scholarly journals Internal Friction and Dynamic Modulus in Ultra-High Temperature Ru-Nb Functional Intermetallics / Tarcie Wewnętrzne I Moduł Dynamiczny W Bardzo Wysoko Temperaturowych Funkcjonalnych Związkach Międzymetalicznych Z Układu Ru-Nb

2015 ◽  
Vol 60 (4) ◽  
pp. 3069-3072
Author(s):  
M.L. Nó ◽  
L. Dirand ◽  
A. Denquin ◽  
J. San Juan
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Martensitic Transformations ◽  
Time Dependent ◽  
Structural Defects ◽  
Complete Analysis ◽  
Internal Friction Peak ◽  
Thermally Activated ◽  
Temperature Ranges ◽  
Lower Temperature

In the present work we have studied the high-temperature shape memory alloys based on the Ru-Nb system by using two mechanical spectrometers working in temperature ranges from 200 to 1450ºC and -150 to 900ºC. We have studied internal friction peaks linked to the martensitic transformations in the range from 300 to 1200ºC. In addition, we have evidenced another internal friction peak at lower temperature than the transformations peaks, which apparently exhibits the behaviour of a thermally activated relaxation peak, but in fact is a strongly time-dependent peak. We have carefully studied this peak and discussed its microscopic origin, concluding that it is related to the interaction of some structural defects with martensite interfaces. Finally, we perform a complete analysis of the whole internal friction spectrum, taking into account the possible relationship between the time-dependent peak and the martensitic transformation behaviour.

A Study on Influence of Annealing and Aging on High Temperature Internal Friction in Al-Zr Alloy

2012 ◽  
Vol 535-537 ◽  
pp. 1027-1030
Author(s):  
Xiao Hui Cao ◽  
Yu Wang
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Grain Boundary ◽  
Low Frequency ◽  
Grain Boundary Sliding ◽  
High Temperature Side ◽  
Internal Friction Peak ◽  
Average Grain Size ◽  
Lower Temperature ◽  
Zr Alloy

By using a low frequency inverted torsion pendulum, the high temperature internal friction spectra of Al-0.02wt%Zr and Al-0.1wt%Zr alloys were investigated respectively. In Al-0.02wt%Zr alloy, the conventional grain boundary internal friction peak (Pg) is observed with some small unstable peaks. In Al-0.1wt%Zr alloy, the bamboo peak is observed to appear at the high temperature side of the conventional grain boundary internal friction peak. The conventional grain boundary internal friction peak decreased and moved to higher temperature. The bamboo peak owns an activation energy of 1.75eV. When average grain size exceeded the diameter of samples, Pb strength was reduced and its position was shifted to a lower temperature. Based on the grain boundary sliding model, Pg and Pb peaks were explained. Their dependence on annealing temperature and time was determined by considering the effects of contained Ce atoms and other impurities on the relaxation across grain boundary.

Internal Friction and Dynamic Modulus in High Temperature Ru-Nb Shape Memory Intermetallics

2012 ◽  
Vol 1516 ◽  
pp. 235-240
Author(s):  
Laura Dirand ◽  
Maria L. Nó ◽  
Karine Chastaing ◽  
Anne Denquin ◽  
Jose San Juan
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Shape Memory ◽  
Dynamic Modulus ◽  
Martensitic Transformations ◽  
Theoretical Models ◽  
Structural Defects ◽  
Sensors And Actuators ◽  
Very High ◽  
Internal Friction Spectra

ABSTRACTNowadays, aeronautic and aerospace are the more demanding sectors for shape memory alloys (SMA) after the bio-medical one. In particular the interest has been recently focused on very high temperature SMA, which would be able of working as sensors and actuators in the hot areas of the engines and exaust devices.In the present work we undertook a study of the Ru-Nb SMA Intermetallics, which undergo two succesive martensitic transformations around 1050 K and 1180 K respectively, depending on composition. This study has been focused on measurements of internal friction spectra and dynamic modulus variation up to 1700 K, which have been carried out in a sub-resonant torsion mechanical spectrometer.The internal friction and dynamic modulus have been studied as a function of the heating-cooling rate and the frequency in order to compare experimental behaviour with theoretical models for martensitic transformations. In addition to the internal friction peaks linked to both martensitic transformations we have also observed a complex relaxation process around 950 K, which seems to be linked to the interaction of the martensite interfaces with structural defects. An analysis and discusion of the potential microscopic mechanisms are also presented.

