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Autori: G. Vitel, A. L. Paraschiv, M. G. Suru, N. Cimpoesu, L.-G. Bujoreanu
Editorial: Optoelectronics and Advanced Materials-Rapid Communications, 6(1-2), p.339-342, 2012.
A normalized hot forged Cu-15Zn-6Al (mass. %) shape memory alloy (SMA) was subjected to tempering heat treatments meant to enhance the reversion to parent phase (austenite) of thermally induced martensite. By means of differential scanning calorimetry (DSC) the reversibility of martensitic transformation was verified during constant-rate heating-cooling cycles. The results have showed that 373 K- tempering destabilized martensite and enabled its reversion at lower temperatures, on heating. Conversely, 473 K-tempering caused the disappearance of martensite phase. The structural features, observed both by optical microscopy (OM) and by scanning electron microscopy (SEM), at the phase transformation product obtained after 473 K-tempering suggest the presence transitory bainite, since its nucleation is diffusionless while its growth is diffusion controlled, which could explain the lack of reversibility.
Cuvinte cheie: Cu-Zn-Al shape memory alloy, Martensite, Thermal cycle, Differential scanning calorimetry, Heat treatment