کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1613835 | 1005601 | 2013 | 5 صفحه PDF | دانلود رایگان |
The processes of structure formation in Ti–Ni and Ti–Nb–Zr, Ti–Nb–Ta shape memory alloys under thermomechanical treatment were studied. The thermomechanical treatment comprised cold rolling with true strains from e = 0.25 to 2 and post-deformation annealing in the 300–900 °C temperature range. The differences in these processes between the two groups of alloys were evaluated in terms of their effect on nanostructures formation. The main conclusions are as follows: nanostructures created by thermomechanical treatment are quite useful, as they show a radical improvement of shape memory alloy functional properties. A specific nanostructure (nanocrystalline structure, nanosubgrained structure or their mixture) should be privileged considering other structural and technological factors such as mechanical damage, formation of a brittle second phase, etc., as well as application requirements.
► Severe cold rolling of Ti–Ni SMA creates a mixed amorphous-nanocrystalline structure, whereas severe cold rolling of Ti–Nb-(Zr,Ta) SMA does not imply material amorphization.
► Annealing of the severely deformed Ti–Ni alloy leads to a nanocrystalline structure formed by nanosize grains of two different origins: issued from recrystallization of the amorphous material and resulted from deformation-induced grain refinement.
► Annealing of the moderately deformed Ti–Nb-(Zr,Ta) alloys leads to the nanosubgrain structure in the material. Both nanocrystalline and nanosubgrain structures are actually effective for radical improvement of Ti–Ni and Ti–Nb-(Zr,Ta) SMA functional properties.
Journal: Journal of Alloys and Compounds - Volume 577, Supplement 1, 15 November 2013, Pages S418–S422