INFLUENCE OF MILLING PARAMETERS ON PARTICLE SIZE AND MICROHARDNESS OF CRYOMILLED AND SPARK PLASMA SINTERED CP TI

1 KOZLÍK Jiří
Co-authors:
2 BECKER Hanka 1 STRÁSKÝ Josef 1 HARCUBA Petr 1 JANEČEK Miloš
Institutions:
1 Charles University in Prague, Department fo Physics of Materials, Prague, Czech Republic, EU Jiri.Kozlik@seznam.cz
2 TU Bergakademie Freiberg, Institute of Materials Science, Freiberg, Germany, EU
Conference:
25th Anniversary International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, May 25th - 27th 2016
Proceedings:
Proceedings 25th Anniversary International Conference on Metallurgy and Materials
Pages:
1439-1444
ISBN:
978-80-87294-67-3
ISSN:
2694-9296
Published:
14th December 2016
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
66 views / 13 downloads
Abstract

Ultra-fine grained (UFG) materials are in the spotlight because of their enhanced mechanical properties. UFG material can be prepared by bottom-up process consisting of agglomeration of nano-particles or by top-down process of severe plastic deformation (SPD) In this study, Ti Grade 2 powder underwent attritor milling in liquid nitrogen (LN) and argon (LAr) and was consequently consolidated via spark plasma sintering (SPS). The influence of milling liquid (LN vs. LAr), of milling balls material (stainless steel vs. tungsten carbide) and of other milling parameters (e.g. speed, duration) on size and shape of powder particles, chemical contamination and microhardness was investigated. Particle size reduction was generally not observed, while their morphology changed significantly due to simultaneous disintegration and intensive cold welding during the milling process. Using LN as a cooling medium resulted in very high nitrogen content (up to 3 wt.%), and consequent embrittlement and hardening with microhardness values attaining 800 HV. LAr seems to be more suitable for milling of titanium, but a process control agent (stearic acid) must be added to prevent excessive cold welding. Microhardness of material without nitrogen contamination rose from original 178 HV to 200–300 HV range, depending on milling efficiency.

Keywords: Titanium, cryomilling, spark plasma sintering, contamination, microhardness

© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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