Effects of annealing temperature on the interfacial microstructure and bonding strength of Cu/Al clad sheets produced by twin-roll casting and rolling

• Published in: Journal of materials processing technology 2020-11, Vol.285, p.116804, Article 116804
• Main Authors: Mao, Zhiping, Xie, Jingpei, Wang, Aiqin, Wang, Wenyan, Ma, Douqin, Liu, Pei
• Format: Article
• Language: English
• Subjects: Aluminum; Annealing; Bonding strength; Clad sheet; Cold rolling; Cold treatment; Copper; Crack propagation; Cracks; Fractures; High temperature; Intermetallic compounds; Metallurgy; Microstructure; Peel strength; Rolling; Sheets; Temperature; Thickness; Twin roll casting
• ISSN: 0924-0136; 1873-4774
• DOI: 10.1016/j.jmatprotec.2020.116804

Low-temperature annealing at 250 °C has increased the metallurgical bonding rate of the interface and controlled the intermetallic compound layer thickness, which increased the average peel strength to approximately 39 N/mm. However, high-temperature annealing caused the bonding strength to decrease sharply. [Display omitted] In this paper, Cu/Al clad sheets were prepared by twin-roll casting and multi-pass cold rolling. Annealing treatment was performed at temperatures of 250 °C, 300 °C, 350 °C and 400 °C, separately. The influences of the annealing temperature on the interface layer structure, peel strength and peeled surface microstructure of the clad sheets were studied. The crack propagation behavior in the peeling process of the clad sheets was revealed, and the strengthening mechanism of the interface was explained. The results showed that the Cu/Al interface metallurgical bonding rate increased and the intermetallic compound layer thickness could be controlled within 550 nm after annealing at 250 °C, which encouraged more cracks to propagate along the Al matrix, and the average peel strength could reach approximately 39 N/mm. However, after high-temperature annealing treatment (350 °C and 400 °C), the clad sheet broke completely in the intermetallic compound layer, and a large number of cleavage fractures appeared, which caused the bonding strength to decrease sharply.