In the present investigation, the AlFe alloy system is developed by using the solid-state friction stir alloying (FSA) technique. The objective is realized by using multiple passes (1–4) of FSA with 100% overlap at constant process parameters. The TEM analysis confirms the interfacial reaction between the Al and Fe particles leading to the formation of nano-sized hard and brittle Al₁₃Fe₄ intermetallic (IMC) phase. The SEM, EDS, and XRD analysis also indicates the existence of a very small amount of Al₅Fe₂ IMC layer at the AlFe interface. The microstructural analysis from EBSD confirms that the grain size is reduced from ~27 μm in the base material to ~2 μm in the 4 pass FSAed AlFe alloy through dynamic recrystallization mechanism. The microhardness in the SZ is increased by ~14% in the 4 pass FSAed AlFe alloy as compared to that with 1 pass. The increased hardness of AlFe alloys as compared to the 4 passes processed Al alloy (without Fe) suggest that the AlFe alloys system presented here can be an alternative solution for underwater friction stir welding (UFSW) to compensate for the stir zone softening occurred by the high heat input process parameters or precipitate dissolution in the heat treatable Al alloys. The ultimate tensile strength and percentage elongation are increased by ~30% and ~48% in the 4 pass FSAed AlFe alloy as compared to the alloy fabricated at 1 pass, respectively. The increased strength and hardness of the 4 passes FSAed alloy is attributed to the increased reaction rate between Al and Fe particles owing to the higher heat input which results in the precipitation of a more number of Al₁₃Fe₄ IMC phases during 4 passes. Also, the uniform dispersion of nano-sized IMC phases in 4 passes FSAed alloy as compared to the alloy fabricated with 1 pass, contribute significantly to the dislocation blockade and dispersion strengthening mechanism. The shreds of evidence provided in the present investigation suggest that the precipitation hardening is the dominant strengthening mechanism in the AlFe alloy system as compared to the Hall-petch strengthening mechanism.

在目前的研究中，铝铁合金系统是通过使用固态搅拌摩擦合金化 (FSA) 技术开发的。该目标是通过在恒定工艺参数下使用具有 100% 重叠的 FSA 多次通过 (1-4) 来实现的。TEM 分析证实了 Al 和 Fe 颗粒之间的界面反应导致纳米尺寸的硬而脆的 Al ₁₃ Fe ₄金属间化合物 (IMC) 相的形成。SEM、EDS 和XRD 分析还表明在Al Fe 界面存在非常少量的Al ₅ Fe ₂ IMC 层。EBSD 的微观结构分析证实，晶粒尺寸从基材中的 ~27 μm 减小到 4 道 FSAed Al 中的 ~2 μmFe合金通过动态再结晶机制。与 1 道次相比，4 道次 FSAed Al Fe 合金的 SZ 显微硬度增加了约 14% 。与 4 道次加工的铝合金（不含 Fe）相比，Al Fe 合金的硬度增加表明，此处介绍的 Al Fe 合金系统可以作为水下搅拌摩擦焊 (UFSW) 的替代解决方案，以补偿发生的搅拌区软化由于高热输入工艺参数或可热处理铝合金中的沉淀溶解。在 4 道 FSAed Al 中，极限抗拉强度和伸长率分别增加了 ~30% 和 ~48%Fe 合金分别与通过 1 道次制造的合金进行比较。4 道次 FSAed 合金的强度和硬度增加归因于 Al 和 Fe 颗粒之间的反应速率增加，这是由于更高的热输入导致在 4 道次期间析出更多数量的 Al ₁₃ Fe ₄ IMC 相。此外，与 1 道次制造的合金相比，4 道次 FSAed 合金中纳米尺寸 IMC 相的均匀分散，显着有助于位错阻断和分散强化机制。本研究提供的证据表明，与霍尔-佩奇强化机制相比，沉淀硬化是 Al Fe 合金体系中的主要强化机制。