TY - JOUR
T1 - The effect of annealing on the mechanical properties and microstructural evolution of Ti-rich NiTi shape memory alloy
AU - Tadayyon, Ghazal
AU - Mazinani, Mohammad
AU - Guo, Yina
AU - Zebarjad, Seyed Mojtaba
AU - Tofail, Syed A.M.
AU - Biggs, Manus J.
N1 - Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2016/4/26
Y1 - 2016/4/26
N2 - An investigation was carried out into the influence of the annealing temperatures on the thermo-mechanical behavior of Ti-rich NiTi alloy with regard to transformation temperatures, mechanical properties at room temperature and microstructure evolution under deformation. It was found that annealing above the recrystallization temperature (600 °C) modulated the mechanical behavior of the alloy significantly. Based on tensile and DSC analysis, it was observed that by increasing the annealing temperature, the shape memory behavior of the alloys improved. Scanning and transmission electron microscopy were used to investigate the fracture surfaces and microstructural evolution of the NiTi samples after failure. Fractography revealed the brittle fracture area produced through the propagation of cleavage cracks; however, ductile fracture via nucleation growth and coalescence of micro-dimples in the martensitic phase at room temperature were also observed. During plastic deformation, the NiTi alloy was also observed to undergo a detwinning process, dislocation slip and the formation of submicrocrystalline grains, nanocrystallization and amorphous bands.
AB - An investigation was carried out into the influence of the annealing temperatures on the thermo-mechanical behavior of Ti-rich NiTi alloy with regard to transformation temperatures, mechanical properties at room temperature and microstructure evolution under deformation. It was found that annealing above the recrystallization temperature (600 °C) modulated the mechanical behavior of the alloy significantly. Based on tensile and DSC analysis, it was observed that by increasing the annealing temperature, the shape memory behavior of the alloys improved. Scanning and transmission electron microscopy were used to investigate the fracture surfaces and microstructural evolution of the NiTi samples after failure. Fractography revealed the brittle fracture area produced through the propagation of cleavage cracks; however, ductile fracture via nucleation growth and coalescence of micro-dimples in the martensitic phase at room temperature were also observed. During plastic deformation, the NiTi alloy was also observed to undergo a detwinning process, dislocation slip and the formation of submicrocrystalline grains, nanocrystallization and amorphous bands.
KW - Fracture
KW - Heat treatment
KW - NiTi shape memory alloy
KW - Plastic deformation
KW - Transmission electron microscopy
UR - http://www.scopus.com/inward/record.url?scp=84962332837&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2016.03.004
DO - 10.1016/j.msea.2016.03.004
M3 - Article
AN - SCOPUS:84962332837
SN - 0921-5093
VL - 662
SP - 564
EP - 577
JO - Materials Science and Engineering: A
JF - Materials Science and Engineering: A
ER -