Fatigue Crack Propagation In Cold Sprayed Metallic Coatings

Fatigue crack propagation in high-pressure cold-sprayed Ni, Ti and Cu was measured. For the testing, miniature single edge notched specimens of dimensions 4x3x32 mm were cut out from the coatings. The testing was carried out using pure resonance bending setup in the near-threshold and Paris regime at load ratio R ~ -1. Fatigue crack length was estimated using the differential compliance method. The morphology of the specimens' fracture surfaces was related to individual phases of the crack propagation, represented in Kmax - da/dN curves. Microstructural features defining the crack growth behavior were studied metallographically. Further, dynamic Young’s modulus of the materials was estimated from resonance frequencies of the tested samples.