Microstructure and Thermal Analyses of Cu87-xAl13Nbx High-Temperature Shape Memory Alloys

• Published in: Materials research (São Carlos, São Paulo, Brazil) Vol. 22; no. suppl 1
• Main Authors: Simões, Jackson de Brito, Pereira, Endira Maria Araújo, Santiago, José Joelson de Melo, Araújo, Carlos José de
• Format: Journal Article
• Language: English
• Published: ABM, ABC, ABPol 01-01-2019; Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)
• Subjects: Cu-Al-Nb alloys; ENGINEERING, CHEMICAL; high-temperature shape memory alloys; MATERIALS SCIENCE, MULTIDISCIPLINARY; METALLURGY & METALLURGICAL ENGINEERING; phase martensitic transformation; shape memory alloy; temperatures; shape memory alloy; temperatures; Cu-Al-Nb alloys; high-temperature shape memory alloys; phase martensitic transformation
• ISSN: 1516-1439; 1980-5373; 1980-5373
• DOI: 10.1590/1980-5373-mr-2018-0849

This paper presents a thermal and microstructural characterization of Cu87-xAl13Nbx (wt%) high temperature shape memory alloys (HTSMA), with Nb contents ranging from 1 to 3%. The alloys were obtained by arc melting under argon atmosphere. Thermal characterization was performed by differential scanning calorimetry (DSC), revealing that the phase martensitic transformation of all the studied alloys occurs in the range of 200 ºC to 450 ºC. Thermal cycling in this temperature range caused the martensitic transformation to disappear after approximately 6 cycles. However, a new heat treatment at 850 ºC followed by water quenching causes the martensitic transformation to be recovered. Microstructural characterization was performed using optical microscopy (OM) and scanning electron microscopy (SEM), revealing the presence of Nb precipitates in a Cu-Al martensitic matrix, mainly in the Nb-rich compositions. These different microstructures with Nb particles cause a hardness variation that initially decreases between 0.5 %Nb (275HV) and 1.0 %Nb (225HV), then increasing continuously up to 3.0% Nb (380HV).