Investigating the mechanical behavior and microstructure of basalt fibers-aluminum composite fabricated by thixomixing method

Fabricating Metal matrix composites (MMCs) reinforced by fibers is one of the biggest issues in the engineering in various industries, due to having production limitations. In this research has been tried to fabricate aluminum matrix composites reinforced by fibers through thixomixing as novel method in semi-solid state and by helping shear force. For doing this, the basalt fibers (with the volume fraction of 2, 4, and 6) were dispersed into the molten A356 aluminum and by creating the shear mixing in the range of semi-solid temperature of aluminum, the composites were fabricated. For investigating the mechanical behavior of fabricated composites, the Brinell hardness and shear punch tests were used. Also, microstructural investigations and elemental analysis by scanning electron microscope were performed. The obtained results showed that by increasing the fibers content, the hardness and shear strength were simultaneously improved, which resulted to improve the ultimate strength of composite. The shear strength from 119.1 MPa (for without fibers sample) to 132.3 MPa (in reinforced composite by 6 vol.% basalt fibers) was increased. Also, the hardness test results showed an increase in Brinell hardness from 62.3 to 70.8 Hb in the sample with 6 vol.% of basalt fibers. The ultimate tensile strength in this sample also showed the 10.9% improvement. Microstructural investigations depicted that the formation of intermetallic compounds at the interface caused to improve the mechanical properties.