Microstructure and corrosion resistance of ZL205A alloy through pore architecture optimization under hot isostatic pressing

Abstract This study investigated the effects of prefabricated pore structures combined with hot isostatic pressing (HIP) on the densification and corrosion resistance of ZL205A cast aluminum alloy. Results indicate that a rational pore structure design prior to HIP significantly enhances densification efficiency and improves the service performance of aluminum alloy components. Unlike conventional HIP methods, where interconnected pores hinder complete densification due to internal pressure equilibrium, the introduction of sealed pores enhances the effective pressure differentia, significantly promoting creep-induced pore closure. Comprehensive characterization using SEM (Scanning Electron Microscope), EDS (Energy Dispersive x-ray Spectroscopy), XRD (x-ray Diffraction), nanoindentation, and electrochemical testing confirmed that the proposed strategy leads to grain rearrangement, reduced porosity, and the formation of a denser passivation film, significantly improving mechanical strength and corrosion resistance. Under HIP conditions of 525 °C and 100 MPa, pre-drilled specimens exhibited significant pore closure. Corrosion resistance and mechanical properties were significantly improved compared to undrilled specimens. The research results show that adopting a reasonable pore structure design before hot isostatic pressing can significantly improve both densification efficiency and service performance of aluminum alloy components.