On the thermodynamics of the martensitic transformations in Ti-rich Ni-Ti-Co thin films: frictional work and stored elastic energy

B. MALVASIO; ISOLA, LUCIO M.; GIORDANA, M. FLORENCIA; MALARRÍA, JORGE A.

Congreso; International Conference on Martensitic Transformation; 2022

ICOMAT

A critical review of the thermodynamics ofthermally-induced thermoelastic martensitic transformations ispresented, in order to investigate the wide-spread multipletransformation producedby Ti2Ninano-precipitates in Ti-rich Ni-Tishape memory alloys. For this purpose, a series of amorphous Ti-Ni-Cothin films with the same composition were crystallized at differenttemperatures. The characteristic temperatures and heat of thetransformations were measured by four-point probe resistivity anddifferential scanning calorimetry. The change in the values of thefrictional work and the stored elastic energy due to theredistribution of the Ti2Niprecipitates were assessed from the transformation temperatures, andrelated with the transformation heats measured in the samplesannealed at different temperatures. The influence of the dissipationof the stored elastic energy on the transformation temperatures andthermal hysteresis is discussed. Finally, the wide-spread multipletransformation is understood as an effect of the local stressesintroduced by Ti2Ninano-precipitates in the matrix.p { margin-bottom: 0.25cm; direction: ltr; color: #000000; line-height: 115%; orphans: 2; widows: 2 }p.western { font-family: "Liberation Serif", "Times New Roman", serif; font-size: 12pt; so-language: en-US }p.cjk { font-family: "Noto Sans CJK SC"; font-size: 12pt; so-language: zh-CN }p.ctl { font-family: "Lohit Devanagari"; font-size: 12pt; so-language: hi-IN }