In this study, the feasibility of the synthesis of AlCoCrFeNiMo (0.5 < x < 3, y = 0.5,1) alloys via cost and energy efficient thermochemical modelling assisted (FactSage™) aluminothermic self-propagating high-temperature synthesis (SHS) method was investigated. In addition, selected SHS alloys were also suction-casted into a bar shape by using a vacuum arc melter and the microstructural changes and oxidation behaviour of selected alloys were investigated. The characterization results demonstrated that AlCoCrFeNiMo (0.5 < x < 3, y = 0.5,1) master alloys can be successfully synthesized via thermochemical modelling assisted SHS method with a substantial composition control. The microstructures of the SHS alloys were found to comprise of the FCC-A1, BCC (A2, B2) and σ phases with varying fractions depending on the composition. Increasing Al content was found to increase the hardness of the alloys from 278 HV to 829 HV for the AlCoCrFeNiMo system. For AlCoCrFeNiMo system, on the other hand, it had an increasing effect from Al0.5 to Al1.0 (from 659 HV to 903 HV) initially and then decreased the hardness to the levels of 773 HV with the further addition of Al. Suction-cast alloys exhibited rather similar microstructures with similar phase constituents and hardness values. As a general trend primer B2 phase fraction was increased due to higher cooling rate. Oxidation studies revealed that the Al3.0Mo0.5 alloy, which has higher B2 content (919 HV), exhibited better oxidation resistance after 100 h of exposure to air at 800 °C. Postulated scaling mechanisms, supported with the CALPHAD simulations and Raman analyses, revealed the formation of non-protective spinel oxides and sublimation of volatile MoO oxides before the stabilization of a protective MO (M = Al,Cr) layer, especially for the AlCoCrFeNiMo alloy.

中文翻译：

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AlxCoCrFeNiMoy 高熵合金的自蔓延高温合成：热化学建模、微观结构评估和高温氧化行为

在本研究中，通过成本高效且节能的热化学建模辅助 (FactSage™) 铝热自蔓延高温合成 (SHS) 方法合成 AlCoCrFeNiMo (0.5 < x < 3, y = 0.5,1) 合金的可行性调查了。此外，还利用真空电弧熔炼机将选定的SHS合金吸铸成棒材形状，并研究了选定合金的显微组织变化和氧化行为。表征结果表明，可以通过热化学建模辅助 SHS 方法成功合成 AlCoCrFeNiMo (0.5 < x < 3, y = 0.5,1) 中间合金，并进行大量成分控制。研究发现 SHS 合金的微观结构由 FCC-A1、BCC（A2、B2）和 σ 相组成，其比例取决于成分。研究发现，增加 Al 含量可将 AlCoCrFeNiMo 系统合金的硬度从 278 HV 提高到 829 HV。另一方面，对于 AlCoCrFeNiMo 体系，最初具有从 Al0.5 到 Al1.0（从 659 HV 到 903 HV）的增加效果，然后随着 Al 的进一步添加，硬度降低到 773 HV 的水平。吸铸合金表现出相当相似的微观结构，具有相似的相成分和硬度值。作为总体趋势，由于冷却速率较高，底漆 B2 相分数增加。氧化研究表明，B2 含量较高（919 HV）的 Al3.0Mo0.5 合金在 800 °C 空气中暴露 100 小时后表现出更好的抗氧化性。假设的缩放机制，在 CALPHAD 模拟和拉曼分析的支持下，揭示了在保护性 MO (M = Al,Cr) 层稳定之前，非保护性尖晶石氧化物的形成和挥发性 MoO 氧化物的升华，特别是对于 AlCoCrFeNiMo 合金。