Reaction Mechanisms of Li5La3Ta2O12 Powder with Ambient Air: H+/Li+ Exchange with Water

2012 ◽  
Vol 463-464 ◽  
pp. 123-127 ◽  
Author(s):  
Wei Guo Wang ◽  
Qian Feng Fang ◽  
Gang Ling Hao
Keyword(s):  
Internal Friction ◽  
Lithium Ion ◽  
Ambient Air ◽  
Exchange Property ◽  
Measured Temperature ◽  
Internal Friction Peak ◽  
Lower Temperature ◽  
Lithium Ion Conductors ◽  
Grain Surface ◽  
Water Gas

The proton/lithium exchange property of the garnet-related lithium-ion conductors Li5La3Ta2O12 is shown to occur at room temperature under ambient air. The internal friction, TGA analysis, and IR spectroscopy techniques are used to investigate the reaction mechanism. XRPD analysis demonstrates the topotactic character of the exchange reaction. The water gas in ambient air is adsorbed on the grain surface and then to exchange proton for lithium ion into the garnet structure,(Li5-xHx)La3Ta2O12. The H+/Li+ exchanging processes are reversible. When the measured temperature is higher over 573K, the internal friction peak gradually shifts toward lower temperature and the like garnet-like phase is recovered.

Microstructure and Damping Capacity of AlNp/Mg-Al Composites with Different Particle Contents

2017 ◽  
Vol 898 ◽  
pp. 933-943 ◽  
Author(s):  
Yong Wang ◽  
Kai Ming Cheng ◽  
Ji Xue Zhou ◽  
Yuan Sheng Yang
Keyword(s):  
Internal Friction ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Damping Capacity ◽  
Matrix Composites ◽  
Internal Friction Peak ◽  
Experimental Frequency ◽  
The Matrix ◽  
Temperature Ranges ◽  
Interface Sliding

The AlN particles reinforced magnesium-aluminum matrix composites were fabricated by powder metallurgy and the damping mechanism was discussed. The results showed that the best damping capacity of composite reached with the addition of 6wt% AlN reinforcement, while the AlN particles were uniformly dispersed in the matrix. The damping capacity of composites decreases with the increasing of the reinforcement content and the experimental frequency. The internal friction peak related to dislocation appearance in the temperature ranges of 100-150°C. In addition, another internal friction peak of composites between 200 and 250°C arose, which was related to interface sliding.

scholarly journals Internal Friction during Martensitic Transformations in Ultra-high Temperature Ru-Nb Shape Memory Alloys

2015 ◽  
Vol 2 ◽  
pp. S809-S812 ◽  
Author(s):  
M.L. Nó ◽  
L. Dirand ◽  
A. Denquin ◽  
L. Usategui ◽  
G.A. López ◽  
...  
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Martensitic Transformations ◽  
Ultra High Temperature

scholarly journals High-Temperature Dielectric Relaxation Behaviors in Mn3O4 Polycrystals

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4026 ◽  
Author(s):  
Songwei Wang ◽  
Xin Zhang ◽  
Rong Yao ◽  
Liguo Fan ◽  
Huaiying Zhou
Keyword(s):  
High Temperature ◽  
Dielectric Relaxation ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Thermally Activated ◽  
Dielectric Relaxations ◽  
Plasma Sintering ◽  
Ptcr Effect ◽  
Temperature Relaxation ◽  
Lower Temperature

