scholarly journals Martensitic transformation in Ti-Ni-Cu shape memory wires broken by thermal cycling under constant load

2001 ◽  
Vol 11 (PR8) ◽  
pp. Pr8-375-Pr8-380 ◽  
Author(s):  
C.J. de Araújo ◽  
M. Morin ◽  
G. Guénin
Keyword(s):  
Martensitic Transformation ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Constant Load

Shape Memory Effect and Superelasticity of an Equiatomic Ti-Ni Alloy with Surface Sulfide Layers

2006 ◽  
Vol 510-511 ◽  
pp. 262-265
Author(s):  
Tae Hyun Nam ◽  
Shin Goo Hur ◽  
Jae Hwa Lee ◽  
Gyu Bong Cho
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Tensile Tests ◽  
Constant Load ◽  
Ni Alloy ◽  
Memory Characteristics ◽  
Scanning Electron ◽  
Start Temperature

Shape memory characteristics and superelasticity of an equiatomic Ti-Ni alloy with surface sulfide layers were investigated by means of thermal cycling tests under constant load, tensile tests, and scanning electron microscopy. Martensitic transformation start temperature (Ms) increased by sulfidation, which is ascribed to a compressive stress imposed by surface sulfide layers. Surface sulfide layers were found to make transformation elongation be small when their thickness was less than 5 ㎛. This is ascribed to the fact that the surface sulfide layers were not detached from substrates and constrained martensitic transformation. When thickness of the surface sulfide layers was 35 ㎛, transformation elongation was not affected by them because they were detached during transformation. Superelastic recovery decreased by the sulfide layers when their thickness was about 5 ㎛, while it did not change when the thickness was about 35 ㎛.

The effect of thermal cycling on the martensitic transformation in equiatomic CuZr shape memory alloy

2015 ◽  
Vol 653 ◽  
pp. 591-595 ◽  
Author(s):  
C.A. Biffi ◽  
M. Coduri ◽  
H. Yoshida ◽  
Y. Soejima ◽  
M. Nishida ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Thermal Cycling ◽  
Shape Memory

scholarly journals Effect of Stoichiometry on Shape Memory Properties and Functional Stability of Ti–Ni–Pd Alloys

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 798 ◽  
Author(s):  
Yuki Hattori ◽  
Takahiro Taguchi ◽  
Hee Kim ◽  
Shuichi Miyazaki
Keyword(s):  
High Temperature ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Stoichiometric Composition ◽  
Atomic Ratio ◽  
Transformation Temperatures ◽  
Shape Memory Properties ◽  
Ti Content

Ti–Ni–Pd shape memory alloys are promising candidates for high-temperature actuators operating at above 373 K. One of the key issues in developing high-temperature shape memory alloys is the degradation of shape memory properties and dimensional stabilities because plastic deformation becomes more pronounced at higher working temperature ranges. In this study, the effect of the Ti:(Ni + Pd) atomic ratio in TixNi70−xPd30 alloys with Ti content in the range from 49 at.% to 52 at.% on the martensitic transformation temperatures, microstructures and shape memory properties during thermal cycling under constant stresses were investigated. The martensitic transformation temperatures decreased with increasing or decreasing Ti content from the stoichiometric composition. In both Ti-rich and Ti-lean alloys, the transformation temperatures decreased during thermal cycling and the degree of decrease in the transformation temperatures became more pronounced as the composition of the alloy departed from the stoichiometric composition. Ti2Pd and P phases were formed during thermal cycling in Ti-rich and Ti-lean alloys, respectively. Both Ti-rich and Ti-lean alloys exhibited superior dimensional stabilities and excellent shape memory properties with higher recovery ratio and larger work output during thermal cycling under constant stresses when compared with the alloys with near-stoichiometric composition.

scholarly journals Martensitic Transformation and Its Thermal Cycling Stability in Ni56Mn21Cu4Ga19 High-Temperature Shape Memory Ribbon

2014 ◽  
Vol 28 (2) ◽  
pp. 243-248 ◽  
Author(s):  
Xi-Li Lu ◽  
De-Xi Su ◽  
Feng Chen ◽  
Wei-Li Liu ◽  
Yang-Guang Shi ◽  
...  
Keyword(s):  
High Temperature ◽  
Martensitic Transformation ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Cycling Stability

Unusual Multistage Martensitic Transformation in TiNi Shape Memory Alloy after Thermal Cycling

2013 ◽  
Vol 738-739 ◽  
pp. 372-376 ◽  
Author(s):  
Aleksey Sibirev ◽  
Sergey Belyaev ◽  
Natalia Resnina
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Temperature Interval ◽  
Defect Structure ◽  
Tini Alloy ◽  
Thermal Cycles ◽  
Unusual Phenomenon ◽  
Kinetics Of

Variation in kinetics of martensitic transformation, in an equiatomic TiNi shape memory alloy, during thermal cycles was investigated. Samples annealed at 500 °C for 1 hour were subjected to repeated thermal cycles, through the temperature range of martensitic transformation. Unusual 4-stage martensitic transformation during cooling after 30 thermal cycles was observed. Moreover, a new unusual phenomenon was found in the preliminary thermal cycled TiNi alloy. It was observed that variation in the highest temperature Th of thermal cycles temperature interval resulted in the redistribution of released heat among four calorimetric peaks, observed on cooling. It was found that if the Th temperature did not exceed 240 °C the variation in kinetics was repeatable, and determined only by the value of Th. It was assumed that the defect structure induced on preliminary thermal cycling changes reversibly on cooling and heating.

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