Search academic texts

Information × Registration Number 0213U006426, 0110U004789 , R & D reports Title High-frequency fatigue of metallic glass investigations. popup.stage_title Head Bakai Aleksandr Stepanovich, Доктор фізико-математичних наук Registration Date 11-06-2013 Organization National Science Center "Kharkiv Institute of Physics and Technology popup.description2 n 2012, a study of mechanisms of high-frequency fatigue bulk metallic glass and its impact on the tapes with thickness of 50 mm alloy Zr46.8Ti8.2Cu7.5Ni10Be27.5. Structural and phase changes in the material, occurring under the influence of ultrasonic waves (20 kHz, the amplitude of 8-15 microns) were studied by X-ray diffraction and high-resolution microscopy. In addition, measurements of electrical resistance changes, the elastic moduli, the damping of mechanical oscillations (internal friction) and calorimetric methods performance DMA and DSC. Found that the effect of ultrasound on the structure of the belt accumulates with increasing exposure (from 30 to 300 seconds) and leads to a reduction of the elastic moduli, the growth of the internal friction and reduce the heat of crystallization of glass with a gradual annealing. For the electrical characteristic of the monotony and not dependent on the course of high deformation. Typical is the decline of the electrical after about 50 second exposure, followed by its significant growth, reaching about 20%. However, for large exposures, as shown in some samples resistivity begins to decrease, as a partial (7%) crystallization of the tape. In other samples where no-observed visible crystallization, electrical resistance increased with exposure time. With this method, high-resolution electron microscopy, and elemental analysis failed to detect a significant defect formation and crystallization in the bulk feed. This leads to the conclusion that the main structural changes occur in the surface layers of the tape where the roughness is the local concentration of the applied voltage. To identify the mechanisms of high-frequency fatigue study of the microscopic structure of bulk metallic glass Zr46.8Ti8.2Cu7.5Ni10Be27.5 methods high definition emissionoi field microscopy. The main result of these experiments is to identify a cluster of glass structure with a scale of clusters of ~ 10 nm. The first time that intercluster boundaries combine two features. First, they have a substantial compositional stratification that marks the formation phase of sweating and partial phase separation. Second, there are narrow intercluster atomic structure-disordered boundary, ie, two-dimensional topological defects. The results of these structural studies suggest that it is sliding on the intercluster boundaries under the influence of high-frequency AC voltage is the main mechanism for the absorption of vibration energy that over time leads to a partial crystallization of the material and the initiation and propagation of microcracks. Product Description popup.authors Бакай Олександр Степанович Бакай Сергій Олександрович Михайловський Ігор Михайлович Петрусенко Юрій Тимофійович Щерецький Олександр Анатольйович popup.nrat_date 2020-04-02 Close