Écrouissage d’alliages d’aluminium

A study of AlSi5Cu3Mg alloy produced by laser powder bed fusion: porosity assessment, microstructure, mechanical properties

“…15), the dislocations are more diffuse, except at the edges of the silicon polyhedrons where significant concentration is visible. This point also makes it possible to understand that, in our case, the strain hardening rate is lower in the T6 temper than in the as-built temper, but not extremely low as stated in [49]. As a matter of fact, the particular structure of the LPBF-processed alloy in T6 temper shows the presence of silicon polyhedrons with sizes ranging between 0.5 and 4 mm (Fig.…”

“…As a matter of fact, if the yield strength is maximum for a fine dispersion of precipitates being 10 to 50 nm in size equivalent to a T6 temper (Figs. 5c, 12 and 13a), the strain hardening rate (as well as the normalised strain hardening rate) in this temper is rather low [49] (Fig. 13b).…”

“…The maximum strain hardening rate is reached for particle sizes close to the sizes of the dislocation cells, i.e. approximately 1 mm [49]. Thus, the explanation for the higher normalised strain hardening rate in the as-built temper than in the T6 temper lies in the very structure of this temper, that is to say the fine dendrites (Figs.…”

“…These good mechanical properties are the result of a fine and dense precipitation of the u 00 phase, as observed on Figure 5c. As a matter of fact, it is an admitted fact that the yield strength of an alloy stems from the ability of obstacles, such as precipitates, to hinder the motion of moving dislocations [46,49]. The yield strength increases simultaneously with the size of the precipitates, as long as the precipitates are sheared by the dislocations.…”