Experimental Analysis of NiTi Alloy during Strain-Controlled Low-Cycle Fatigue

• Published in: Materials Vol. 14; no. 16; p. 4455
• Main Authors: Lima, Pedro Cunha, Rodrigues, Patrícia Freitas, Ramos, Ana Sofia, da Costa, José D M, Braz Fernandes, Francisco Manuel, Vieira, Maria Teresa
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 09-08-2021; MDPI
• Subjects: Alloys; Deformation; Electrical resistivity; Intermetallic compounds; Investigations; Low cycle fatigue; Martensite; Martensitic transformations; Metal fatigue; Nickel base alloys; Nickel titanides; NiTi; resistivity; shape memory alloy; Shape memory alloys; Strain; stress-induced martensite; Superelasticity; Temperature; Wire; shape memory alloy; NiTi; stress-induced martensite; resistivity
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14164455

The interaction between the stress-induced martensitic transformation and resistivity behavior of superelastic NiTi shape memory alloy (SMA) was studied. Strain-controlled low-cycle fatigue up to 6% was monitored by in situ electrical resistivity measurements. The experimental results show that a great motion of martensite fronts results in a significant accumulation of defects, as evidenced by transmission electron microscopy (TEM), before and after the tensile cycles. This gives rise to an overall increase of the resistivity values up to the maximum deformation. Therefore, the research suggests that shape memory alloy wire has great potential as a stress sensor inside bulk materials.