Partner: J. Dutkiewicz

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

Recent publications
1.Chmielewski M., Nosewicz S., Pietrzak K., Rojek J., Strojny-Nędza A., Mackiewicz S., Dutkiewicz J., Sintering Behavior and Mechanical Properties of NiAl, Al2O3, and NiAl-Al2O3 Composites, Journal of Materials Engineering and Performance, ISSN: 1059-9495, DOI: 10.1007/s11665-014-1189-z, Vol.23, No.11, pp.3875-3886, 2014
Abstract:

It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite’s stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

Keywords:

ceramics, composites, electron, intermetallic, metallic matrix, microscopy, powder metallurgy, sintering, structural

Affiliations:
Chmielewski M.-Institute of Electronic Materials Technology (PL)
Nosewicz S.-IPPT PAN
Pietrzak K.-other affiliation
Rojek J.-IPPT PAN
Strojny-Nędza A.-Institute of Electronic Materials Technology (PL)
Mackiewicz S.-IPPT PAN
Dutkiewicz J.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
2.Pieczyska E.A., Dutkiewicz J., Masdeu F., Luckner J., Maciak R., Investigation of thermomechanical properties of ferromagnetic NiFeGa shape memory alloy subjected to pseudoelastic compression test, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.56, No.2, pp.401-408, 2011
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.-other affiliation
Luckner J.-IPPT PAN
Pieczyska E.A.-IPPT PAN