• The CRE Al-Ti-V-B master alloy achieves a 89.62% reduction in grain size of A356 alloy, from coarse dendrites to 151.8 μm, significantly enhancing mechanical properties.
• Optimal refinement parameters are 0.3wt.% master alloy addition and 20 min holding time, yielding tensile strength of 196.11 MPa and elongation of 5.75% in as-cast state.
• After T6 heat treatment, the refined alloy exhibits tensile strength of 290.1 MPa and elongation of 3.09%, demonstrating improved ductility and strength.
• The refined grains promote crack path deflection and localized plastic deformation, reducing brittle fracture tendency and enhancing energy dissipation.