Abstract Micro-mechanical properties such as nanohardness, elastic modulus, fracture toughness, etc. of composite coatings which consist of Al2O3 layer, Al layer and FeAl layer were evaluated by using nanoindentation method. The micrographs of nanoindentation were observed using a scanning electron microscopy (SEM). The effect of pores on Load-displacement response and crack propagation was investigated. The results show that there are some pores at micron scale or sub-micron scale within ceramic coatings. Elastic modulus and hardness of ceramic coating are about 226.4Gpa, 19.6Gpa, respectively. Mechanical properties of ceramic coatings are very discrete when the nanoindentatin depth is set as 250nm. The resistance of crack propagation of Al2O3 layer is large than that of FeAl layer. Radial crack emerges from the corner of residual impression of FeAl layer and propagates along straight line. Radial crack and lateral crack appear at nanoindentation of PEO coating and the cracks’ paths are deflected.
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