Abstract To explore novel alloy possessing both corrosion resistance and sufficient plasticity to meet various functionality requirements in severe corrosion working environment, in this study, a new Fe-Cr-Ni based alloy with gradually changing composition was synthesized by directed energy deposition with pre-mixed elemental powder. A thin wall sample was fabricated from bottom to top layer by layer following four composition designs (Fe-16Cr-8Ni, Fe-14Cr-16Ni, Fe-12Cr-23Ni, Fe-9Cr-28Ni) to achieve the transition from ferritic phase to austenite phase. The elemental powders used in this research were characterized to analyze the shape and size distribution. The mixing enthalpy for the three elements was studied since it can impact on the deposits homogeneity. Different material characterizations were performed to examine the alloy properties. Microscopic metallography of sample was acquired to analyze the microstructure. Energy dispersive spectroscopy (EDS) analysis examined the composition in the sample. A particle size optimization idea was introduced to keep the original mixing composition. Then Vickers hardness test was done to observe the gradually changing hardness profile. Finally, the phase identification was investigated by X-ray diffraction (XRD). The results indicate that with the increasing Ni and decreasing Cr content, the Vickers hardness numbers (VHN) tend to decrease gradually. The microstructure of regions with 8% and 16% of Ni is mainly the lathy and acicular morphologies, while standard austenite morphology, cells and dendrites, were observed in the regions with 23% and 28% Ni. The XRD pattern can basically verify the metallography observation.

中文翻译：

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定向能量沉积新的 Fe-Cr-Ni 合金，其成分逐渐变化，元素粉末混合物和制造过程中的粒度效应

摘要 为探索兼具耐蚀性和足够塑性以满足严酷腐蚀工作环境中各种功能要求的新型合金，本研究采用定向能量沉积和预混合的方法合成了一种成分逐渐变化的新型 Fe-Cr-Ni 基合金。元素粉末。按照四种成分设计（Fe-16Cr-8Ni、Fe-14Cr-16Ni、Fe-12Cr-23Ni、Fe-9Cr-28Ni）从底部到顶部逐层制造薄壁样品，以实现从铁素体相到奥氏体相。对本研究中使用的元素粉末进行表征以分析其形状和尺寸分布。研究了三种元素的混合焓，因为它会影响沉积物的均匀性。进行了不同的材料表征以检查合金性能。获得样品的显微金相以分析显微组织。能量色散光谱 (EDS) 分析检查了样品中的成分。引入了粒度优化思想以保持原始混合成分。然后进行维氏硬度测试以观察逐渐变化的硬度分布。最后，通过X射线衍射（XRD）研究相识别。结果表明，随着Ni含量的增加和Cr含量的降低，维氏硬度值（VHN）有逐渐降低的趋势。Ni 含量为 8% 和 16% 的区域的显微组织主要是板条状和针状形貌，而在 Ni 含量为 23% 和 28% 的区域中观察到标准奥氏体形貌、细胞和枝晶。XRD图基本可以验证金相观察。