Mechanical Spectroscopy of the Fe-25Al-Cr Alloys in Medium Temperature Range

2008 ◽  
Vol 137 ◽  
pp. 99-108 ◽  
Author(s):  
Igor S. Golovin ◽  
Andre Rivière
Keyword(s):  
Internal Friction ◽  
Intermetallic Compounds ◽  
Activation Parameters ◽  
Transient Effects ◽  
Mechanical Spectroscopy ◽  
Internal Friction Peak ◽  
Medium Temperature ◽  
Atom Diffusion ◽  
Cr Content ◽  
Fe3al Intermetallic

Fe3Al intermetallic compounds and several (Fe,Cr)3Al alloys with Cr content from 3 to 25 % have been studied using isothermal mechanical spectroscopy. The Zener relaxation caused by reorientation of pairs of substitute atoms in Fe is observed in all studied alloys and used to evaluate the activation parameters of Al (Cr) atom jumps in Fe. The second internal friction peak at higher temperatures was observed only in Cr containing alloys. Isothermal mechanical spectroscopy (employed frequency from 10-4 to 102 Hz) gives some advantages as compared with ordinary techniques, i.e. study of anelasticity as a function of temperature. It allows to avoid transient effects and to measure materials in a state close to equilibrium. This allows to distinguish clearly between Al atom diffusion in Fe3Al in B2 and D03 states (activation energies for Fe – 26 Al in the B2 range the HB2 ≈ 235 kJ/mol, and in the D03 ordered range the HD03 ≈ 286 kJ/mol). Effect of chromium on the Zener relaxation is analysed.

High-Temperature Mechanical Relaxation due to Dislocation Motion inside Dislocation Networks

2008 ◽  
Vol 137 ◽  
pp. 21-28 ◽  
Author(s):  
Andre Rivière ◽  
Michel Gerland ◽  
Veronique Pelosin
Keyword(s):  
Internal Friction ◽  
Relaxation Effect ◽  
Dislocation Motion ◽  
Relaxation Peak ◽  
Mechanical Relaxation ◽  
In Situ Tem ◽  
Mechanical Spectroscopy ◽  
Internal Friction Peak ◽  
First Case ◽  
Dislocation Walls

Internal friction peaks observed in single or polycrystals are clearly due to a dislocation relaxation mechanism. Because a sample observed by transmission electron microscopy (TEM) often exhibits in the same time various dislocation microstructures (isolated dislocations, dislocation walls, etc.) it is very difficult to connect the observed relaxation peak with a particular dislocation microstructure. Using isothermal mechanical spectroscopy (IMS), it is easier to compare, for instance, the evolution of a relaxation peak with measurement temperature to the microstructural evolution observed by in-situ TEM at the same temperatures. IMS was used to study a relaxation peak in a 5N aluminium single crystal firstly 1% cold worked and then annealed at various temperatures. TEM experiments performed in the same material at various temperatures equal to the temperatures used for the damping experiments made possible to link this internal friction peak with a relaxation effect occurring inside dislocation walls. In two other experiments in a 4N aluminium polycrystal and in a metal matrix composite with SiC whiskers, it is shown that the observed relaxation peaks are connected to the motion of dislocations inside polygonization boundaries in the first case and in dislocation pile-ups around each whisker in the second one. Theoretical models proposed to explain such relaxation peaks due to a dislocation motion inside a dislocation wall or network are discussed.

Mechanical Spectroscopy of Hyperstabilized Martensites

2012 ◽  
Vol 184 ◽  
pp. 355-360 ◽  
Author(s):  
Sergey Kustov ◽  
R. Santamarta ◽  
E. Cesari ◽  
K. Sapozhnikov ◽  
V. Nikolaev ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Internal Friction ◽  
Essential Role ◽  
Parent Phase ◽  
Martensitic Transformation Temperature ◽  
Mechanical Spectroscopy ◽  
Internal Friction Peak ◽  
Pinning Effect ◽  
The One

The internal friction of the hyperstabilized martensite demonstrates very low values, both above and below the nominal martensitic transformation temperature, due to a pronounced pinning effect. Over a wide temperature range it is comparable with the level of damping in the parent phase. A study of the temperature dependence of the non-linear ultrasonic internal friction and its strain amplitude hysteresis indicates that the diffusion, assisted by dislocations/interfaces, is quite pronounced and in Ni-Fe-Ga and Cu-Al-Be alloys it operates at temperatures around 20 K. The renucleation of the lamellar parent phase during the reverse martensitic transformation close to 600 K is accompanied by an internal friction peak which demonstrates a substantial transitory contribution. After renucleation of the parent phase the samples recover a conventional martensitic transformation with the internal friction level in the martensite comparable to the one in non-stabilized samples. Observations of a relaxation peak in the parent phase of different alloys for temperatures just below the renucleation stage of the reverse transformation point to the essential role of diffusion in the nucleation of the parent phase in hyperstabilized martensites.

