Shape memory alloys prepared by various methods

J. Kopeček¹, M. Jarošová², K. Jurek², L. Bodnárová³, H. Seiner³, P. Sedlák³,
M. Landa³, J. Drahokoupil¹, F. Laufek⁴, P. Novák⁵, M. Dopita⁶, V. Kopecký¹,
O. Heczko¹

¹Institute of Physics of the AS CR, Na Slovance 2, 182 21 Praha 8, Czech Republic

²Institute of Physics of the AS CR, Cukrovarnická 10/112, 162 00 Praha 6, Czech Republic

³Institute of Thermomechanics of AS CR, Dolejškova 5, 182 00 Prague 8, Czech Republic

¹Czech Geological Survey, Geologická 6, 152 00 Praha 5, Czech Republic

⁵Institute of Chemical Technology, Dept Met & Corros Engn, Technická 5, 16628 Praha, Czech Republic.

⁶Technical University Bergakademie Freiberg, Inst. Mat. Sci., D-09596 Freiberg, Germany

Shape memory alloys have been investigated for couple of last decades in IoP ASCR. Main attention has paid to investigation of the single-crystals to describe martensitic transformation properly after some years of polycrystals properties studies. Nevertheless, progress of knowledge turn attention toward applied problems as well and thus polycrystalline became investigated again. Novel procedures of powder metallurgy as spark plasma sintering (SPS), self-combustion high-temperature synthesis (SHS) and mechanical alloying are applied now.

I would like to present the compilation of recent results, which were performed on two materials. The first one is less common SMA Co₃₈Ni₃₃Al₂₉, which was studied as single crystals and SPS prepared samples. The martensitic transformation in this alloy was quite underestimated by other authors in last decades and some details of transformation kinetics are not documented even now.

The second one is the cornerstone of SMAs – the NiTi alloy here prepared by combination of SPS and SHS processes, when the ignition of SHS is done in SPS machine chamber. Such process should help the convenient preparation of Nitinol thin wires for medical applications. It can avoid the creation of particles, especially carbides, which precipitates during all casting processes as are VIM and VAR.

Authors would like to acknowledge the financial support from the Czech Science Foundation projects 101/09/0702 and 14-03044S.