HI Tanwir, it can be generally understood from the microstructure. I am attaching here one image where you can see like stretch marks which generally occur in ductile regions, where more brittle type failure can be understood by looking at the interface. Hopefully, the image can help. Also, if you have any SEM images, you can share so that researchers can comment on.

As Soud Choudhury suggested.... easiest way to see the fracture surface in Scanning Electron Microscopy (SEM). Broadly speaking, ductile fracture appears as dimples and brittle fracture appears as rock candy morphology. Please note, usual optical microscope will not help much due to their low depth of focus... however, one can see the suitability to use powerful stereo microscope for preliminary surface examination. Brittle fracture would appear shinier than the dull ductile fracture... just preliminary examination.

Fracture surface in Scanning Electron Microscopy (SEM). The ductile fracture appears as dimples and brittle fracture appears as rock candy morphology as shown by (SEM), after the fracture materials are different shapes as cup and cone.