Microstructure and Mechanical Properties of Layered Al/MgLiZnY/Al Composite Sheets Processed by Accumulative Roll Bonding (ARB)

Layered composite sheets consisting of Mg-8Li-6Zn-1.2Y (in wt.%, designated as LZW861) alloy and commercially pure Al (AA1060) were fabricated via accumulative roll bonding (ARB), and their microstructure and mechanical properties were systematically investigated in this work. The results revealed that with increasing ARB passes, the number of heterogeneous interfaces within the sheets significantly increased, and the constituent phases, including α-Mg, β-Li, and the quasicrystalline I-phase, were markedly elongated along the rolling direction. Moreover, deformation twins formed within the β-Li phase, leading to a pronounced fibrous microstructure, and the thickness of the interfacial diffusion layer, primarily composed of intermetallic compounds (IMCs) Mg 17 Al 12 and Al 3 Mg 2 , progressively increased. Both the hardness and strength of the layered composite sheets exhibited continuous enhancement with increasing ARB passes. Specifically, the nanohardness at the interface after 2 ARB passes reached a high value of 2.4 GPa, while the ultimate tensile strength achieved 260 MPa, with an elongation-to-failure still exceeding 20%. Fracture mechanism analysis indicated a mixed fracture mode: for the as-bonded sample (ARB 0), fracture originated from microcracks associated with the I-phase; for the ARB-processed samples (ARB 1 and ARB 2), cracks preferentially nucleated at the heterogeneous interfaces due to the applied tensile stress exceeding the bonding strength of the interfacial IMCs.