INCREASE OF THE FATIGUE DURABILITY OF LIGHT ALLOYS BY ELECTRON BEAM TREATMENT

Most of the metals and alloys performance characteristics are determined by the structural phase state of the surfacelayers. These characteristics can be significantly improved by surface hardening. Silumin of the eutectic compositionAK12 and technically pure titanium of the VT1-0 grade were treated by a high-intensity pulsed electron beam in various modes. Many-cycle fatigue tests were carried out and irradiation modes were revealed, which made it possible to increase significantly the fatigue life of the materials under study. Using the methods of scanning and transmission electron
diffraction microscopy, we studied the structural-phase states and defective substructure of silumin and titanium, subjected to multi-cycle fatigue tests to their failure. It was revealed that irradiation of the silumin surface with a high-
intensity pulsed electron beam with electron energy parameters 18 keV, ES = 20 J/cm2, τ = 150 μs, N = 5 pulses, f = 0.3 s–1 allows its fatigue life to be increased 3.5 times. The main reasons for the multiple increase in the fatigue life of silumin are the formation of a multiphase submicro- and nanoscale structure in the surface layer, and the grinding of large silicon wafers to a nanoscale state. The physical reasons for the 2.2-fold increase in the fatigue life of technically pure titanium after electron-beam treatment according to the mode (electron energy 16 keV, ES = 25 J/cm2, τ = 150 μs, N = 3 pulses,
f = 0.3 s–1) are the formation of a lamellar substructure due to high-speed crystallization of the titanium surface layer and a more than twofold decrease in the scalar dislocation density.

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