Thermal Cycling Induced Instability of Martensitic Transformation and the Micro-Mechanism in Solution-Treated Ni51Ti49 Alloy

2018 ◽  
pp. 89-94
Author(s):  
Cai-You Zeng ◽  
Zhong-Xun Zhao ◽  
Yuan-Yuan Li ◽  
Shanshan Cao ◽  
Xiao Ma ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Thermal Cycling ◽  
Solution Treated

scholarly journals Evaluation of the Aging Effect on the Microstructure of Co-28Cr-6Mo-0.3C Alloy: Experimental Characterization and Computational Thermodynamics

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 581 ◽  
Author(s):  
Shahab Zangeneh ◽  
Ersoy Erisir ◽  
Mahmoud Abbasi ◽  
Ali Ramazani
Keyword(s):  
Martensitic Transformation ◽  
Solution Treatment ◽  
Aging Effect ◽  
Sample Solution ◽  
Solution Temperature ◽  
Solution Treated ◽  
The Matrix ◽  
Fcc Phase ◽  
Experimental Findings ◽  
Lamellar Type

In the current research, we studied the role of the solution treatment and aging on the microstructure of a Co–28Cr–5Mo–0.3C alloy. We used metallographic observations, scanning electron microscopy (SEM), and hardness measurements for the evaluations. We also made a comparison between the phase equilibrium calculated with Thermo-Calc, using TCFE8 and TCNI8 thermodynamic databases and experimental findings. The experimental results showed that the transformation of the metastable FCC phase to the HCP phase during aging was extremely sensitive to the solution treatment prior to aging. The effect of the increase in the solution temperature and time was detectable through promotion of the martensitic transformation during quenching in which HCP1 (straight bands) and HCP2 (lamellar-type constitution) phases had developed. In contrast, a low solution temperature and time caused most of the primary carbides to remain in an undissolved condition in the matrix; therefore, during aging, no sign of the FCC to HCP1 (straight bands) phase transformation could be observed. However, we observed the formation of the HCP2 phase (lamellar-type constitution) at the grain boundaries. In addition, the X-ray diffraction pattern indicated that the sample solution treated at lower temperatures and shorter times had a stronger martensitic transformation during aging compared to the sample solution treated at higher temperatures and longer times. Hardness measurements confirmed the results. Thermodynamical calculations showed that an agreement existed between the experiments and calculations. We also discuss the results from the TCFE8 and TCNI8 databases.

Effect of Thermal Cycling (γε) on Martensitic Transformation Kinetics and Damping Capacity of Fe –17mass%Mn Alloy

2006 ◽  
Vol 319 ◽  
pp. 59-66 ◽  
Author(s):  
Young Kook Lee ◽  
Young Seob Seo ◽  
Won Jin ◽  
Chong Sool Choi
Keyword(s):  
Martensitic Transformation ◽  
Thermal Cycling ◽  
Damping Capacity ◽  
Transformation Kinetics ◽  
Burst Mode ◽  
Martensite Content ◽  
Nucleation Sites ◽  
Ε Martensite

Effect of thermal cycling(γ↔ε) on γ→ε martensitic transformation kinetics and damping capacity of Fe-17mass%Mn alloy has been studied. The amount of ε martensite increases with thermal cycling in spite of decrease in Ms temperature. The increase in ε martensite content with thermal cycling is attributable to an increase in the density of martensite nucleation sites by introduction of dislocations during thermal cycling. The γ→ε martensitic transformation kinetics shows a burst mode in the non-cycled specimen, while the kinetics exhibits a sigmoidal mode in the cycled specimens. The damping capacity of the alloy increases with increasing the ε martensite content in the non-cycled specimen. On the contrary, the damping capacity of the alloy decreases with increasing the ε martensite content in the cycled specimens. The reason is that the dislocations introduced during thermal cycling, which obstruct the movement of the damping sources, become more with thermal cycling.

Variation in kinetics of martensitic transformation during partial thermal cycling of the TiNi alloy

2014 ◽  
Vol 582 ◽  
pp. 46-52 ◽  
Author(s):  
Sergey Belyaev ◽  
Natalia Resnina ◽  
Alexey Sibirev ◽  
Ivan Lomakin
Keyword(s):  
Martensitic Transformation ◽  
Thermal Cycling ◽  
Tini Alloy ◽  
Kinetics Of

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.

Martensitic Transformation Behavior and Shape Memory Effect of an Aged Ni-rich Ti-Ni-Hf High Temperature Shape Memory Alloy

2008 ◽  
Vol 138 ◽  
pp. 399-406 ◽  
Author(s):  
Xiang Long Meng ◽  
Yu Dong Fu ◽  
Wei Cai ◽  
J.X. Zhang ◽  
Qing Fen Li ◽  
...  
Keyword(s):  
High Temperature ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Aging Temperature ◽  
Transformation Behavior ◽  
Transformation Temperatures ◽  
Solution Treated

The martensitic transformation behavior and shape memory effect (SME) have been investigated in a Ni-rich Ti29.6Ni50.4Hf20 high temperature shape memory alloy (SMA) in the present study. After aging, the transformation temperatures of Ti29.6Ni50.4Hf20 alloy increase obviously due to the precipitation of (Ti,Hf)3Ni4 particles. And the transformation sequence changes from one-step to two-step. When the experimental alloy is aged at different temperatures for 2h, the transformation temperatures increase rapidly with increasing the aging temperature and then change slightly with further increasing the aging temperature. Most of the martensite variants preferentially oriented in the aged Ti29.6Ni50.4Hf20 alloy. The aged Ti29.6Ni50.4Hf20 alloy shows the better thermal stability of transformation temperatures than the solution-treated one because the precipitates depress the introduction of defects during thermal cycling. In addition, the proper aged Ti29.6Ni50.4Hf20 alloy also shows the larger SME than the solution-treated one since the precipitates strengthen the matrix strongly.

Martensitic Transformation and Response Characteristics in Bias-SMA Spring Actuators with Thermal Cycling

2012 ◽  
Vol 488-489 ◽  
pp. 118-123
Author(s):  
K.K. Jee ◽  
W.I. Choi ◽  
K.H. Kim ◽  
W.Y. Jang
Keyword(s):  
Martensitic Transformation ◽  
Heat Flow ◽  
Thermal Cycling ◽  
Temperature Difference ◽  
Aging Temperature ◽  
Transformation Temperature ◽  
Lattice Defects ◽  
Training Effect ◽  
Response Characteristics ◽  
Sma Spring

The effect of thermal cycling on the martensitic transformation and response characteristics has been studied in bias-SMA spring actuators aged at 350 °C ~ 500 °C. As the number of thermal cycling increases, the Ms temperature of the SMA spring showing only B2→B19' martensitic transformation by aging at 350 or 500 °C goes down. However, SMA spring in which B2→R→B19' martensitic transformation taken place by aging at 400 or 450 °C shows multi-step transformations i.e., M1 and M2 transformations with thermal cycling. The heat flow of M2 transformation increases while the transformation temperature difference between M1 and M2 transformations is enlarged as the number of cycling increases. The recovery displacement and force of bias-SMA spring actuator increase up to the 10th cycle and the extent of increase is the largest at aging temperature of 500 °C. However, both recovery properties decrease after the 103 or 104 cycles, while the decreasing tendency becomes larger with a rise in aging temperature. Such a change in recovery characteristics of bias-SMA spring actuator with thermal cycling is discussed in connection with training effect or lattice defects introduced during thermal cycling.

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