The role of Si-rich network and its evolution mechanism in SLM AlSi10Mg under rate-temperature coupled loading

Selective laser melted (SLM) AlSi10Mg alloy exhibits a Si-rich network that contributes to its high strength, but the role of the network in its mechanical response remains unclear. Here, the influences of directionality, strain rate, and temperature on the mechanical properties and microstructural evolution of SLM AlSi10Mg alloy were evaluated over a wide range of strain rates and temperatures (10 -4 -4030 s -1 and 213-473 K). The alloy shows transverse isotropy, with higher strength along the build direction. Both yield and flow stresses increase remarkably with the increasing strain rate, whereas increasing temperature reduces them, particularly under quasi-static loading. The Si-rich network acts as an effective barrier to dislocation motion, promoting dislocation multiplication and substructure refinement at high strain rate, thereby contributing to strain-rate strengthening. In contrast, low temperatures suppress dislocation recovery and favor dislocation storage, while elevated temperatures are associated with reduced local lattice curvature and weakened dislocation storage capability, thereby weakening the strain rate strengthening effect. These findings clarify the relationship between macroscopic behavior and microstructural evolution of SLM AlSi10Mg alloy, and provide guidance for designing components subjected to complex loading.