Source: https://lettersonmaterials.com/en/Readers/Article.aspx?aid=1225
Timestamp: 2019-04-23 08:05:58+00:00

Document:
Effect of ultrasonic treatment (UST) on the microstructure and microhardness of ultrafine grained nickel processed by high pressure torsion (HPT) was studied. With this aim, samples after HPT were subjected to oscillating compression-tension stresses with amplitudes 15, 30, 45, 60 and 90 MPa in the zone of strain antinode of an ultrasonic instrument. The microstructure of initial and ultrasonically treated samples was studied by X-ray diffraction analysis, transmission electron microscopy and electron back-scatter diffraction (EBSD). Dependences of average dislocation density, internal strains and microhardness on the ultrasound amplitude were obtained. At lower amplitudes (15, 30 MPa) UST leads to some increase of microhardness, internal stresses and dislocation density. At amplitude 60 MPa a considerable reduction of all mentioned characteristics as compared to the initial state occurs, while with a further increase of the amplitude to 90 MPa they exhibit a back increase. An increase of the fraction of high-angle boundaries without a significant change in the average grain size also occurs after UST. The regularities observed are explained as follows. With an increase of ultrasound amplitude, generation and accumulation of dislocations in the grains occur first. Then the processes of their passing through grain boundaries and rearrangement are activated that results in an increase of misorientations of the grains, more effective screening of dislocation stress fields and stress relaxation. With further increase of the stress amplitude processes of generation and accumulation of dislocations prevails over the processes of their annihilation and rearrangement, so that the relaxation effect weakens and diminishes.
1. Yu. R. Kolobov, O. A. Kashin, E. F. Dudarev et al. Russian Phys. J. 43 (9), 754 (2000) (in Russian). [Ю. Р. Колобов, О. А. Кашин, Е. Ф. Дударев и др. Изв. вузов. Физика. 9, 45 (2000)].
2. A. V. Panin, E. A. Melnikova, O. B. Perevalova, et al. Fiz. mezomekh 12 (1), 83 (2009) (in Russian). [А. В. Панин, Е. А. Мельникова, О. Б. Перевалова и др. Физ. мезомех. 12 (1), 83 (2009)].
3. M. M. Myshlyaev, V. V. Shpeizman, V. V. Klubovich et al. Phys. Solid State 57 (10), 2039 (2015). [М. М. Мышляев, В. В. Шпейзман, В. В. Клубович и др. ФТТ, 57 (10), 1986 (2015)].
4. Y. Han, Ke Li, J. Wang et al. Mater. Sci. Eng. A 405 (1-2), 306 (2005).
5. V. V. Rubanik Jr., V. V. Rubanik, V. V. Klubovich. Mater. Sci. Eng. A 481 - 482, 620 (2008).
6. A. A. Nazarov, R. R. Mulyukov. In: Handbook of Nanoscience, Engineering, and Technology, Ed. W. Goddard, D. Brenner, S. Lyshevski, G. Iafrate, CRC Press. 2003, p. 22 - 1.
7. R. Z. Valiev, A. P. Zhilyaev, T. G. Langdon. Bulk Nanostructured Materials: Fundamentals and Applications. Hoboken, Wiley. (2013) 440 p.
8. N. A. Tyapunina, V. V. Blagoveschenskiy, G. M. Zinenkova, Yu. A. Ivashkin. Inzestiya Vuzov. Fizika 6, 118 (1982) (in Russian). [Н. А. Тяпунина, В. В. Благовещенский, Г. М. Зиненкова, Ю. А. Ивашкин. Изв. вузов. Физика. 6, 118 (1982)].
9. S. V. Dmitriev, A. I. Pshenichnyuk, A. M. Iskandarov, A. A. Nazarova. Modelling Simul. Mater. Sci. Eng. 18, 025012 (2010).
10. D. V. Bachurin, R. T. Murzaev, Yu. A. Baimova, A. A. Samigullina, K. A. Krylova. Letters on Materials 6, 183 (2016) (in Russian). [Д. В. Бачурин, Р. Т. Мурзаев, Ю. А. Баимова, А. А. Самигуллина, К. А. Крылова. Письма о материалах 6, 183 (2016)].
11. A. A. Nazarov, Sh. Kh. Khannanov. Fizika i khimiya obrabotki materialov 4, 109 (1986) (in Russian). [А. А. Назаров, Ш. Х. Ханнанов. Физ. химия обр. матер. 4, 109 (1986)].
12. A. A. Nazarova, R. R. Mulyukov, V. V. Rubanik et al. Phys. Metals Metallogr. 110 (6), 574 (2010). [А. А. Назарова, Р. Р. Мулюков, В. В. Рубаник и др. ФММ, 110 (6), 600 (2010)].
13. A. A. Samigullina, Yu. V. Tsarenko, V. V. Rubanik, et al. Letters on Materials 2, 214 (2012). [А. А. Самигуллина, Ю. В. Царенко, В. В. Рубаник и др. Письма о материалах 2, 214 (2012)].
14. A. A. Samigullina, A. A. Nazarov, R. R. Mulyukov et al. Rev. Adv. Mater. Sci. 39, 48 (2014).

References: V. 
 V. 
 V. 
 V. 
 V. 
 V. 
 V. 
 V. 
 V. 
 V. 
 V. 
 V.