Enhancing strength-ductility synergy in nano-sized TiB2/Al composite via rapid solidification and thermo-mechanical processing

The Al-Cu-Mn (AA2219) composite reinforced by 5 wt% nano-sized TiB₂ particles were fabricated by hot isostatic pressing (HIP) combined with thermal-mechanical processing to achieve a superior strength-ductility combination. Coupling the comprehensive characterizations and microstructure-based analysis, the strength-ductility mechanisms were deeply understood. Results reveal that the uniform dispersed nano-sized TiB₂ particles under the current preparation process helps to improve the mechanical properties of the composite. The introduction of pre-stretch before artificial aging produced a fine θ' and S precipitates. By combining high-resolution TEM and crystal structure analysis, Al(Cu) and S phase at TiB₂/Al interface were identified, and their mismatch (δ) with Al were 3.8 % and 4.8 %, respectively. Mechanisms related to pre-stretch effects on the formation of dislocation, θ' and S precipitates and corresponding structures are discussed, as well as the implications of TiB₂/Al interface characteristics on strength and ductility.