Mechanical spectroscopy study of as-cast and additive manufactured AlSi10Mg.

The AlSi10Mg alloy produced by casting (AC) and additive manufacturing (AM) technology of laser powder bed fusion (L -PBF) has been investigated through mechanical spectroscopy (MS). In addition to the grain boundary peak P GB the Q −1 curves of both materials exhibit two other relaxation peaks, P1 (H = 0.8 ± 0.05 eV; τ 0 = 10−11±1 s) and P2 (H = 1.0 ± 0.05 eV; τ 0 = 10−13±1 s), depending on the interaction of dislocations with solute elements (Si and Mg). Relaxation strengths of P1, P2 and P GB of AM alloy are greater than those of the AC one owing to the finer structure of Al cells and the higher amount of Si and Mg in supersaturated solid solution induced by the rapid solidification typical of the L -PBF process. After successive MS test runs relaxation strengths of P1 and P2 peaks in both the examined materials decrease due to the precipitation of Si atoms and dislocation density recovery. Such decrease is more pronounced in AM alloy where change of cell shape and increase of cell size is observed. Dynamic modulus of AM alloy exhibits an anomalous trend in the first test run that is no more present in successive runs. The irreversible process giving rise to such anomalous behavior is the closure of pores of nanometric size. • AlSi10Mg produced by casting (AC) and additive manufacturing (AM) has been investigated through mechanical spectroscopy (MS). • Q-1 curves of both materials exhibit the grain boundary peak P GB and two other relaxation peaks (P1 and P2). • The MS results have been correlated to microstructural information from light microscopy, XRD, TEM and SEM. • The P1 and P2 peaks depend on the interaction of dislocations with solute elements (Si and Mg). • Dynamic modulus of AM alloy exhibits an anomalous trend in the first test run that is no more present in successive runs. [ABSTRACT FROM AUTHOR]