Investigation of the Thermomechanical Properties and Fracture Behaviour of Magnesia-Based Materials by Using a Refined Digital Image Correlation Method
Fracture behaviour of magnesia-based model materials was investigated by coupling a refined Digital Image Correlation method (2P-DIC) with theWedge Splitting Test (WST). Despite the rather similar elastic and dilatometric properties of spinel and hercynite single constituents, peculiar microcracking patterns were observed, especially in magnesia-hercynite. Extensive diffusion between magnesia and hercynite during sintering led to the formation of spinel solid solutions around hercynite aggregates. These solid solutions contributed to create numerous fine microcracks confined within the diffusion zone. Initially present within the microstructure, microcrack networks promote an increase of specific fracture energy during WST experiments. Strain fields measured by 2P-DIC revealed extensive crack branching for magnesia-hercynite materials. The 2P-DIC and WST measurements showed that microcrack networks promoted the development of the FPZ, which in turn induced higher fracture energies.