Effects of (TiB2 + ZrB2) nanoparticles on microstructure and properties of 7055Al matrix composites

摘要

The in situ (TiB2+ZrB2)/7055Al composites were successfully fabricated from the 7055Al-K2TiF6-K2ZrF6-KBF4 system by a direct melt reaction method. Microstructural observations revealed that the nanoparticles were distributed relatively uniformly in the aluminium matrix, and that these nanoparticles exhibit various shapes such as spherical, hexagonal and cubic, with an average size of about 80 nm. Mechanical property testing showed that the strength and Young's modulus of the composites increased significantly in comparison to the 7055 matrix alloy. The maximum ultimate tensile strength was approximately 361 MPa, with a yield strength of 323 MPa and an elongation of 3.6%, which constitute increases of 31.3%, 28.7% and 44% when compared to the 7055Al alloy, respectively. The strengthening mechanisms of the fabricated composites were also discussed.