I would like to know about possible applications of DIC in mechanical testing and the field of materials science, when I search there is the general topics of DIC usages, but I would like to know applications in mechanical testing in material science.
Digital Image Correlation is used a few different ways in mechanical testing. On larger samples, it can be used as a digital extensometer to measure the overall strain in the sample. For ductile samples, it can also show a map of strain fields and how those fields grow fastest around the point of failure. This is especially useful for a heterogeneous sample, e.g. in samples with compositional gradients. The experimental strain fields can be used in combination with finite element modeling to give an idea of the stress state, which often determines failure and can be used to calibrate failure models . Using two simultaneous camera angles can also give you an idea of the 3D strain field of the sample.
The second way DIC is commonly used is to expose grain-scale deformation mechanisms on smaller samples. The surface grain deformation can be mapped using optical microscopy, but this method becomes very powerful when done inside an SEM with nanoparticles providing the speckle pattern . At such scales, the mechanisms of twinning and slip can be directly compared to mesoscale models such as crystal plasticity finite element methods.
 I'd suggest groups like Allison Beese's at Penn State for this; see doi:0.1016/j.actamat.2020.08.066 for macroscopic experiments with computational comparison or arxiv:2001.11611 for the functionally graded materials fabricated by additive manufacturing (no mechanical testing published for these yet -- FGMs still often crack during the build and need refined compositional pathways to avoid this).
 Sam Daly at UC Santa Barbara is well-established in these techniques; see doi:10.1007/s11340-016-0217-3 for the SEM-DIC technique or doi:10.1016/j.ijplas.2020.102917 for a recent comparison with crystal plasticity models.