Microstructure, Texture and Mechanical Properties of Al-SiC Composite with Bimodal Structure Fabricated by Multi-Layer Accumulative Roll Bonding

Abstract

A multi-layer accumulative roll bonding (MARB) process was applied to fabricate Al-1 vol% SiC composite (M3) with bimodal structure consisting of 1.07 μm ultrafine grain layers and 0.48 μm finer grain layers. The differences in microstructure, texture and mechanical properties of the M3 samples were systematically compared with conventional MARB-processed Al (M1) and bimodal Al (M2) samples. Optical microscopy (OM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) analysis were used to characterize the microstructure evolution of the composites, while the mechanical properties were analyzed by tensile and microhardness tests. As revealed by EBSD results after three cycles, the M3 samples had a bimodal grain structure of 0.48 and 1.07 μm. The texture components of the M3 samples were Brass {011} <211>, S {123} <634>, Cube {001} <100> and Copper {112} <111>. According to SEM observation, ductile fracture of M3 was characterized by acicular dimple and circular micropores. Bimodal Al-SiC composites with high strength (225 MPa) and elongation (13%) were finally synthesized after three cycles. Compared with M1 sheets, the strength and elongation of the M3 sheets increased by 23.2% and 7.4%, respectively, indicating that the M3 samples achieved a synergistic improvement in strength and plasticity.