Transformation relaxation and aging in a CuZnAl shape-memory alloy studied by modulated differential scanning calorimetry

1998 ◽  
Vol 29 (11) ◽  
pp. 2697-2705 ◽  
Author(s):  
Z. G. Wei
Keyword(s):  
Differential Scanning Calorimetry ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry

Effect of Electroplastic Deformation on Martensitic Transformation in Coarse Grained and Ultrafine Grained Ni-Ti Shape Memory Alloy

2008 ◽  
Vol 584-586 ◽  
pp. 127-132 ◽  
Author(s):  
Anastasia E. Sergeeva ◽  
Daria Setman ◽  
Michael Zehetbauer ◽  
Sergey Prokoshkin ◽  
Vladimir V. Stolyarov
Keyword(s):  
Differential Scanning Calorimetry ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Cold Rolling ◽  
Shape Memory ◽  
Coarse Grained ◽  
Scanning Calorimetry ◽  
Structure Relaxation ◽  
Differential Scanning Calorimetry Method ◽  
Ultrafine Grained

The aim of this paper is the investigation of electroplastic deformation (EPD) and subsequent annealing influence on martensitic transformation in the shape memory Ni50.7Ti49.3 alloy. Using differential scanning calorimetry method it was shown that EPD at the low strain stimulates structure relaxation and recovers martensitic transformation in cooling, which is usually suppressed by cold rolling.

scholarly journals Nanocrystal, phase transformation and microstructure of Ni50Ti50 shape memory alloy

2018 ◽  
Vol 24 (02) ◽  
pp. 22-25
Author(s):  
Dovchinvanchig M ◽  
Chunwang Zhao
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
One Step ◽  
Niti Matrix ◽  
Electronic Microscope

The nanocrystal, phase transformation and microstructure behavior of Ni50Ti50 shape memory alloy was investigated by scanning electronic microscope, X-ray diffraction and differential scanning calorimetry. The results showed that the microstructure of Ni-Ti binary alloy consists of the NiTi2 phase and the NiTi matrix phase. One-step phase transformation was observed alloy.

Thermal Cycling Influence on the Transformation Characteristics of a Ni50Ti48Nb2 Shape Memory Alloy

2017 ◽  
Vol 68 (5) ◽  
pp. 991-996
Author(s):  
Ioana Arina Gherghescu ◽  
Sorin Ciuca ◽  
Gabriela Liliana Jicmon ◽  
Ruxandra Elena Dumitrescu ◽  
Mihai Branzei
Keyword(s):  
Differential Scanning Calorimetry ◽  
Shape Memory Alloy ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Critical Points ◽  
Mechanical Stability ◽  
Alloy Sample ◽  
Scanning Calorimetry ◽  
Metallic Part ◽  
Two Samples

The alloy was chosen in order to obtain a shape memory alloy having a wider hysteresis than equiatomic NiTi, that involves a better thermo-mechanical stability. Two samples investigated by differential scanning calorimetry (DSC) were previously annealed at 800oC/12 h and, respectively, 900 �C/12 h followed by furnace cooling. These were afterwards submitted to thermal cycling. The thermal cycling of a Ni50Ti48Nb2 alloy sample previously annealed at 900 �C/12 h results in lower critical points and higher hysteresis values as compared to those of the sample annealed at 800�C/12h, also submitted to thermal cycling. Thus, annealing a metallic part made of such an alloy at 900� C/12 h followed by thermal cycling prior to putting it into service enhances its reliability.

Effect of the Cooling Time in Annealing at 350°C on the Phase Transformation Temperatures of a Ni55Ti45 wt. Alloy

2015 ◽  
Vol 1120-1121 ◽  
pp. 958-961
Author(s):  
Tadeu Castro da Silva ◽  
Daniel Monteiro Rosa ◽  
Edson Paulo da Silva
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Cooling Time ◽  
Phase Transformation Temperature ◽  
Thermal Treatments ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Transformation Temperatures

When submitted to annealing thermal treatments Shape Memory Alloys have their phase transformation temperatures effected. The aim of the present work is to investigate the effects of cooling time in the phase transformation temperatures of Ni55Ti45in w.t. % alloy annealed at 350°C. Samples of this alloy were maintained at 350°C for one hour and then cooled in the same furnace for 10 minutes, 1 hour and 24 hours. The phase transformation temperatures were measured by means of Differential Scanning Calorimetry (DSC) at cooling and heating rates of 20°C/min. The results show that the annealing at 350°C changed the phase transformation up to 54%. For 10 minutes cooling time the Mftemperature increase from 15,65°C to 24,1°C. For the others cooling times the phase transformation temperature did not change significantly. Therefore, the cooling time for the annealing at 350°C did not effect the phase transformation temperatures of the Ni45Ti55in wt % shape memory alloy.

The Influence of Hafnium Content, Cold Work, and Heat Treatment on the R-Phase Transformation of Niti Based Shape Memory Alloys

1996 ◽  
Vol 459 ◽  
Author(s):  
Chen Zhang ◽  
Paul E. Thoma ◽  
Ralph H. Zee
Keyword(s):  
Heat Treatment ◽  
Differential Scanning Calorimetry ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Cold Work ◽  
Niti Shape Memory Alloy ◽  
Scanning Calorimetry ◽  
Complex Manner

ABSTRACTThe R-phase transformation of a Ti-rich NiTi shape memory alloy (SMA) and two ternary SMAs having the compositions Ni49Ti51-XHfx with lat% and 3at% Hf, has been investigated. The influence of cold work (CW) and heat treatment (HT) on the R-phase transformation is analyzed thermally using Differential Scanning Calorimetry (DSC). Results show that the R-phase transformation depends on the SMA composition as well as the CW and HT conditions in a complex manner. For example, the formation of R-phase upon cooling from austenite (A) is increasingly suppressed with the substitution of Hf for Ti. For the ternary SMA with 3at% Hf, the A→R and R→A transformations are observed only at relatively large amounts of CW (above approximately 40%) and at a high HT temperature (450°C). DSC results also show that for the Ti-rich NiTi and the ternary SMA containing lat% Hf, the A→R and R→A transformation temperatures (TTs) are insensitive to cold work at a HT temperature of 450°C. However, at a lower HT temperature of 350°C, the TTs are found to decrease with increasing CW. For a given CW, the A→R and R→A transformations decrease with decreasing HT temperature and the effect is greatest at high CW (>50%) conditions. An effort is made to identify the factors responsible for the observed behavior in the R-phase transformation.

Modeling of Electrical Resistivity Evolution Using Free Energy Analysis for NiTi Shape Memory Alloy Wires

2011 ◽  
Vol 311-313 ◽  
pp. 2282-2285
Author(s):  
Jian Jun Zhang
Keyword(s):  
Electrical Resistivity ◽  
Free Energy ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Free Energy Change ◽  
Energy Change ◽  
Niti Shape Memory Alloy ◽  
Scanning Calorimetry ◽  
Proposed Model ◽  
Free Energy Analysis

This paper presents a transformation kinetics model of NiTi shape memory alloy (SMA) wires based on electrical resistivity (ER) derivative study under the assumption that the derivative of electrical resistivity with respect to temperature is in linear relationship with the derivative of free energy change with respect to temperature. Free energy change and electrical resistivity properties of SMA are analyzed based on differential scanning calorimetry (DSC) experiments during phase transformation. The simulated evolution of electrical resistivity during thermomechanical transformation is presented using the proposed model.

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