Aging behavior and mechanical properties of ultra-fine grained Al2024-2TiN composite prepared by spark plasma sintering

Highlights: • The yield strength, tensile strength and elongation of as-aged Al2024-2TiN were 359.1 MPa, 783.2 MPa, and 9.4%, respectively. • The grain size of aged Al2024-2TiN was 452.4 nm, which was significantly smaller than 3.2 μm of Al2024. • TiN nanoparticles promoted the aging kinetics of Al2024-2TiN. • The thermal diffusion activation energies of S′ in Al2024-2TiN and Al2024 were 78.98 kJ/mol and 82.06 kJ/mol, respectively. 2 wt%TiN nanoparticles reinforced ultra-fined grain Al2024 composite (Al2024-2TiN) and ultra-fined grain Al2024 alloy were prepared by high-energy ball milling, spark plasma sintering (SPS), and hot compression deformation. The effect of TiN nanoparticles on aging behavior and mechanical properties of Al2024-2TiN composite was investigated. The results show that, with the introduction of TiN nanoparticles, the tensile strength of as-aged Al2024-2TiN composite increased from 568 MPa of Al2024 alloy to 783 MPa, while the yield strength and elongation decreased from 376.5 MPa and 12.7% to 359.1 MPa and 9.4%, respectively. The average grain size of as-aged Al2024-2TiN composite was 452.4 nm, smaller than 3.2 μm of Al2024 alloy. TiN nanoparticles reduced the dissolution of the second phases during solution treatment, and decreased the number of age precipitating phases which resulted in the yield strength of Al2024-2TiN composite being lower than that of Al2024 alloy. Nevertheless, TiN nanoparticles promoted the aging kinetics of Al2024-2TiN composite. The peak aging time of 6 h for Al2024-2TiN composite was 2 h earlier than that of Al2024 alloy. The thermal diffusion activation energies of phase S′ precipitated in Al2024-2TiN composite and Al2024 alloy were 78.98 kJ/mol and 82.06 kJ/mol, respectively. Phase S′ precipitation in Al2024-TiN composite became easier.