| Because of its excellent properties, Mo alloy have been widely used in aerospace, atomic energy, electronic, metallurgy, chemical, lighting and glass industries. However, the applications of molybdenum as a structural material are limited by its high DBTT, brittleness and low strength at room temperature.In order to improve the mechanical properties of pure Mo, ultrafine Mo powder and ultrafine composite Mo powers with La/Y were fabricated via sol-spray drying, calcination and subsequent hydrogen reduction process. Phase transition of MoO3 during reduction process was investigated and influence of La/Y on powers was also studied. The ultrafine ODS Mo-alloys with excellent properties were fabricated after sintered at 1890℃during 2 hours. And the effect of La/Y on mechanical properties of Mo-alloy was investigated. The following is the results:1) Rare earth oxides are found in ultrafine Mo powders. With increasing of La/Y, the content of powders is also increased. On the other hand, doped La/Y can refine powders'grain. When content of La/Y is 3%, the dimension of powder' grain is less than 0.1μm, and dimension of pure Mo powder is about 0.5μm under the same technology.2) When content of Y is 2%, the tensile strength of Mo-alloy reach to 620MPa, which higher 60% than pure Mo. Under the same technology, tensile strength of Mo-alloy doped 2% La is 53.5MPa, which means the strengthening effect of Y is better than that of La.3) The second particles containing La/Y can be found in Mo-alloy. The migration of grain boundaries are hindered by these particles, which inhibit grains'growing of Mo. The grains of Mo-alloy is 3～5μm when 2% La/Y add to Mo-alloy... |
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