Nanoscale deformation and cracking studies of advanced metal evaporated magnetic tapes using atomic force microscopy and digital image correlation techniques

A custom designed microtensile tester was integrated with an atomic force microscopy (AFM) to perform in situ tensile tests on two advanced metal evaporated (ME) magnetic tapes – ME/polyethylene terephthalate (PET) (with PET as a substrate) and ME/polyethylene naphthalate (PEN) (with PEN as a substrate) where the tape surfaces were imaged simultaneously by AFM during tensile loading. The digital image correlation technique was used to process the AFM images and quantitatively measure local, nanoscale deformation for both front coat and back coat of the ME tapes subjected to uniaxial tensile loading. The surface morphology change, strain distribution evolution and crack initiation and propagation during tensile loading are discussed with the structures and mechanical properties of the ME tapes.