Control of fatigue failure mechanisms in multilayer coatings by varying the architectural parameters of an intermetallic interlayer

A multilayer overlay coating system containing an intermediate intermetallic layer is an architecture expected to show good fatigue resistance. Experimental characterization and modeling simulations were carried out to classify the different crack initiation mechanisms occurring during fatigue of th...

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Bibliographic Details
Published in:Fatigue & fracture of engineering materials & structures 2022-04, Vol.45 (4), p.1035-1051
Main Authors: Lu, Songsong, Cook, Richard, Zhang, Yi, Reed, Philippa
Format: Article
Language:English
Subjects:
characterization
Coatings
Crack initiation
Design optimization
Failure mechanisms
Fatigue cracks
Fatigue failure
fatigue failure mechanism
Fatigue strength
finite element analysis
Fracture mechanics
Interfacial strength
Interlayers
multilayer coatings
Multilayers
Protective coatings
Surface cracks
Thickness
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Summary:A multilayer overlay coating system containing an intermediate intermetallic layer is an architecture expected to show good fatigue resistance. Experimental characterization and modeling simulations were carried out to classify the different crack initiation mechanisms occurring during fatigue of this coating system (2IML coating system) and to reveal how changes in the layer architecture lead to fatigue improvement. Surface crack initiation seems to play the dominated role in the fatigue failure of this coating system as over 55% of observed cracks were surface cracks. Fatigue improvement is achieved by increasing surface initiation resistance via decreasing the IML‐Top layer thickness. However, subsurface initiation mechanisms inhibit the improvement (dominated by surface initiation mechanism) achieved by locating the IML‐Top layer closer to the top surface. Optimizing the design of 2IML multilayer coatings based on the fatigue performance should eliminate the unreacted nickel layer in the intermediate IML‐Top layer, increase the subsurface interface strength, and decrease the density of voids occurring in the annealing process. Highlights Mechanical properties of materials in layered coatings Fatigue failure mechanisms in layered coatings composed by harder and softer materials Effect of each mechanism on fatigue performance with varying architectural parameters
ISSN:8756-758X
1460-2695
DOI:10.1111/ffe.13649