A novel strategy of powder assembly & alloying was used to achieve trimodal grain structure in carbon nanotubes (CNTs) reinforced aluminum matrix composites. The soft pure Al and hard 2024Al powders were firstly ball milled with CNTs for CNT/Al and CNT/2024Al flakes with different thicknesses, then were assembled with coarse-grained pure Al powders. Under the confinement of CNTs, these three building blocks evolved into ultrafine grains (UFG) smaller than 500 nm, fine grains (FG) between 500 nm and 2 μm and coarse grains (CG) about 9.8 μm, respectively, while the Al–Cu–Mg matrix achieved by the diffusion of Cu and Mg powders and elemental alloying with Al. Such a UFG-FG-CG trimodal grain structure contributed to superior strength-ductility synergy, as the 1.5 wt% CNT/Al–Cu–Mg composites exhibited tensile strength of 723 ± 6 MPa and elongation of 6.7 ± 0.6%. Therefore, powder assembly & alloying was proved an effective way to design and fabricate heterogeneous structured metal matrix nanocomposites.

一种新的粉末组装和合金化策略用于在碳纳米管 (CNT) 增强的铝基复合材料中实现三峰晶粒结构。软质纯铝和硬质 2024Al 粉末首先与 CNTs 球磨成不同厚度的 CNT/Al 和 CNT/2024Al 薄片，然后与粗粒纯铝粉末组装。在碳纳米管的限制下，这三种结构单元分别演化为小于 500 nm 的超细晶粒 (UFG)、500 nm 和 2 μm 之间的细晶粒 (FG) 和约 9.8 μm 的粗晶粒 (CG)，而 Al-Cu – 通过 Cu 和 Mg 粉末的扩散以及与 Al 元素合金化获得的 Mg 基体。这种 UFG-FG-CG 三峰晶粒结构有助于优异的强度-延展性协同作用，如 1. 5 wt% CNT/Al-Cu-Mg 复合材料的拉伸强度为 723 ± 6 MPa，伸长率为 6.7 ± 0.6%。因此，粉末组装和合金化被证明是设计和制造异质结构金属基纳米复合材料的有效方法。