Aluminum Foam Sandwich: Pore Evolution Mechanism Investigation and Engineering Preparing Optimization

This paper employs an innovative investigation approach to study pore evolution in Al-Si-Mg-Cu alloy within aluminum foam sandwiches (AFS) by integrating data from heating-expansion ratio curves, in situ observation of synchronous radiation, and microscopic analysis of the matrix's microstructure at different stages. Additionally, the cavity design and plate type control for large-scale AFS production are explored. Findings categorize the precursor heating into three stages: rapid heating, solid-liquid transition, and stable foaming. During solid-liquid transition, the expansion rate experiences a sudden drop, associated with pore nucleation and edge cracking of precursors. Pores nucleate as elongated crack-like structures along the rolling direction, guided by the Mg-enriched regions. In stable foaming, these pores evolve, become spherical, and the matrix rapidly expands. Using square tubes for sealing on the preform cavity sides creates a dense edge zone during rolling, halting crack propagation into the powder core. Adopting edge sealing during foaming mitigates boundary effects, thereby improving AFS panel flatness.