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Particularities of phase transitions in thermomechanically processed Cu-Al-Mn shape memory alloys

Domenii publicaţii > Stiinte ingineresti + Tipuri publicaţii > Articol în volumul unei conferinţe

Autori: S. Stanciu, L. G. Bujoreanu, R.I.Comãneci, N. Cimpoeşu, I. Ioniţã, V.V.Moldoveanu

Editorial: P. ©ittner, L. Heller and V. Paidar, EDP Sciences , ESOMAT 2009 - The 8th European Symposium on Martensitic Transformations, DOI:10.1051/esomat/200905004, p.05004, 2009.

Rezumat:

The thermally and stress induced phase transitions occurring in a Cu-Al-Mn Shape Memory Alloy (SMA)
have been investigated by means of thermal analysis techniques, tensile testing and microscopic observations. On
heating a hot rolled solution annealed Cu-Al-Mn SMA, up to 873 K, two phase transformations, related to
equilibrium phase precipitation and to 2-step order-disorder transition, respectively, were revealed by Differential
Scanning Calorimetry (DSC). During tensile testing, the Cu-Al-Mn SMA under study experienced almost complete
superelasticity, after five mechanical training cycles, as well as good ductility and tensile resistance. On trained
specimens the formation of stress induced martensite was revealed by optical microscopy (OM) observations. The
reversion to austenite of stress induced martensite was accompanied by relatively large increases of elastic modulus
and internal friction, determined on Dynamic Mechanical Analyzer (DMA) and by marked variations of relative
elongation, thermal expansion coefficient and elongation rate, determined by dilatometry. Since it is a two step
transition, it was associated with the two morphologies of stress induced martensite observed by Scanning Electron
Microscopy (SEM).

Cuvinte cheie: shape memory alloy, DSC, tensile testing, optical microscopy, DMA

URL: www.esomat.org