The addition of Mn in Al–Fe alloys stabilizes the AlFe metastable phase (orthorhombic structure, 28) owing to the partial occupation of Fe sublattice sites by Mn atoms (formation of Al(Fe, Mn) phase), thereby achieving superior high-temperature strength of Al–Fe–Mn ternary alloys that are manufactured via laser powder bed fusion (L-PBF) process. This study aimed to fundamentally understand the thermal stability of the refined Al(Fe, Mn) phase formed in the L-PBF fabricated Al–2.5%Fe–2%Mn alloy in terms of a thermodynamic approach and the kinetics of morphological changes in the Al(Fe, Mn) phase at elevated temperatures ranging from 200 to 500 ℃. The L-PBF processed samples showed a high hardness of approximately 125 HV due to the formation of numerous dispersoids of the Al(Fe, Mn) phase with sizes of several tens of nanometers in the α-Al matrix containing concentrated solute elements of Fe and Mn. The hardness and microstructure were almost unchanged even after exposure to a high temperature of 200 ℃ for an extended period of 1000 h. Upon exposure to 300 ℃, nucleation and growth of the Al(Fe, Mn) phase occurred locally, particularly at grain boundaries in the α-Al matrix. Such a local growth contributed to a reduction in hardness upon thermal exposure. Simultaneously, numerous nanoscale precipitates were formed in the α-Al matrix, resulting in a suppressed reduction in hardness. Contrary to the result of the thermodynamic calculations, the θ-AlFe phase was scarcely found even after long-term exposure to 500 ℃. The θ-phase formation was accompanied by the dissolution of the refined AlFe metastable phase for strengthening, which significantly reduced the hardness during thermal exposure. The suppressed θ-phase formation could be associated with the thermodynamically stable Al(Fe, Mn) phase developed during the L-PBF process, which predominantly contributed to the high microstructural stability of the L-PBF fabricated Al–Fe–Mn alloy at elevated temperatures.

中文翻译：

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激光粉末床熔合细化Al6(Fe,Mn)相的热稳定性

在 Al-Fe 合金中添加 Mn，由于 Mn 原子部分占据 Fe 亚晶格位置（形成 Al(Fe, Mn) 相），从而稳定了 AlFe 亚稳相（正交结构，28），从而实现了优异的高温性能。通过激光粉末床熔合 (L-PBF) 工艺制造的 Al-Fe-Mn 三元合金的强度。本研究旨在从热力学方法和形态变化动力学方面从根本上了解 L-PBF 制造的 Al-2.5%Fe-2%Mn 合金中形成的细化 Al(Fe, Mn) 相的热稳定性。在 200 至 500 ℃ 的高温下形成 Al(Fe, Mn) 相。 L-PBF处理后的样品表现出约125 HV的高硬度，这是由于在含有浓缩的Fe和Mn溶质元素的α-Al基体中形成了许多尺寸为数十纳米的Al(Fe, Mn)相弥散体。锰。即使在200℃高温下长时间暴露1000小时，硬度和显微组织也几乎没有变化。当暴露于 300 ℃ 时，Al(Fe, Mn) 相局部发生形核和生长，特别是在 α-Al 基体的晶界处。这种局部生长导致热暴露时硬度的降低。同时，α-Al基体中形成大量纳米级析出物，从而抑制了硬度的降低。与热力学计算的结果相反，即使长期暴露在500℃下也几乎没有发现θ-AlFe相。 θ相的形成伴随着细化AlFe亚稳相的溶解以进行强化，从而显着降低了热暴露期间的硬度。抑制的θ相形成可能与L-PBF过程中形成的热力学稳定的Al(Fe, Mn)相有关，这主要有助于L-PBF制造的Al-Fe-Mn合金在高温下具有高微观结构稳定性。温度。