Scopul nostru este sprijinirea şi promovarea cercetării ştiinţifice şi facilitarea comunicării între cercetătorii români din întreaga lume.
Autori: Nicoleta Monica Lohan, Bogdan Pricop, Leandru-Gheorghe Bujoreanu, Nicanor Cimpoesu,
Editorial: International Journal of Materials Research, 102(11), p.1345-1351, 2011.
Different fragments of martensitic Cu-14.86 Zn-5.81 Al-0.5 Fe (mass. %) shape memory alloy
were subjected to heating, up to 453 K, with different rates ranging from 1 K×1.66×10 2 s 1 to
54.6×1.66×10 2 s 1, performed by means of a differential scanning calorimeter. In all cases, during
heating, an endothermic peak was observed which was associated with the martensite reversion to
parent phase. By means of the differential scanning calorimeter charts the critical transformation
temperatures of martensite reversion were determined using the tangent method. The effects of
heating rate were evaluated from the point of view: (i) of variation tendencies of critical
transformation temperatures; (ii) of deviations of experimental values from linear fit and extrapolation
to zero heating rate and (iii) of corroborating morphological changes of martensite (sub)plates with
heat flow variation particularities. The results prove that there is an obvious tendency of critical
transformation temperatures, of reverse martensitic transformation, to linearly increase with heating
rate. The effectiveness of the linear relationships was checked for two heating rate values located
inside and outside above mentioned range, respectively and the difference between the experimental
and calculated values of critical transformation temperatures felt within the range (-3 … +4) ‰.
Cuvinte cheie: Shape memory alloys, Differential scanning calorimetry, Phase transformation, Critical transformation temperature, Heating rate effects, Linear regression