Enhancement of the strength-ductility synergy of Al-Si-Mg alloys via C-doped TiB₂ particles

We report novel C-doped TiB₂ particles introduced into an Al-Si-Mg alloy. The impact of C-doped TiB₂ particles on the α-Al grain and associated mechanical properties were systematically investigated. These particles were introduced via a master alloy (Al-TBC master alloy, or Al-TBC for short). The results show that the C-doped TiB₂ particles have a dramatical nucleation capability for the α-Al grain, thus eliminating the grain refinement problem of Si “poisoning” in the A357 alloy (one typical category in Al-Si-Mg alloy). As a result, the average grain size of α-Al can be refined to 140 μm from 490 μm by adding 0.5 wt% Al-TBC. The C-doped TiB₂ particles can also enhance the strength-ductility synergy of A357 alloy at room temperature. At 0.5 wt% Al-TBC, the ultimate tensile strength, yield strength, and elongation of T6-treated A357 alloy are 370.1 ± 1.2 MPa, 302.5 ± 7.5 MPa, 12.38 ± 1.2 %, respectively. This work provides a novel prospect for resolving the problem of Si “poisoning” in grain refinement and strength-ductility trade-off in hypoeutectic Al-Si alloys via C-doped TiB₂ particles.