Study of the Microstructure, Crystallographic Structure and Thermal Stability of Al–Ti–Nb Alloys Produced by Selective Electron Beam Alloying
| Autor: | A. Beskrovnyi, D. P. Kozlenko, R. Bezdushnyi, D. Neov, Peter G. Petrov, S. Valkov |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Materials science Scanning electron microscope Neutron diffraction Intermetallic Analytical chemistry chemistry.chemical_element 02 engineering and technology Crystal structure 021001 nanoscience & nanotechnology Microstructure 01 natural sciences Thermal expansion Surfaces Coatings and Films chemistry Aluminium 0103 physical sciences Thermal stability 0210 nano-technology |
| Zdroj: | Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques. 12:436-441 |
| ISSN: | 1819-7094 1027-4510 |
| DOI: | 10.1134/s1027451018030187 |
| Popis: | This paper aims an investigation of the microstructure and crystallographic structure as well as the thermal stability of Al–Ti–Nb formed by selective electron beam surface alloying. The fabrication of the samples has been carried out using circular sweep mode, as two velocities of the sample movement have been chosen: V1 = 1 cm/s and V2 = 0.5 cm/s. The studied microstructure and crystallographic structure have been investigated by X-ray diffraction (XRD) and Scanning electron microscopy (SEM) respectively. The thermal behavior of the obtained surface alloys are evaluated by the coefficient of thermal expansion (CTE) which has been evaluated by neutron diffraction measurements at high temperature. The results show that in the earlier stages of formation, the microstructure of the intermetallic phase is mainly in the form of coarse fractions, but at the following moments they dissolve, forming separated alloyed zone and base Al substrate as the alloyed zone consists of fine (Ti,Nb)Al3 particles dispersed in the Al matrix with small amount of undissolved intermetallic fractions. Formation of preferred crystallographic orientation as a function of the speed of specimen motion has not been observed. The performed neutron diffraction measurements show that the lattice parameters of the obtained intermetallic (Ti,Nb)Al3 are less upshifted in comparison to pure Al. It has been found that the aluminium lattice is much more unstable at high temperatures than that of the intermetallic phase. The CTE for the intermetallic phase is 8.70 ppm/K for a axis and 7.75 ppm/K for c axis respectively while considering Al it is 12.95 ppm/K. |
| Databáze: | OpenAIRE |
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