Cyclic Stability of Ni44.8Cu5Ti45.2Hf5 and Zr‐Substituted Ni44.8Cu5Ti40.2Hf5Zr5 Medium‐Entropy Shape Memory Alloys. Issue 10 (14th June 2022)

• Record Type: Journal Article
• Authors: Baradari, Sadjad; Resnina, Natalia; Belyaev, Sergey; Nili-Ahmadabadi, Mahmoud
• Is Part Of: Advanced engineering materials. Volume 24:Issue 10(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-06-14
• Subjects: cyclic stability -- martensitic phase transformation -- medium-entropy alloys (MEAs) -- pseudoelasticity -- shape memory alloys; Materials -- Periodicals; 620.11
• DOI: 10.1002/adem.202200106
• Languages: English
• ISSNs: 1438-1656

Abstract

Abstract : An experimental investigation on the cyclic stability of solutionized Ni44.8 Cu5 Ti45.2 Hf5 and Zr‐substituted Ni44.8 Cu5 Ti40.2 Hf5 Zr5 (atomic percent, at%) medium‐entropy shape memory alloys (MESMAs) was carried out. The shift of the peak temperature for the forward B2 → B19′ transformation in Ni44.8 Cu5 Ti45.2 Hf5 alloy after 50 differential scanning calorimetry (DSC) cycles was measured to be 23 °C, substituting 5 at% Zr for Ti increased it to 41 °C. No residual strain accumulation was observed in Ni44.8 Cu5 Ti45.2 Hf5 alloy after 10 thermal cycles under a tensile stress of 200 MPa, and meanwhile the shape memory strain increased from 5% to 6.5%. A pseudoelastic strain ( ε PE ) of ≈2.7% was obtained in Zr‐substituted Ni44.8 Cu5 Ti40.2 Hf5 Zr5 alloy at 55 °C ( A f + 10 °C) for a maximum deformation ( ε max. ) of 4.4%. In addition, the stability of pseudoelasticity in Ni44.8 Cu5 Ti40.2 Hf5 Zr5 alloy during 100 loading–unloading cycles was examined in the solution annealed (1000 °C for 1 h) and aged (400 °C for 1 h) conditions. The results showed that aging treatment could effectively retard the degradation of pseudoelasticity in the alloy. These preliminary findings suggest that the idea of increasing chemical complexity in NiTi‐based SMAs holds promising potential in developing novel SMAs with enhanced cyclic stability. Abstract : Cyclic stability of solutionized Ni44.8 Cu5 Ti45.2 Hf5 and Ni44.8 Cu5 Ti40.2 Hf5 Zr5 (atomic percent, at%) medium‐entropy shape memory alloys is investigated during different testing modes: stress‐free thermal cycling, thermal cycling under a constant stress, and isothermal loading–unloading cycling. The idea of increasing chemical complexity in NiTi‐based SMAs holds promising potential in developing novel SMAs with enhanced cyclic stability.