Hydrogen and its effect on the grinding of Ti-Ni powder

OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 23 No. 3 2021 Hydrogen and its effect on the grinding of Ti-Ni powder Ekaterina Abdulmenova a, * , Sergey Kulkov b Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences, 2/4 pr. Akademicheskii, Tomsk, 634055, Russian Federation a https://orcid.org/0000-0002-9594-5706, Ekaterina.V.Abdulmenova@yandex.ru, b https://orcid.org/0000-0002-4635-6569, kulkov@ispms.ru Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2021 vol. 23 no. 3 pp. 100–111 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2021-23.3-100-111 Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov ARTICLE INFO Article history : Received: 07 April 2021 Revised: 23 April 2021 Accepted: 30 July 2021 Available online: 15 September 2021 Keywords : Ni-Ti powder Mechanical treatment Hydrogenation Hydrogen Coherently diffracting domain Lattice parameter Phase composition Funding The results were obtained in the framework of the Integrated Project “Establishment of import-substituting high-tech full-cycle production of complex-shaped indexable carbide cutting inserts for priority industries” (Agreement No. 075-11-2019-036 dated November 27, 2019) implemented by the ISPMS SB RAS at the financial support of the Ministry of Education and Science of the Russian Federation as part of Decree of the Government of the Russian Federation No. 218 dated April 09, 2010. Acknowledgements Research were conducted at core facil- ity “Structure, mechanical and physical properties of materials”. ABSTRACT Introduction. Industrial nickel-titanium alloy PN55T45 closed to the equiatomic composition is widely used for the manufacture of products by powder metallurgy. To achieve high physical and mechanical properties of the material obtained by this method, it is necessary to use fine powders, which can be obtained by implementing high-intensity grinding in a planetary ball mill. However, during such treatment, contamination, powder oxidation and particle aggregation, etc. are possible. To solve this problem, preliminary hydrogenation is proposed for subsequent grinding in a planetary ball mill. The aim of the work is to study the effect of hydrogen on the grinding of titanium nickelide powder. Materials and methods. The morphology and average particle size of the powders were studied by scanning electron microscopy. The structure and phase composition of the powders were investigated by the methods of X-ray structural and X-ray phase analysis. The data of X-ray structural analysis were used to estimate the dislocation density. Results and discussions . It is shown that the use of pre-hydrogenation for 180 minutes before machining allows reducing the average particle size by about a half. After mechanical treatment of the powder, the parameters of the crystal lattices of the TiNi (austenite), Ti 2 Ni and Ni 3 Ti phases do not change within the error range. After mechanical treatment of the powder with preliminary hydrogenation, the crystal lattice parameter of only the Ti 2 Ni phase changes significantly, in particular, at 180 minutes of hydrogenation, the lattice parameter increases to 1.1457 ± 5×10 -4 nm, which corresponds to the stoichiometry of the Ti 2 NiH 0.5 hydride with a lattice parameter of 1.1500 nm. The highest dislocation density estimated by X-ray diffraction analysis is contained in the Ti 2 Ni (511) phase than in the TiNi (austenite) (110) and Ni 3 Ti (202) phases. Thus, preliminary hydrogenation can be an effective method of powder grinding due to the formation of brittle hydride and suppression of the aggregation of fine particles during high-intensity mechanical treatment. For citation: Abdulmenova E.V., Kulkov S.N. Hydrogen and its effect on the grinding of Ti-Ni powder . Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science , 2021, vol. 23, no. 3, pp. 100–111. DOI: 10.17212/1994-6309-2021-23.3- 100-111. (In Russian). ______ * Corresponding author Abdulmenova Ekaterina V. , Postgraduate student, Research assistant Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences, 2/4 pr. Akademicheskii, 634055, Tomsk, Russian Federation Tel .: 8 (3822) 286-988, e-mail : Ekaterina.V.Abdulmenova@ispms.ru