Moravcikova-Gouvea Larissa, Moravcik Igor, Pouchly Vaclav, Kovacova Zuzana, Kitzmantel Michael, Neubauer Erich, Dlouhy Ivo
Institute of Materials Science and Engineering, Brno University of Technology, Technicka 2896/2, 61669 Brno, Czech Republic.
Central European Institute of Technology (CEITEC), Purkynova 123, 61200 Brno, Czech Republic.
Materials (Basel). 2021 Oct 3;14(19):5796. doi: 10.3390/ma14195796.
This paper reports the microstructural evolution and mechanical properties of a low-density AlNbTaTiVZr refractory high-entropy alloy (RHEA) prepared by means of a combination of mechanical alloying and spark plasma sintering (SPS). Prior to sintering, the morphology, chemical homogeneity and crystal structures of the powders were thoroughly investigated by varying the milling times to find optimal conditions for densification. The sintered bulk RHEAs were produced with diverse feedstock powder conditions. The microstructural development of the materials was analyzed in terms of phase composition and constitution, chemical homogeneity, and crystallographic properties. Hardness and elastic constants also were measured. The calculation of phase diagrams (CALPHAD) was performed to predict the phase changes in the alloy, and the results were compared with the experiments. Milling time seems to play a significant role in the contamination level of the sintered materials. Even though a protective atmosphere was used in the entire manufacturing process, carbide formation was detected in the sintered bulks as early as after 3 h of powder milling. Oxides were observed after 30 h due to wear of the high-carbon steel milling media and SPS consolidation. Ten hours of milling seems sufficient for achieving an optimal equilibrium between microstructural homogeneity and refinement, high hardness and minimal contamination.
本文报道了通过机械合金化和放电等离子烧结（SPS）相结合的方法制备的低密度AlNbTaTiVZr难熔高熵合金（RHEA）的微观结构演变和力学性能。在烧结之前，通过改变球磨时间对粉末的形态、化学均匀性和晶体结构进行了深入研究，以找到致密化的最佳条件。在不同的原料粉末条件下制备了烧结块状RHEA。从相组成和结构、化学均匀性以及晶体学性质方面分析了材料的微观结构演变。还测量了硬度和弹性常数。进行了相图计算（CALPHAD）以预测合金中的相变，并将结果与实验进行了比较。球磨时间似乎对烧结材料的污染程度有显著影响。尽管在整个制造过程中使用了保护气氛，但早在粉末球磨3小时后，在烧结块中就检测到了碳化物的形成。由于高碳钢球磨介质的磨损和SPS固结，在30小时后观察到了氧化物。10小时的球磨似乎足以在微观结构均匀性和细化、高硬度和最小污染之间实现最佳平衡。
