Fracture and debonding behavior of coated brittle alumina layer on ductile aluminum substrate wire

Abstract

The fracture and debonding behavior of the Al2O3 layer coated on a ductile aluminum substrate wire was studied experimentally and analytically. When tensile strain was applied, the brittle Al2O3 coating layer showed multiple cracking perpendicular to the tensile axis. After the multiple cracking, compressive fracture of the Al2O3 layer arose in the circumferential direction when the layer was thinner than around 30 μm, while interfacial debonding between the Al2O3 layer and aluminum substrate arose when it was thicker. Such a difference in behavior between thin and thick layers could be accounted for by the difference in the layer thickness-dependence of the tensile radial stress at the interface and the compressive hoop stress of the Al2O3 layer calculated by the finite element method; the former stress increases while the latter one decreases with increasing layer thickness.