PSI - Issue 7

A. Brueckner-Foit et al. / Procedia Structural Integrity 7 (2017) 36–43 A. Brückner-Foit/ Structural Integrity Procedia 00 (2017) 000–000

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a) b) Fig. 7 Agglomeration of ß-Al 5 FeSi inclusions forming clusters with cavities in which pores are retained: a) 0.6% Fe content; b) 2.3% Fe content. The size of these particles increase exponentially with the Fe content (see Fig. 8a), leading to a dramatic decrease of the mechanical properties. Nevertheless, a significant increase of the mechanical properties can be observed after heat-treatment as a result of the fragmentation and dissolution of these particles (see Fig. 8b and 8c). This phenomenon can also be noted in the SEM observations of the fracture surfaces from the specimens with high Fe content before and after heat treatment. Fig. 9a shows the cleavage fracture of massive brittle ß-Al 5 FeSi plates in the non-heat-treated specimen with 1.85% Fe content, whereas a more ductile fracture with a significant reduction of the fraction of Fe rich inclusions can be observed on Fig 9b.

a) c) Fig. 8 Influence of the Fe content before (blue) and after (orange) heat treatment on: a) max. Feret size of the Fe rich inclusions; b) ultimate strength (MPa); c) elongation at break (%). b)

a) b) Fig. 9 Fracture surfaces of the tensile specimens with 1.85% Fe content before (right) and after (left) heat treat.