Investigating fracture of nanoscale metal-ceramic multilayers in the transmission electron microscope

In-situ transmission electron microscopy is used to investigate crack propagation parallel.to the interfaces of a Ti/ZrO2 multilayer. The cracks propagate along the middle of the 100 nm thick polycrystalline Ti layers, causing extensive dislocation activity, void coalescence, and crack bridging. The plastic zone size has been determined from the range of dislocation activity and agrees well with estimates of the toughness obtained from the measured crack tip opening displacement. The toughness is much smaller than in bulk Ti, which we attribute to the constraint on dislocation activity and cropping of the plastic zone by the small Ti layer dimensions. (C) 2015 Elsevier Ltd. All rights reserved.