The mechanical properties of Al-Zn-Mg-Cu alloys produced via wire arc additive manufacturing (WAAM) are often weakened by the presence of continuous and coarse precipitated phases, which significantly limits their practical applications. In this study, high-entropy alloy (HEA) particles were incorporated into Al-Zn-Mg-Cu alloy during the WAAM process, which inhibits the continuity of precipitated phase, and the mechanism of microstructure evolution and macroscopic mechanical properties optimization of the components are explored. The results show that HEA particles promote grain refinement, and disrupt the formation of continuous precipitated phase along the grain boundary by generating plenty of fine spot-like precipitated phases, thus inhibiting grain boundary segregation. The spot-like precipitated phases are connected via a slender second-phase-band. The primary precipitates include the metastable , stable , and phases, and the diffusion of solute atoms forms the AlNi and Al(Ni, Cu) phases. The tensile strength increases from 247.4±5.9 MPa to 326.2±19.7 MPa in the horizontal direction and from 273.0±13.7 MPa to 335.4±11.1 MPa in the vertical direction, which correspond to increases of 31.9 % and 22.9 % respectively. The enhancement of mechanical properties is mainly attributed to Hall-Petch, Orowan, load-transfer, solid-solution and dislocation strengthening mechanisms. Only slight variation occurred in the elongation, the increased number of fine spot-like precipitated phases and grain boundaries hinder the crack propagation, while the increased number of pores facilitates the crack propagation, and these effects almost balance each other out in competition. These findings are expected to provide new insights into the microstructure optimization of WAAM components, thereby meeting more practical applications.

中文翻译：

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高熵合金颗粒增强线材增材制造Al-Zn-Mg-Cu合金的显微组织演变及力学性能影响机制

通过电弧增材制造 (WAAM) 生产的 Al-Zn-Mg-Cu 合金的机械性能往往因连续且粗大的析出相的存在而减弱，这极大地限制了其实际应用。本研究在WAAM过程中将高熵合金（HEA）颗粒掺入Al-Zn-Mg-Cu合金中，抑制析出相的连续性，并探讨了组件的微观结构演变和宏观力学性能优化的机制。被探索。结果表明，HEA颗粒促进晶粒细化，通过产生大量细小的点状析出相，破坏沿晶界连续析出相的形成，从而抑制晶界偏析。点状沉淀相通过细长的第二相带连接。初生析出物包括亚稳态相、稳定相和相，溶质原子的扩散形成AlNi和Al(Ni,Cu)相。水平方向抗拉强度从247.4±5.9 MPa增加到326.2±19.7 MPa，垂直方向从273.0±13.7 MPa增加到335.4±11.1 MPa，分别增加了31.9%和22.9%。力学性能的提高主要归因于Hall-Petch、Orowan、载荷传递、固溶和位错强化机制。伸长率仅发生轻微变化，细小点状析出相和晶界数量的增加阻碍了裂纹的扩展，而孔隙数量的增加则有利于裂纹的扩展，这些影响在竞争中几乎相互平衡。这些发现有望为WAAM组件的微观结构优化提供新的见解，从而满足更多的实际应用。