Microstructures and Hardness Prediction of an Ultrafine-Grained Al-2024 Alloy

• Main Authors: Ying Chen, Yuanchen Tang, Houan Zhang, Nan Hu, Nong Gao, Marco J. Starink
• Format: Article
• Language: English
• Published: MDPI AG 2019-11-01
• Series: Metals
• Subjects: high-pressure torsion; al-cu-mg alloy; solute segregation
• Online Access: https://www.mdpi.com/2075-4701/9/11/1182

<b> </b>High-pressure torsion (HPT) is a high efficiency processing method for fabricating bulk ultrafine-grained metallic materials. This work investigates microstructures and evaluates the corresponding strengthening components in the center of HPT disks, where effective shear strains are very low. An Al-4.63Cu-1.51Mg (wt. %) alloy was processed by HPT for 5 rotations. Non-equilibrium grain and sub-grain boundaries were observed using scanning transmission electron microscopy in the center area of HPT disks. Solute co-cluster segregation at grain boundaries was found by energy dispersive spectrometry. Quantitative analysis of X-ray diffraction patterns showed that the average microstrain, crystalline size, and dislocation density were (1.32 &#177; 0.07) &#215; 10^&#8722;3, 61.9 &#177; 1.4 nm, and (2.58 &#177; 0.07) &#215; 10¹⁴ m^&#8722;2, respectively. The ultra-high average hardness increment was predicted on multiple mechanisms due to ultra-high dislocation densities, grain refinement, and co-cluster&#8722;defect complexes.