Thin-wall Al–Si components reinforced with 2 wt.% FeCoNiCrAl HEA particles were produced by HPDC. The results show that, at a constant intensification pressure of 50 MPa, increasing the casting temperature from 690 to 730°C leads to coarsening of Fe-rich phases and eutectic Si, whereas 710°C provides a balance between melt fluidity and high cooling rate, promoting the cooperative refinement of secondary solidification grains (SSGs) and externally solidified grains (ESGs) and minimising shrinkage sensitivity. HEA particles form flat and dense metallurgical interfaces with the Al–Si matrix, and Mg 2 Si enrichment is observed at the particle surfaces in the last-to-freeze regions. Increasing the intensification pressure from 20 to 80 MPa further refines α-Al grains and Fe-/Si-rich second phases and significantly enhances solidification feeding. An intensification pressure of 80 MPa reduces the total porosity to ∼0.21 %, markedly lowers the shrinkage-pore fraction, and leaves residual defects dominated by fine, blunt gas pores with an average sphericity of ∼0.58. Under identical HPDC conditions, the single-runner gating system produces overall finer grains and a much lower volume fraction of shrinkage cavities than the double-runner system, albeit at the cost of a higher proportion of gas pores, while the double-runner system is dominated by shrinkage defects. Consequently, the H-type system achieves an as-cast, heat-treatment-free strength–ductility combination of YS≈207 MPa, UTS≈398.1 MPa and EL≈8.2 %. The strength is mainly governed by matrix strengthening and the overall porosity level, whereas the elongation is exponentially sensitive to the “effective defect size.”
Zhao et al. (2026) studied this question.