Synergistic Effect of Cr and Ce on Microstructural Development and Strengthening Processes in Al‐3Ti‐1B Refined A356 Alloy

A novel Al‐Ti‐B‐Cr‐Ce master alloy refiner with anti‐Si‐poisoning and fading effect was developed through co‐doping with chromium (Cr) and cerium (Ce). Al ₂₀ Ti ₂ Ce phase in Al‐3Ti‐1B‐0.5Cr‐0.8Ce intermediate alloys can significantly refine the dendrite arms of α ‐Al. The rare earth phase serves as an effective protective shell, which not only inhibits the aggregation and growth of the Al ₃ Ti phase but also reduces the surface energy and agglomeration tendency of the TiB ₂ phase. A small amount of chromium can form CrB ₂ with B and also form the Al ₁₃ Cr ₄ Si ₄ phase, enhancing the anti‐poisoning effect during the refinement process and having a significant refining effect on the Si phase. The incorporation of an Al‐3Ti‐1B‐0.5Cr‐0.8Ce master alloy into A356 aluminum alloy yields significant grain refinement. Notably, the refined grain size can be sustained below 150 µm even after 120 min of holding. Furthermore, the refined alloy exhibits enhanced mechanical properties, tensile strength augmented by 28.7% to 215 MPa, yield strength elevated by 37.0% to 185 MPa, and elongation at break enhanced by 19.1% to 9.82%.