Shape memory alloys (SMA) are intermetallic compounds that exhibit extraordinary thermo-mechanical properties such as: the superelasticity and the shape memory effect. SMA functional performances are correlated to the composition as well as the microstructure induced during the material processing. For the developing of SMA components for practical applications all the processing steps, melting, hot and cold working and final training have to be controlled strictly to guarantee the programmed smart characteristics.
This research is based on the last two decades experience in the field of SMA and is particularly focussed on:
the production and characterization of several SMA systems: NiTi, NiTiX (X= Cu, Zr, Hf, Y, Er) , CuZn based, CuZn based, CuZr based, Ni3Ta based and quaternary compounds for improving functional properties (transformation temperatures, recovery strain, damping capacity, generated forces);
the investigation of innovative methods for SMA processing and training. In addition to traditional shape setting methods, ad hoc systems are developed. Furthermore fiber laser technology is applied for innovative heat treatments and shape setting of NiTi compounds. Fast current pulses (10 ms) method was are experimented for final thin wires shape setting. A new method for improving SMA actuators forces based on High Performance Shape Memory Effect (HP-SME) is applied to NiTi wires and laser catted components for new class of high performances NiTi actuators.
the production and characterization of FerroMagnetic Shape Memory Alloys (FeSMA) and Magnetocaloric alloys. Polycrystalline materials are prepared and characterized; from the principal NiMnGa compound to quaternary compounds such as NiMnGaCo. Furthermore, microstructural and functional characterizations of single crystals, melt spun ribbons and thin films are carried out on NiMnGa, CoNiGa, NiFeAl, NiFeGa, NiFeGaCo, NiMnIn, NiMnSn (Co,Cu), NiMnInCo.
CNR Lecco Unit can supply SMA alloys material batches (on pilot scale production) as well as high purity “targets” for thin film deposition processes.
shape memory alloys nitinol NiTi NiMnGa HTSMA FeSMA HPSME
R. Casati, M.Vedani, A.Tuissi
Thermal cycling of stress induced martensite for High Performance Shape Memory Effect
Scripta Materialia (80) 1-16 (2014)
R Casati, CA Biffi, M Vedani, A Tuissi
High Performance Shape Memory Effect in Nitinol wire for actuators with increased operating temperature range
Functional Materials Letters 7 (5), 1450063 (2014)
C Maletta, E Sgambitterra, F Furgiuele, R Casati, A Tuissi
Fatigue properties of a pseudoelastic NiTi alloy: Strain ratcheting and hysteresis under cyclic tensile loading
International Journal of Fatigue 66, 78-85 (2014)
A.Nepoli, F. Passaretti, E. Villa
Phase transition and mechanical damping properties: a DMTA study of NiTiCu shape memory alloys
Intermetallics 32, 394-400, (2013)
Nespoli, E. Villa, F. Passaretti
Effect of Yttrium on microstructure, Thermal Properties and damping capacity of Ni41Ti50Cu9 alloy
Journal of Alloys and Compounds, 653, 234-242, (2015)
P Ranzieri, S Fabbrici, L Nasi, L Righi, F Casoli, V A. Chernenko, E Villa, F Albertini
Multiscale investigation of epitaxial Ni-Mn-Ga/MgO(100) thin films with thickness ranging from 10 to 100 nm
Acta Materialia, Vol. 61, Issue 1, 263-272, (2013)
- R. Casati, M.Vedani, A.Tuissi
- Politecnico di Milano
- Università della Calabria
- CNR IMEM
- BCMaterials & Dpto de Electricidad y Electronica Universidad del Pais Vasco di Bilbao