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Registration Number

0215U001489, 0110U004789 , R & D reports

Title

High-frequency fatigue of metallic glass investigations.

Head

Bakai Aleksandr Stepanovich, Доктор фізико-математичних наук

Registration Date

04-03-2015

Organization

National Science Center "Kharkiv Institute of Physics and Technology

Description

In 2014 a study of the mechanisms of high-alloy fatigue nanokristalinoho VT1-0 and bulk metallic glass (OMC) on cylindrical samples Zr41.2Ti13.8Cu10.0Ni12.5Be22.5 to identify the nature of the structural changes occurring under the influence of high-frequency oscillatory loads. Analysis of the resulting database and the results of the previous phases of the project made it possible to draw some conclusions: local slip under the influence of cyclic stresses lead to irreversible changes in the structure mizhklasternyh boundaries, leading to a decrease in strength; power absorbed in areas slippage during ultrasonic treatment (UST) several orders of magnitude higher than the low-frequency tests; high-frequency fatigue OMC is a multistage process; In the beginning there is a local heating and birth vacancies in layers slip, leading to faster diffusion range order changes and partial crystallization CBOs. This MC locally znemitsnyuyetsya occur multiple nucleation slip bands and crack initiation, propagation and mergers which results in the destruction of the material. Feature of fatigue testing under compressive stresses is that there are three modes of testing: when compressed, uncompressed and compressed deformation half. Was first detected new fashion high-frequency fatigue when not compressed edge design - half-compressed mode of deformation. With limited deformation friction between the rod and squeezing the upper and lower ends are so large that the sample in these areas in compression can expand in the transverse direction, despite the positive value of Poisson's ratio. At half compressed deformation only on one end friction prevents the expansion of its transverse compressive. Size roztyahuvalne radial stress at the axial compressive stress is (- Poisson's ratio, which in zirconium-based OMS is approximately equal to 0.35), and the opposition, which is generated by the friction force is equal to (- coefficient of friction). This shows that the compressed deformation occurs at the end if. Of course deformation conditions at both ends of the same, if not specifically change the coefficients of friction at the ends. However, the high-frequency cyclic load applied to the upper end, there is a local heating and reducing the coefficient of friction, so that the upper end of the condition and deformation ceases to be stesnenoyu. This changes the type of fatigue: roztyahuvalne cyclic stress, compressed at the bottom leads to fatigue the sample is destroyed along the axis of a smooth fracture surfaces. At low power density fatigue tests released through internal friction estimated three orders of magnitude lower, making it difficult to detect this type of destruction

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Бакай Олександр Степанович
Бакай Сергій Олександрович
Михайловський Ігор Михайлович
Петрусенко Юрій Тимофійович
Щерецький Олександр Анатольйович