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An experimental and theoretical study of fracture mechanisms of the AMg6 alloy at different structural levels was carried out under consecutive dynamic and fatigue tests associated with conventional catastrophic events of aircraft engine components (fan blades) due to the foreign object damage and the life-time decrease in the presence of a corrosive environment. The AMg6 alloy samples were preloaded dynamically using the split Hopkinson-Kolsky bar at the strain rates ∼103 s−1 and then subjected to the VHCF test up to 108–109 cycles at the Shimadzu USF-2000 resonance testing machine (the load frequency is 20 kHz) with the cooling by abundant compressed-air and salt fog (3% NaCl). The scaling analysis of fracture surface roughness was conducted to characterize quantitatively specific areas associated with the stages of damage-failure transition in the presence of the corrosion.

The phenomenon of plastic strain localization in alloys under dynamic loading was experimentally studied on a Hopkinson–Kolsky bar and during target penetration tests. The temperature fields generated during deformation were studied in situ using a CEDIP Silver 450M high-speed infrared camera with the aim to identify the characteristic stages of localized shear. The temperature field distribution obtained at different time allowed us to trace the evolution of plastic strain localization. Microstructural analysis of the post-test samples was carried out using an optical interferometer-profilometer and electron microscopes. The structural analysis provided evidence for the correlated behavior of the ensemble of defects, which can be classified as a structural transition responsible for the strain localization. The results of experimental studies, the study of the deformed sample structure, as well as the data of numerical simulation made with consideration for the evolution of microdefects in the material, suggest that one of the mechanisms of plastic strain localization in alloys under high-speed loading is caused by jump-wise processes in the defective structure of materials.

Experimental studies on the response of samples to dynamic loading were performed using a split Hopkinson-Kolsky bar and in a series of perforation tests. In-situ investigations of the thermodynamics of deformation processes made it possible to identify the characteristic deformation localization stages. Temperature fields were recorded with a high-speed infrared camera CEDIP Silver 450M, and strain localization in the samples was evaluated with a strain noninvasive measurement system StrainMaster. Temperature measurements made in the localization zone did not support a generally accepted concept that the strain localization mechanism is the mechanism governed by thermoplastic instability. The microstructural analysis of the samples stored after the experiment was carried out using an optical interferometer-profilometer and a scanning electron microscope. The analysis revealed the correlated behavior of the ensemble of defects, which can be classified as a structural transition providing strain localization. The data of experimental studies, the examination of the structure of deformed samples, as well as the data of numerical modeling performed with consideration of the kinetics of accumulation of microdefects in the material suggest that one of the mechanisms of plastic strain localization at high loading rates is associated with the jump-like processes in the defect structure of the material.