Raman spectroscopy was used to investigate the structure of ion-irradiated α-SiC single crystals at room temperature and 400 °C. Irradiations induce a decrease of the Raman line intensities related to crystalline SiC, the appearance of several new Si–C vibration bands attributed to the breakdown of the Raman selection rules, and the formation of homonuclear bonds Si–Si and C–C within the SiC network. For low doses, the overall sp3 bond structure and the chemical order may be almost completely conserved. By contrast, the amorphous state shows a strong randomization of the Si–Si, Si–C and C–C bonds. The relative Raman intensity decreases exponentially versus increasing dose due to the absorption of the irradiated layer. The total disorder follows a sigmoidal curve, which is well fitted by the direct impact/defect stimulated model. The chemical disorder expressed as the ratio of C–C bonds to Si–C bonds increases exponentially versus the dose. A clear correlation is established between the total disorder and the chemical disorder. The increase of temperature allows the stabilization of a disordered/distorted state and a limitation of damage accumulation owing to the enhancement of the dynamic annealing.

We report that 316L austenitic stainless steel fabricated by direct laser deposition (DLD), an additive manufacturing (AM) process, have a higher yield strength than that of conventional 316L while keeping high ductility. More interestingly, no clear anisotropy in tensile properties was observed between the building and the scanning direction of the 3D printed steel. Metallographic examination of the as-built parts shows a heterogeneous solidification cellular microstructure. Transmission electron microscopy observations coupled with Energy Dispersive X-ray Spectrometry (EDS) reveal the presence of chemical micro-segregation correlated with high dislocation density at cell boundaries as well as the in-situ formation of well-dispersed oxides and transition-metal-rich precipitates. The hierarchical heterogeneous microstructure in the AM parts induces excellent strength of the 316L stainless steel while the low staking fault energy of the as-built 316L promotes the occurrence of abundant deformation twinning, in the origin of the high ductility of the AM steel. Without additional post-process treatments, the AM 316L proves that it can be used as a structural material or component for repair in mechanical construction.