Fracture mechanism of an Al/AlN/CrAlN gradient coating on nitrogen implanted magnesium alloy

The fracture behavior of an Al/AlN/CrAlN gradient coating on nitrogen implanted magnesium alloy was investigated using in-situ compression in a transmission electron microscopy (TEM) and finite element analysis. Results showed that the ductile Al layer was subjected to the highest interfacial stress due to the significant difference between the mechanical properties of Al and AlN. The high interfacial stress induced severe plastic deformation that led to fracture failure in the Al layer near the Al/AlN interface. The experimental results provide clue for the structural design of gradient coatings.