Li Xiaoshuang, Zweiacker Kai, Grolimund Daniel, Ferreira Sanchez Dario, Spierings Adriaan B, Leinenbach Christian, Wegener Konrad
Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
Institute of Machine Tools and Manufacturing, ETH Zurich, Leonhardstrasse 21, CH-8092 Zurich, Switzerland.
Materials (Basel). 2020 May 10;13(9):2192. doi: 10.3390/ma13092192.
Laser beam-based deposition methods such as laser cladding or additive manufacturing of metals promises improved properties, performance, and reliability of the materials and therefore rely heavily on understanding the relationship between chemical composition, rapid solidification processing conditions, and resulting microstructural features. In this work, the phase formation of four Ni-Cr-Si alloys was studied as a function of cooling rate and chemical composition using a liquid droplet rapid solidification technique. Post mortem x-ray diffraction, scanning electron microscopy, and in situ synchrotron microbeam X-ray diffraction shows the present and evolution of the rapidly solidified microstructures. Furthermore, the obtained results were compared to standard laser deposition tests. In situ microbeam diffraction revealed that due to rapid cooling and an increasing amount of Cr and Si, metastable high-temperature silicides remain in the final microstructure. Due to more sluggish interface kinetics of intermetallic compounds than that of disorder solid solution, an anomalous eutectic structure becomes dominant over the regular lamellar microstructure at high cooling rates. The rapid solidification experiments produced a microstructure similar to the one generated in laser coating thus confirming that this rapid solidification test allows a rapid pre-screening of alloys suitable for laser beam-based processing techniques.
基于激光束的沉积方法，如激光熔覆或金属增材制造，有望改善材料的性能、性能和可靠性，因此严重依赖于理解化学成分、快速凝固加工条件和由此产生的微观结构特征之间的关系。在这项工作中，使用液滴快速凝固技术研究了四种镍铬硅合金的相形成与冷却速率和化学成分的关系。事后X射线衍射、扫描电子显微镜和原位同步加速器微束X射线衍射显示了快速凝固微观结构的存在和演变。此外，将所得结果与标准激光沉积试验进行了比较。原位微束衍射表明，由于快速冷却以及Cr和Si含量的增加，亚稳态高温硅化物保留在最终微观结构中。由于金属间化合物的界面动力学比无序固溶体的界面动力学更缓慢，在高冷却速率下，异常共晶结构比规则的层状微观结构更占主导地位。快速凝固实验产生的微观结构与激光涂层中产生的微观结构相似，从而证实了这种快速凝固试验能够对适用于基于激光束的加工技术的合金进行快速预筛选。
