SEM-DIC characterization of the damage mechanism of an AlSi10Fe0.7 casting alloy on the microstructure scale
Year: 2024
Type: article
Abstract: Various brittle phases are present in commercial cast aluminum alloys, which strongly influence their mechanical behavior. Among these, silicon precipitates are nearly omnipresent, as Si is a common alloying element. In secondary alloys, usually Fe-containing phases cannot be avoided, and they tend to degrade the mechanical properties. The interaction between the silicon phase and the failure-critical intermetallic phase in the Al-Si-Fe phase system (β- Al 5 FeSi ) is studied in this paper in high resolution. A model alloy AlSi10Fe0.7 was defined, which is composed of a large grain Al-matrix, Si-precipitates and the plate-like β- Al 5 FeSi phase. The goal of the study was to identify “hot spots” in the microstructure from which cracks may initiate under mechanical loading. The main tool was a deformation analysis via digital image correlation in the SEM (SEM-DIC). This allows the identification and tracking of developing strain localizations at different potential crack initiation sites with a high resolution as well as capturing an overview over the whole specimen. An adapted frame averaging script minimized measurement errors induced by drift. The SEM-DIC results show that the deformation field is governed by the elastic incompatibility of the microstructural constituents. Crack initiation occurs because of the detachment of the Si + β- Al 5 FeSi phase boundary. Cracks then cross the phase boundary and propagate along twin boundaries in the β- Al 5 FeSi phase. Final failure is caused by linking fractured brittle plate-like particles. • A deformation analysis of a secondary AlSi casting alloy was concluded via SEM-DIC. • The interaction between the brittle silicon phase and the β- Al 5 FeSi phase was studied. • Crack initiation occurs because of the detachment of the Si + β- Al 5 FeSi phase boundary. • It is indicated that the fracture of the β-platelet is governed by the crack's propagation between altering twin boundaries.
Source: Materials Characterization
Institution: University of Kassel
Language: English
Subfield: Aerospace Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,470
OpenAlex ID: W4403574488