High temperature dielectric relaxation behaviors of single phase Mn3O4 polycrystalline ceramics prepared by spark plasma sintering technology have been studied. Two dielectric relaxations were observed in the temperature range of 200 K–330 K and in the frequency range of 20 Hz–10 MHz. The lower temperature relaxation is a type of thermally activated relaxation process, which mainly results from the hopping of oxygen vacancies based on the activation energy analysis. There is another abnormal dielectric phenomenon that is different from the conventional thermally activated behavior and is related to a positive temperature coefficient of resistance (PTCR) effect in the temperature region. In line with the impedance analyses, we distinguished the contributions of grains and grain boundaries. A comparison of the frequency-dependent spectra of the imaginary impedance with imaginary electric modulus suggests that both the long range conduction and the localized conduction are responsible for the dielectric relaxations in the Mn3O4 polycrystalline samples.

Hydrogen-Induced Mechanical Losses in Oxygen-Free Copper

2012 ◽  
Vol 184 ◽  
pp. 122-127 ◽  
Author(s):  
Mykola Ivanchenko ◽  
Yuriy Yagodzinskyy ◽  
H. Hänninen
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Oxygen Content ◽  
Hydrogen Atoms ◽  
Internal Friction Peak ◽  
Exponential Factor ◽  
Hydrogen Charging ◽  
High Temperature Component ◽  
Temperature Component ◽  
High Temperature Components

Two oxygen-free copper grades with purity of 99.99 % were studied by means of free decay inverted torsion pendulum at the temperature range of 90 – 300 K and frequencies of 0.5 – 2 Hz. One copper grade was oxygen free electrolytically refined copper with oxygen content of 1.2 wt. ppm. The other one was oxygen-free phosphorous-alloyed grade with oxygen content less than 5 wt. ppm and phosphorous content of 30 – 70 wt. ppm. Electrochemical hydrogen charging induces a complex internal friction peak in the studied copper grades. The observed internal friction peak has a relaxation origin with apparent activation enthalpy and pre-exponential factor for the oxygen-free grade of 0.276 ± 0.002 eV and 10-11.59 ± 0.08 s, respectively. The internal friction peak can be fitted by three broadened Debye peaks (P1, P2 and P3) with activation enthalpies and pre-exponential factors of 0.248 ± 0.003 eV and 10-11.4 ± 0.4 s; 0.297 ± 0.004 eV and 10-11.8 ± 0.2 s; 0.36 ± 0.04 eV and 10-12.7 ± 1.4 s, respectively. Phosphorous doping markedly reduces the height of the observed peak. It was also shown that prior deformation by tension suppresses high-temperature components of the complex internal friction peak. Mechanism of relaxation is presumably caused by interaction of H – H pairs (low-temperature component, peak P1), interaction of hydrogen atoms with dislocations (P2) and interaction of hydrogen with impurities (high-temperature component, peak P3). Absorption of hydrogen in the studied copper grades during electrochemical hydrogen charging was confirmed by the thermal desorption method.

Ferroelectric Properties and Internal Friction in Doped PZT Ceramics

2015 ◽  
Vol 644 ◽  
pp. 171-174
Author(s):  
Dariusz Bochenek ◽  
Przemysław Niemiec ◽  
Radosław Zachariasz ◽  
Ryszard Skulski
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Ferroelectric Properties ◽  
Low Frequency ◽  
Electric Permittivity ◽  
Pressing Method ◽  
Pzt Ceramics ◽  
Low Dielectric ◽  
Temperature Ranges ◽  
Similar Temperature

Multicomponent PZT-type solid solution with composition: Pb0.975Ba0.01Ca0.01Sr0.005 (Zr0.52Ti0.48)O3+1.4wt.%Bi2O3+0.3wt.%GeO obtained by hot uniaxial pressing method is described in this paper. There are presented the results of studies of structural, dielectric and internal friction of obtained multicomponent PZT-type ceramics. It has been stated that the dielectric anomalies and internal friction anomalies are observed in similar temperature ranges. Obtained PZT-type ceramics have high value of the dielectric permittivity and low dielectric losses. The high temperature of phase transition and high value of electric permittivity allow considering this material as a base for low frequency and high temperature electromechanical transducers.

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