Specific forward/reverse latent heat and martensite fraction measurement during superelastic deformation of nanostructured NiTi wires

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:774

Article

de Oliveira, Henrique Martinni Ramos¹  Louche, Herve²  Grassi, Estephanie Nobre Dantas¹  Favier, Denis¹ 

[1] Univ Grenoble Alpes, CNRS, Grenoble INP, TIMC IMAG, F-38000 Grenoble, France

[2] Univ Montpellier, CNRS, LMGC, Montpellier, France

关键词: Superelastic NiTi;    Nanostructured NiTi wires;    Kinematic and thermal full field measurements;    Heat balance;    Enthalpy of transformation;   

DOI  :  10.1016/j.msea.2020.138928

来源: Elsevier

【 摘 要 】

This study analyses the thermomechanical tensile behaviour of a cold drawn Ti-50.9at.%Ni wire submitted to heat treatment at 598 K for 30 min, which is below the recrystallization temperature (623 K). Such low temperature heat treatment induces a superelastic loop without a stress plateau. However, the absence or weakness of peaks on its differential scanning calorimetry prevents the determination of specific latent heat. This is a common effect of nanostructured materials such as superelastic wires. A method using strain and temperature field measurements was developed and used to determine thermal power and thermal energy during superelastic tensile tests through a heat balance. From these results and using a thermodynamic approach, forward and reverse specific latent heat and the martensite fraction are estimated as a function of strain and stress.

【 授权许可】

Free