scholarly journals Microstructural and Mechanical Stability of a Ti-50.8 at.% Ni Shape Memory Alloy Achieved by Thermal Cycling with a Large Number of Cycles

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 227 ◽  
Author(s):  
Churakova ◽  
Gunderov
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloy ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Temperature Change ◽  
Mechanical Stability ◽  
Martensitic Transformations ◽  
Coarse Grained ◽  
Ultrafine Grained ◽  
Number Of Cycles

The influence of thermal cycling (TC) with a large number of cycles on the microstructure, the parameters of martensitic transformations (MTs), and the mechanical properties of a Ti-50.8 at.% Ni shape-memory alloy in coarse-grained (CG) and ultrafine-grained (UFG) states was investigated. The effect of microstructural and mechanical stability was found in both coarse-grained and ultrafine-grained states starting from the 100th cycle of martensitic transformations. In addition, an unusual temperature change was observed in martensitic transformations occurring with the formation of an intermediate R phase.

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 Mechanical behavior and fractographic analysis of a TiNi alloy with various thermomechanical treatment

2019 ◽  
Vol 298 ◽  
pp. 00019 ◽  
Author(s):  
Anna Churakova ◽  
Anna Yudahina ◽  
Elina Kayumova ◽  
Nikita Tolstov
Keyword(s):  
Dislocation Density ◽  
Thermal Cycling ◽  
Thermomechanical Treatment ◽  
Martensitic Transformations ◽  
Coarse Grained ◽  
Tini Alloy ◽  
Phase Hardening ◽  
Cold Upsetting ◽  
Cycling Treatment ◽  
Ultrafine Grained

Influence of thermomechanical treatment (deformation, thermal cycling treatment in the temperature range of martensitic transformations B2-B19’) on the TiNi alloys’ mechanical behaviour and fracture was studied. Different states were considered, they are initial coarse-grained (CG), ultrafine-grained (UFG) after ECAP (with a grain size of 200 nm), the state after ECAP and cold upsetting by 30% - UFG state with high dislocation density. It was shown that thermal cycling causes some increase in dislocation density, strength and microhardness in all the states. Thermal cycling of UFG alloys allows forming the states with non-equilibrium grain boundaries, with additional dislocations of “phase hardening”. The nature of the fracture was analysed in the TiNi alloy in various states.

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.

Microstructure Evolution and Mechanical Behavior in Shape Memory Nanostructured TiNi Alloy

2018 ◽  
Vol 385 ◽  
pp. 169-174 ◽  
Author(s):  
Anna Misochenko ◽  
Jeevanandham Vijaya Tilak Kumar ◽  
Sudha Jayaprakasam ◽  
K. Anantha Padmanabhan ◽  
Vladimir Stolyarov
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Microstructure Evolution ◽  
Mechanical Response ◽  
Coarse Grained ◽  
Tini Alloy ◽  
Nanostructured Alloys

Influence of grain size on the martensitic transformation and mechanical properties of shape memory alloy Тi49.3Ni50.7 was studied. The features of the mechanical response of coarse-grained and nanostructured alloys were identified. The microstructure investigations involved the use of TEM and SEM.

Martensitic transformations and kinetics in Ti-Ni-Cu-Hf shape memory alloy

2021 ◽  
pp. 129732
Author(s):  
Jun Li ◽  
Kuishan Sun ◽  
Yuqi Jiang ◽  
Xianglong Meng ◽  
Wei Cai
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Martensitic Transformations

Transformation hysteresis and shape memory effect of an ultrafine-grained TiNiNb shape memory alloy

2014 ◽  
Vol 54 ◽  
pp. 133-135 ◽  
Author(s):  
P.C. Jiang ◽  
Y.F. Zheng ◽  
Y.X. Tong ◽  
F. Chen ◽  
B. Tian ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Ultrafine Grained ◽  
Transformation Hysteresis

scholarly journals Experimental and Numerical Analysis of the Mechanical Properties of a Pretreated Shape Memory Alloy Wire in a Self-Centering Steel Brace

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 80
Author(s):  
Bo Zhang ◽  
Sizhi Zeng ◽  
Fenghua Tang ◽  
Shujun Hu ◽  
Qiang Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Loading Rate ◽  
Effective Elastic Modulus ◽  
Maximum Energy ◽  
Numerical Results ◽  
Energy Dissipation Capacity

As a stimulus-sensitive material, the difference in composition, fabrication process, and influencing factors will have a great effect on the mechanical properties of a superelastic Ni-Ti shape memory alloy (SMA) wire, so the seismic performance of the self-centering steel brace with SMA wires may not be accurately obtained. In this paper, the cyclic tensile tests of a kind of SMA wire with a 1 mm diameter and special element composition were tested under multi-working conditions, which were pretreated by first tensioning to the 0.06 strain amplitude for 40 cycles, so the mechanical properties of the pretreated SMA wires can be simulated in detail. The accuracy of the numerical results with the improved model of Graesser’s theory was verified by a comparison to the experimental results. The experimental results show that the number of cycles has no significant effect on the mechanical properties of SMA wires after a certain number of cyclic tensile training. With the loading rate increasing, the pinch effect of the hysteresis curves will be enlarged, while the effective elastic modulus and slope of the transformation stresses in the process of loading and unloading are also increased, and the maximum energy dissipation capacity of the SMA wires appears at a loading rate of 0.675 mm/s. Moreover, with the initial strain increasing, the slope of the transformation stresses in the process of loading is increased, while the effective elastic modulus and slope of the transformation stresses in the process of unloading are decreased, and the maximum energy dissipation capacity appears at the initial strain of 0.0075. In addition, a good agreement between the test and numerical results is obtained by comparing with the hysteresis curves and energy dissipation values, so the numerical model is useful to predict the stress–strain relations at different stages. The test and numerical results will also provide a basis for the design of corresponding self-centering steel dampers.

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