Enhancing strength-ductility synergy and mechanisms of Al-based composites by size-tunable in-situ TiB2 particles with specific spatial distribution
Composites Part B: Engineering
School of Engineering
This work was supported by National Natural Science Foundation of China (No. 51771081 and No. 51971101), the ‘thirteenth five-year plan’ Science & Technology Research Foundation of Education Bureau of Jilin Province, China (Grant No. JJKH20200971KJ), the Science and Technology Development Program of Jilin Province, China (20190302004GX), the Postdoctoral Science Foundation of China (No. 2020M670849), and the Graduate Innovation Fund of Jilin University (No. 101832020CX139).
The increase in strength usually accompanies by the sacrifice of ductility in the composites. This work proposed a strategy of design and synthesis of in-situ TiB2 particles to effectively tailor the microstructures and to enhance the mechanical performance of Al–Si-based composites. The tuning mechanisms for size and morphology of TiB2 particles were investigated by combustion synthesis in the Al–Ti–B reaction system. The nano/submicron-sized TiB2 particles with desirable morphology were then specially selected to construct high-performance Al–Si-based composites. Thanks to the strong interface bonding with a low crystallographic mismatch, TiB2 particles significantly refined the primary α-Al dendrites, eutectic Si and θ’ precipitates in the composites, which were 79.2%, 51.9% and 37.6% respectively smaller than those of the matrix. Numerical modeling results suggested that submicron-sized TiB2 particles were more likely to be engulfed or serve as heterogeneous sites while nano-sized TiB2 particles would be repulsed to the solid/liquid interface to physically restrict the growth of α-Al dendrites. The strength-ductility trade-off dilemma was broken therefore superior mechanical properties were obtained in the composites. This work provides a novel perspective for manipulating Al–Si-based alloys in terms of avoiding poisoning and achieving microstructural refinement and outstanding strength-ductility synergy.