Phenomenological analysis of martensitic transformation in cold-rolled TiNi-base shape memory alloys
Journal
Materials Chemistry and Physics
Journal Volume
68
Journal Issue
1-3
Pages
149-156
Date Issued
2001
Author(s)
Abstract
The martensitic transformation in cold-rolled TiNi-base shape memory alloys has shown that the first reverse martensitic transformation temperature (A1*) increases with an increasing amount of cold rolling due to the increment of the transformation energy barrier introduced by cold-rolling induced dislocations. Meanwhile, the increment of A1* temperature increases linearly with an increase in the specimen's solution-treated hardness. A phenomenological analysis from the thermodynamic viewpoint of cold-rolling induced dislocations can elucidate these features successfully. After the first reverse transformation, the strengthening effects of retained dislocations on martensitic transformation temperatures follow the equation M* = TO - K Δσys. The K value is found to be proportional to the specimen's solution-treated hardness, because the harder specimen has the stronger interaction of martensite plates and dislocations induced by cold rolling. The thermal hysteresis of A2* - M*, associated with the frictional work during the transformation, does not obviously change in the cold-rolled TiNi-base shape memory alloys.
SDGs
Publisher
Elsevier Sequoia SA, Lausanne
Type
journal article