Krawczyk Jacek, Bogdanowicz Włodzimierz
Institute of Materials Engineering, University of Silesia in Katowice, 1a 75 Pułku Piechoty St., 41-500 Chorzów, Poland.
Materials (Basel). 2022 Jan 20;15(3):781. doi: 10.3390/ma15030781.
The dendritic structure and the distribution of the γ'-phase lattice parameter (a) along selected lines of the longitudinal section in a model single-crystalline blade made of CMSX-4 nickel-based superalloy were studied. It was established that there is a correlation between the value of the a and the predomination of initial or ending fragments of the secondary dendrite arms. It is most noticed for the areas where the dendrite growth conditions are similar to steady. They are located in the center and near the root's selector extension (SE) area. The correlation has been related to the dendritic segregation mechanism. It was shown that in the single-crystalline blades obtained by the directional crystallization using a spiral selector, the "walls" of the primary dendrite arms that grow at a low angle to the blade axis are created. It was found for the first time that the value of the lattice parameter a is decreased near such "walls". Additionally, it was found that competitive growth of the dendrites may occur at a distance of even several millimeters from the bottom surface of the root. The first-time applied X-ray diffraction measurements of a made in a single-pass along the line allow the analysis of the dendritic segregation in the whole blade cast.
研究了由CMSX-4镍基高温合金制成的模型单晶叶片纵向截面中枝晶结构以及γ'相晶格参数（a）沿选定线的分布。结果表明，a值与二次枝晶臂起始或末端片段的占比之间存在相关性。在枝晶生长条件类似于稳态的区域最为明显。它们位于叶片中心和根部选晶器延伸区（SE）附近。这种相关性与枝晶偏析机制有关。结果表明，在使用螺旋选晶器通过定向凝固获得的单晶叶片中，形成了与叶片轴线成小角度生长的一次枝晶臂的“壁”。首次发现，在这种“壁”附近晶格参数a的值会减小。此外，还发现枝晶的竞争性生长可能发生在距根部底面甚至几毫米的距离处。首次沿直线单次进行的a的X射线衍射测量允许对整个叶片铸件中的枝晶偏析进行分析。
