal conductivity, electrical conductivity and corrosion resistance, as well as low expansion coefficient and other characteristics, widely used in heating elements, radiation shielding materials, forging mold and sputtering layer materials. The added alloying elements include titanium, zirconium, hafnium, tungsten and rare earth elements.
The results show that the main reasons for molybdenum alloy doping rare earth elements are as follows: 1) it is beneficial to refine grain, purify grain boundaries, improve the bending resistance and room temperature toughness of the alloy; 2) Compared with pure molybdenum, rare earth oxide doped molybdenum alloy has higher recrystallization temperature and room temperature strength, and has better droop resistance at high temperature; 3) In a certain range, the strength and recrystallization temperature of molybdenum alloy prepared will be higher with the increase of rare earth oxide content; 4) Molybdenum alloys containing rare earth materials have excellent creep resistance and ductility.
However, the following problems exist in the production and use of rare earth oxide doped molybdenum alloys: 1) The size of the second phase particles is difficult to control; 2) The grain refinement effect of molybdenum alloy is not obvious; 3) The processing quality and service life of products are low; 4) Poor microstructure stability at high temperature; 5) It is easy to introduce impurities in the production process, thus reducing the quality of products.
In order to effectively solve the above problems, researchers proposed a new preparation method of rare earth oxide molybdenum alloy. The specific steps are as follows: 1) Reducing rare earth ammonium diamolybdate with hydrogen to nano rare earth oxide doped molybdenum alloy powder; 2) The alloy powder is pressed into molybdenum slab by cold isostatic pressing, then sintered, forged, and then crossed rolling; 3) After the plate is rolled, the product is annealed and cold rolled into molybdenum plate. After the molybdenum plate is washed by alkali and annealed, the required product can be obtained.
The advantages of the production technology are simple process, can effectively control the size of rare earth oxide particles in the molybdenum plate, and uniform distribution, effectively avoid crack propagation and damage in the process of processing and application, so as to improve the product yield and service life.
