镍基高温合金铸造叶片表面细化机理的研究

Research on Surface Grain Refinement in Ni Based Superalloy of Turbine Blades

选用K18合金和纯金属镍及不同的面层细化料,通过实验对比研究了镍基高温合金叶片表面晶粒细化机理。结果表明在凝固过程中高温合金中的活性元素与面层涂料中的CoO·Al2O3发生置换反应,生成与基体晶格相近的难熔细小钴颗粒,促进叶片表面形核率的增加,使表面晶粒细化,从而提高叶片表面的抗疲劳性能。

Surface grain refinement of turbine blades in Ni based superalloy K18 were studied by comparison of experimental results in different alloys and mold surface materials. It is found that the Surface grain refinement in turbine blades effectively to improve resistance of blades to fatigue, is attributed to the increase of nucleation induced by generation of Co refractory particulate with similar lattice size to matrix, which occurs when CoO · Al2O3 of refining materials is displaced with active elements of molten superalloy during solidification period.