scholarly journals Texture and Thermal Expansion Anomalies of B19'-Martensite in Tensile Deformed TiNi Shape Memory Alloy

1999 ◽  
Vol 32 (1-4) ◽  
pp. 71-81 ◽  
Author(s):  
V. M. Gundyrev ◽  
V. I. Zel'dovich ◽  
G. A. Sobyanina
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Solution Treated ◽  
Texture Axis ◽  
Ni Alloy ◽  
Axis Parallel ◽  
Dilatometric Studies ◽  
Strain Direction

The dilatometric studies of Ti-50.5 at.% Ni alloy have shown that the thermal expansion coefficient (TEC) of B19'-martensite varies considerably for the solution-treated and tensile-strained samples. In the undeformed state the TEC has the positive value α=9.7.10-6 K-1. After tensile straining the TEC decreases sharply and takes on a negative value (down to – 10.8.10-6 K-1). The reasons for the variation of the TEC of the B19'-phase of the solution-treated and deformed samples are discussed. The tensile straining was found to create in the samples an extremely sharp texture of the phase transformation, with the texture axis parallel to the strain direction. The TEC of monoclinic B1939;-lattice is different in various crystallographic directions and assumes a negative value in the [0 01]B19' direction.

Phase Transformation in Ti-Ni-Ta Shape Memory Alloy

2007 ◽  
Vol 130 ◽  
pp. 147-150 ◽  
Author(s):  
Zdzisław Lekston ◽  
Tomasz Goryczka
Keyword(s):  
Phase Transformation ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Medical Application ◽  
Precipitation Process ◽  
X Ray Diffraction ◽  
Martensitic Transformation Temperature ◽  
X Ray ◽  
Solution Treated

A new Ti50Ni48.7Ta1.3 shape memory alloy was designed for medical application. In order to influence the martensitic transformation temperature the alloy was solution treated and additionally aged at 400oC for various time. Phase transformation was studied applying differential scanning calorimeter (DSC) and X-ray diffraction techniques. The ageing causes that the martensitic transformation occurs in two steps: B2↔R↔B19’ during cooling and heating. During cooling the transformations: B2→R and R→B19’ are well separated whereas on heating they are overlapped. Also ageing causes a shift of temperatures of the martensitic transformation into the higher region. It is due to the precipitation process. Precipitates of the Ni4Ti3 phase were observed. Applied thermal treatment leads to shift of the transformation temperatures below temperature of a human body. This makes the Ti-Ni-Ta alloy attractive for application in medicine.

Shape Memory Behavior of Ti-50.9at%Ni Alloy after ECAE Processes

2007 ◽  
Vol 561-565 ◽  
pp. 2313-2316 ◽  
Author(s):  
Zhi Guo Fan ◽  
Chao Ying Xie
Keyword(s):  
Phase Transformation ◽  
Shape Memory ◽  
Initial Solution ◽  
Transformation Behavior ◽  
Shape Memory Behavior ◽  
Solution Treated ◽  
Ni Alloy ◽  
Coarse Grains ◽  
Shape Memory Properties ◽  
Before And After

The initial coarse grains of Ti-50.9at%Ni were obviously refined after eight ECAE processes. Effects of pressing number on the transformation behavior have been investigated in detail. Comparing with the initial solution-treated Ti-50.9at%Ni, the R-phase transformation was stimulated and the martensitic temperature Ms decreased with ECAE processes at 773K. The shape memory properties of Ti-50.9at%Ni alloy before and after ECAE processes at 773K have been measured. Good one way shape memory and superelasticity were obtained for the submicron-grained Ti-50.9at%Ni alloy.

Microstructure Observation of Ni50Ti45Ta5 Shape Memory Alloy

2011 ◽  
Vol 391-392 ◽  
pp. 452-456
Author(s):  
Chang Wei Gong ◽  
Fen Fang Guo ◽  
Yu Ming Tian ◽  
Yue Sheng Chai
Keyword(s):  
Solid Solution ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Niti Alloy ◽  
Second Phase ◽  
Type Ii ◽  
Microstructure Observation ◽  
Solution Treated ◽  
Second Phase Particles

The phase transformation and microstructure in solution-treated Ni50Ti45Ta5shape memory alloy have been investigated. Two different second-phase particles, (Ti,Ta)2Ni and a tantalum-rich solid solution (β-Ta) mostly located at grain boundaries are observed. The results indicate that the Ta atoms are suggested to replace Ti atoms, instead of Ni atoms in these alloys. Ni50Ti45Ta5 alloy is similar to equiatomic NiTi alloy with near equal transformation temperatures and having one stage transformation. The main lattice twin is type II twin. compound twin also observed because of 5at% Ta addition.

A Novel Training-Free Processed Fe-Mn-Si-Cr-Ni Shape Memory Alloy Undergoing δ → γ Phase Transformation

2016 ◽  
Vol 47 (7) ◽  
pp. 3277-3283 ◽  
Author(s):  
Huabei Peng ◽  
Gaixia Wang ◽  
Yangyang Du ◽  
Shanling Wang ◽  
Jie Chen ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory
Sign in / Sign up

Export Citation Format

Share Document