Partner: T. Czeppe

Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)

Recent publications
1.Swiatek Z., Levintant-Zayonts N., Michalec M., Czeppe T., Lipinski M., Bonchyk O., Savitskij G., Creation of wear-resistant near-surface-layers with inhomogeneous structure on NiTi alloy by ion implantation technology, Physics Procedia, ISSN: 1875-3892, DOI: 10.1016/j.phpro.2010.11.077, Vol.10, pp.69-76, 2010
Abstract:

In the present study we report the changes in the modified near-surface layer on NiTi shape memory alloy, caused by ion implantation as well as their influence on the structure and mechanical properties of this material. Experimental results of an inhomogeneous structure and tribological properties of implanted NiTi are discussed in this paper.

Keywords:

shape memory NiTi alloy, Ion implantation, DSC, X-ray diffractometry, TEM

Affiliations:
Swiatek Z.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Levintant-Zayonts N.-IPPT PAN
Michalec M.-Jagiellonian University (PL)
Czeppe T.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Lipinski M.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Bonchyk O.-Ya.S. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics NASU (UA)
Savitskij G.-Ya.S. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics NASU (UA)
2.Czeppe T., Levintant-Zayonts N., Swiatek Z., Michalec M., Bonchyk O., Savitskij G., Inhomogeneous structure of near-surface layers in the ion-implanted niti alloy, VACUUM, ISSN: 0042-207X, DOI: 10.1016/j.vacuum.2009.01.066, Vol.83, No.Supplement 1, pp.S214-S219, 2009
Abstract:

This paper reports the application of nitrogen ion implantation for modification of a shape memory alloy. It is known that the problem of creating a protective surface coating for the shape memory alloy is the most acute for potential applications of this material. Thus, the problem of increasing surface protective properties and, at the same time, simultaneous preservation of functional properties of shape memory materials is a subject of research and development [Pelletier H, Muller D, Mille P, Grob J. Surf Coat Technol 2002;158:309.]. The surface characterization of nitrogen implanted (fluence 1018 cm−2 and energy 50 keV) equiatomic commercial NiTi alloy samples was performed with the assistance of high resolution transmission electron microscopy (HTEM) techniques and modifications of phase composition before and after irradiation are studied at room and martensitic transformation temperatures by X-ray diffraction methods. Differential scanning calorimetry (DSC, TA Instruments) was used to characterize the transformation sequence and transformation temperatures for the initial and surface-modified materials. Experimental results of an inhomogeneous structure of near-surface layers in the ion-implanted NiTi alloy are discussed in this paper

Keywords:

Shape memory NiTi alloy, Ion implantation, DSC, X-ray diffractometry, TEM

Affiliations:
Czeppe T.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Levintant-Zayonts N.-IPPT PAN
Swiatek Z.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Michalec M.-Jagiellonian University (PL)
Bonchyk O.-Ya.S. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics NASU (UA)
Savitskij G.-Ya.S. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics NASU (UA)
3.Dutkiewicz J.M., Maziarz W., Czeppe T., Lityńska L., Nowacki W.K., Gadaj S.P., Luckner J., Pieczyska E.A., Powder metallurgy technology of niti shape memory alloy, JOURNAL DE PHYSIQUE IV, ISSN: 1155-4339, DOI: 10.1140/epjst/e2008-00654-6, Vol.158, pp.59-65, 2008
Abstract:

Powder metallurgy technology was elaborated for consolidation of shape memory NiTi powders. The shape memory alloy was compacted from the prealloyed powder delivered by Memry SA. The powder shows Ms = 10°C and As = -34°C as results from DSC measurements. The samples were hot pressed in the as delivered spherical particle's state. The hot compaction was performed in a specially constructed vacuum press, at temperature of 680°C and pressure of 400 MPa. The alloy powder was encapsulated in copper capsules prior to hot pressing to avoid oxidation or carbides formation. The alloy after hot vacuum compaction at 680°C (i.e. within the B2 NiTi stability range) has shown similar transformation range as the powder. The porosity of samples compacted in the as delivered state was only 1%. The samples tested in compression up to ε = 0.06 have shown partial superelastic effect due to martensitic reversible transformation which started at the stress above 300 MPa and returned back to ε = 0.015 after unloading. They have shown also a high ultimate compression strength of 1600 MPa. Measurements of the samples temperature changes during the process allowed to detect the temperature increase above 12°C for the strain rate 10-2 s-1 accompanied the exothermic martensite transformation during loading and the temperature decrease related to the reverse endothermic transformation during unloading.

Keywords:

Powder metallurgy technology, shape memory alloys, DSC measurements, compression test, exothermic martensite transformation, endothermic reverse transformation

Affiliations:
Dutkiewicz J.M.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Maziarz W.-other affiliation
Czeppe T.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Lityńska L.-other affiliation
Nowacki W.K.-IPPT PAN
Gadaj S.P.-IPPT PAN
Luckner J.-IPPT PAN
Pieczyska E.A.-IPPT PAN