Steiner Petrovič Darja, Donik Črtomir, Paulin Irena, Godec Matjaž, Vončina Maja, Petrun Martin
Institute of Metals and Technology, Lepi Pot 11, 1000 Ljubljana, Slovenia.
Faculty of Natural Sciences and Engineering, University of Ljubljana, Aškerčeva 12, 1000 Ljubljana, Slovenia.
Materials (Basel). 2023 Jun 7;16(12):4229. doi: 10.3390/ma16124229.
Lab-scale investigations on the processing of small powder volumes are of special importance for applications in additive manufacturing (AM) techniques. Due to the technological importance of high-silicon electrical steel, and the increasing need for optimal near-net-shape AM processing, the aim of this study was to investigate the thermal behavior of a high-alloy Fe-Si powder for AM. An Fe-6.5wt%Si spherical powder was characterized using chemical, metallographic, and thermal analyses. Before thermal processing, the surface oxidation of the as-received powder particles was observed by metallography and confirmed by microanalysis (FE-SEM/EDS). The melting, as well as the solidification behavior of the powder, was evaluated using differential scanning calorimetry (DSC). Due to the remelting of the powder, a significant loss of silicon occurred. The morphology and microstructure analyses of the solidified Fe-6.5wt%Si revealed the formation of needle-shaped eutectics in a ferrite matrix. The presence of a high-temperature phase of silica was confirmed by the Scheil-Gulliver solidification model for the ternary model Fe-6.5wt%Si-1.0wt%O alloy. In contrast, for the binary model Fe-6.5wt%Si alloy, thermodynamic calculations predict the solidification exclusively with the precipitation of b.c.c. ferrite. The presence of high-temperature eutectics of silica in the microstructure is a significant weakness for the efficiency of the magnetization processes of soft magnetic materials from the Fe-Si alloy system.
对于增材制造（AM）技术中的应用而言，对少量粉末进行实验室规模的研究具有特殊重要性。由于高硅电工钢的技术重要性，以及对优化近净形增材制造工艺的需求不断增加，本研究的目的是研究用于增材制造的高合金Fe-Si粉末的热行为。使用化学、金相和热分析对Fe-6.5wt%Si球形粉末进行了表征。在热加工之前，通过金相观察了原样粉末颗粒的表面氧化情况，并通过微量分析（FE-SEM/EDS）进行了确认。使用差示扫描量热法（DSC）评估了粉末的熔化以及凝固行为。由于粉末的重熔，硅发生了显著损失。对凝固后的Fe-6.5wt%Si进行的形貌和微观结构分析表明，在铁素体基体中形成了针状共晶。通过三元模型Fe-6.5wt%Si-1.0wt%O合金的Scheil-Gulliver凝固模型证实了二氧化硅高温相的存在。相比之下，对于二元模型Fe-6.5wt%Si合金，热力学计算预测其凝固仅伴随体心立方铁素体的析出。微观结构中二氧化硅高温共晶的存在对于Fe-Si合金体系软磁材料磁化过程的效率而言是一个显著弱点。
