In an effort to reduce energy consumption and expensive Co content, herein we report the effects of Co content on microstructure and microhardness of widely studied AlCo_xCrFeNi high-entropy alloys produced by cost-efficient aluminothermic self-propagating high-temperature synthesis (SHS) method. Accordingly, the feasibility of SHS technique in the production of AlCo_xCrFeNi master high-entropy alloys was discussed. In order to investigate the effect of further casting, the SHS alloys were also subjected to vacuum arc melting/suction casting process. Prior to SHS; phase diagram, raw material amounts and adiabatic temperatures were calculated via thermochemical modelling. The calculated equilibrium phase diagram suggested a full BCC structure over the whole Co range. However, according to XRD results, as-cast alloys consisted of BCC and FCC phases, having microhardness values ranging in between 385 HV and 504 HV, depending on Co content. The increase in Co content, enlarged the grains, altered the spinodal decomposition morphology and led to the formation of dual-phase (FCC + BCC) alloys, which in return had a significant effect on the microhardness values. Overall hardness values were increased due to finer microstructure obtained by suction casting. Also, Widmanstätten plate-like growth of the FCC phase inside the BCC cores was kinetically suppressed due to higher cooling rate. It was concluded that AlCo_xCrFeNi master high-entropy alloys can be successfully produced by SHS method and the attained dual-phase microstructures could be beneficial in tailoring mechanical properties as well as reducing the total cost of the AlCo_xCrFeNi HEAs system in addition to the significant energy reduction obtained via SHS route.

为了减少能耗和昂贵的Co含量，在此我们报告Co含量对由成本效益高的铝热自蔓延高温合成（SHS）生产的广泛研究的AlCo _x CrFeNi高熵合金的组织和显微硬度的影响方法。因此，SHS技术在AlCo _x生产中的可行性讨论了CrFeNi母体高熵合金。为了研究进一步铸造的效果，还对SHS合金进行了真空电弧熔化/吸铸工艺。在SHS之前；通过热化学模型计算相图，原料量和绝热温度。计算出的平衡相图表明在整个Co范围内都有完整的BCC结构。但是，根据XRD结果，铸态合金由BCC和FCC相组成，其显微硬度值取决于Co含量，介于385 HV和504 HV之间。Co含量的增加，晶粒的扩大，改变了旋节线的分解形态，并导致了双相（FCC + BCC）合金的形成，而这反过来又对显微硬度值产生了重大影响。由于通过吸铸获得了更精细的微观结构，总硬度值有所提高。另外，由于冷却速率较高，在动力学上抑制了BCC芯内部FCC相的Widmanstätten板状生长。结论是铝钴可以通过SHS方法成功地生产_x CrFeNi母体高熵合金，获得的双相微结构不仅可以显着降低能耗，而且在调整机械性能以及降低AlCo _x CrFeNi HEA系统的总成本方面也将是有益的通过SHS路线。