Microstructural Evolution of PBF-LB AlSi10Mg under Different Heat Treatment Conditions

Author(s)

Rojas-Arias, N. ; Unti, L. F. K. ; Valim, D. B. ; Gabriel, A. H. G. ; Fonseca, E. B. ; Lopes, E. S. N.

• Document type: Journal article
• Source: MATERIALS RESEARCH-IBERO-AMERICAN JOURNAL OF MATERIALS; v. 28, p. 9-pg., 2025-01-01.

Abstract

Laser-based powder bed fusion (PBF-LB) of AlSi10Mg alloys faces non-equilibrium solidification, resulting in a microstructure of alpha-aluminum phase matrix and an interconnected, fibrous alpha-silicon-rich phase network. The development of heat treatment (HT) routes tailored specifically for PBF-LB parts are essential, as standardized procedures may not yield optimal results. This study investigates the effect of different HTs on the microstructural characteristics and hardness of AlSi10Mg parts. Analyses revealed that the as-built (AB) microstructure exhibited a typical cellular-dendritic solidification structure. The eutectic alpha-Si-rich network partially degenerated after direct aging (DA) and stress relieving (SR), while solution annealing (SA), and solution annealing + aging HT erased the solidification microstructure, producing alpha-Si-rich precipitates dispersed within the alpha-Al matrix. Columnar grains exhibited preferential epitaxial growth along {001} planes in the <001> direction, with no significant changes observed after HTs. The AB sample displayed a hardness of 122 HV, increasing up to 149 HV after DA. Conversely, SR and SA led to a hardness reduction between 61 and 77 HV. While the DA HT maintains the AB microstructural characteristics with a hardness increase, SR and SA HTs modify the solidification microstructure, reducing hardness. (AU)

• FAPESP's process: 18/06045-0 - Advanced manufacturing: exploration of methods for control and validation of powder bed fusion process in additive manufacturing process
• Grantee: Éder Sócrates Najar Lopes
• Support Opportunities: Research Grants - Young Investigators Grants