The aim of this study was to identify deformation behavior and strengthening mechanisms of a carbon nanotube (CNT)-reinforced bimodal-grained Al–Cu–Mg nanocomposite and its base alloy fabricated by two-step ball milling, powder metallurgy and extrusion. A superior strength-ductility synergy stemming from the concurrent presence of ultrafine grains (UFGs) and coarse grains (CGs) was achieved. Singly-dispersed CNTs in UFGs and sound CNT/Al interfacial bond contributed to a significant improvement in the strength of the nanocomposite. The predominant strengthening mechanism in the CNT-reinforced nanocomposite was identified to be Orowan looping due to severe shearing of CNTs into nano-sized fragments during ball milling, along with load-transfer and thermal mismatch-induced dislocation strengthening mechanisms. The predicted yield strength of the nanocomposite was in agreement with the experimental value obtained. The findings in this study help pave the way for developing high-performance lightweight materials with a superior strength-ductility synergy via incorporating CNTs with novel bimodal grain structures.

这项研究的目的是确定通过两步球磨，粉末冶金和挤压制备的碳纳米管（CNT）增强的双峰晶粒Al–Cu–Mg纳米复合材料及其基础合金的变形行为和强化机理。由于同时存在超细晶粒（UFG）和粗晶粒（CG）而获得了卓越的强度-延性协同作用。UFG中单分散的CNT和良好的CNT / Al界面键有助于纳米复合材料的强度显着提高。碳纳米管增强的纳米复合材料中最主要的增强机制被确定为Orowan环，这是由于球磨过程中碳纳米管严重剪切成纳米大小的碎片，以及负载转移和热失配引起的位错增强机制。纳米复合材料的预测屈服强度与获得的实验值一致。这项研究中的发现有助于通过结合具有新型双峰晶粒结构的CNT来开发具有卓越的强度-延展性协同作用的高性能轻质材料。