Sodium borosilicate (SBN) glasses concern an important research topic, as the three components (SiO₂, Na₂O, and B₂O₃) are the principal oxides of many industrial glasses. Within in the ternary SBN oxide glass system, there is a region where amorphous phase separation (APS) is a dominant feature. Moreover, APS has industrial relevance for crush resistant glasses, porous glasses and glass ceramics. Theory, simulations, and experiments clearly reveal two-phases. Additionally, it is hypothesized that three-phase exists for certain chemical compositions. APS inside the glasses induces complex heterogeneous structures at the nano-scale, which alter the glasses' physical and mechanical/fracture properties. However, the connection between the structure of APS glasses and their properties remains poorly understood, especially the stress corrosion cracking (SCC) behavior. Hence, in my PhD, I aim at studying the effects of APS structure on SBN glass SCC behavior. My research focuses on SBN glasses with compositions falling within the hypothesized three-phase APS zone. Annealing pristine (as-fabricated) glasses induces APS. Various techniques were used to capture the evolution of the short- and medium-range order of the glass structure with APS. For example, Atomic Force Microscopy (AFM) images evidence spinodal decomposition in the structure, and its growth with annealing temperature and duration. The evolution of phase size is found to be proportional to the cubic root of annealing time for the fix annealing temperature. Additionally, NMR and Raman spectra help in understanding the short-range structure of the APS glasses. An increase in the fraction of BO₃-ring structural units was observed, confirming the formation of boron-rich phases. The SCC behavior in APS glasses was characterized via an in-house experimental setup designed during my thesis. This experimental setup permits me to capture the propagation of the crack front in a well-controlled environment (T=19±1 ℃ and RH=40.0±0.5 %). From images captured, the crack front velocity as a function of the stress intensity factor can be rendered. These results show the inherent meso-scale structure (~APS size) plays on the environmental limit along with Region I SCC parameters. Interestingly, small size APS makes the glasses more susceptible to SCC. However, larger APS structures tends to re-enhance the SCC resistance, and in some instances, the APS glass outperforms their pristine counterparts. After SCC experiments, AFM imaging provides high-resolution topographical images of the fracture surfaces. Post-mortem analysis reveal that the roughness increases with the phase sizes. Additionally, the fracture surfaces of all the samples were found to fit the structure function models. These are the first results proving the reliability of structure function models with experimental fracture surfaces.