scholarly journals Low-Frequency Mechanical Spectroscopy of Lanthanum Cobaltite Based Mixed Conducting Oxides

2016 ◽  
Vol 61 (3) ◽  
pp. 1733-1738
Author(s):  
Xiu Sheng Wu ◽  
Ju Fang Cao ◽  
Zhi Jun Chen ◽  
Wei Liu
Keyword(s):  
Phase Transition ◽  
Internal Friction ◽  
Domain Walls ◽  
Low Frequency ◽  
Partial Substitution ◽  
Cubic Phase ◽  
Mechanical Spectroscopy ◽  
Internal Friction Peak ◽  
Lanthanum Cobaltite ◽  
Conducting Oxides

Abstract The low-frequency mechanical spectra of lanthanum cobaltite based mixed conducting oxides have been measured using a computer-controlled inverted torsion pendulum. The results indicate that the internal friction spectra and shear modulus depend on the Sr doping contents (x). For undoped samples, no internal friction peak is observed. However, for La0.8Sr0.2CoO3‒δ, three internal friction peaks (P2, P3 and P4) are observed. In addition to these peaks, two more peaks (P0 and P1) are observed in La0.6Sr0.4CoO3‒δ. The P0 and P1 peaks show characteristics of a phase transition, while the P2, P3 and P4 peaks are of relaxation-type. Our analysis suggests that the P0 peak is due to a phase separation and the P1 peak is related to the ferromagnetic–paramagnetic phase transition. The P2, P3 and P4 peaks are associated with the motion of domain walls. The formation of this kind of domain structure is a consequence of a transformation from the paraelastic cubic phase to the ferroelastic rhombohedral phase. With partial substitution of Fe for Co, only one peak is observed, which is discussed as a result of different microstructure.

scholarly journals Mechanical Spectroscopy Of Equal-Channel Angular Pressed Fe-Cr Alloys And Tungsten

2015 ◽  
Vol 60 (3) ◽  
pp. 2101-2106 ◽  
Author(s):  
Ting Hao ◽  
Haiyin Tang ◽  
Weibin Jiang ◽  
Xianping Wang ◽  
Qianfeng Fang
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Grain Boundary ◽  
Microstructural Stability ◽  
Mechanical Spectroscopy ◽  
Internal Friction Peak ◽  
Static Recovery ◽  
Microstructural Transition ◽  
Deformed State ◽  
Friction Measurements

Abstract Internal friction technique was used to investigate the microstructural stability of equal-channel angular pressed (ECAP) 9Cr1Mo steel (T91), Fe-18wt.%Cr alloy, and pure W. Several non-relaxation internal friction peaks are observed in three ECAP-strained specimens, which are related to the microstructural transition from a severely deformed state to a static recovery state of dislocations, and to recrystallized state. Along with the disappearance of the P1 peak, another relaxation internal friction peak P2 is observed during the second heating run only in Fe-18wt.%Cr alloy, and it does not disappear even during subsequent third heating run. This peak is not observed in T91 steel and W. The P2 peak is likely associated with a process of grain boundary (GB) sliding. Unlike T91, no abundant carbide precipitates distribute on GBs to pin GB and repulse GB sliding, thus, the P2 peak only occurs in Fe-18wt.%Cr alloy. It is concluded that high-temperature internal friction measurements are required to detect the grain boundary peak in pure W.

Development of the Snoek Anelastic Relaxation Correlated with Oxygen in β-Ti Alloys

2019 ◽  
Vol 298 ◽  
pp. 59-63 ◽  
Author(s):  
Zheng Cun Zhou ◽  
J. Du ◽  
S.Y. Gu ◽  
Y.J. Yan
Keyword(s):  
Internal Friction ◽  
Physical And Mechanical Properties ◽  
Peak Height ◽  
Relaxation Peak ◽  
Interstitial Oxygen ◽  
Internal Friction Peak ◽  
Β Phase ◽  
Ti Alloys ◽  
Interstitial Atoms ◽  
The Stability

The β-Ti alloys exhibit excellent shape memory effect and superelastic properties. The interstitial atoms in the alloys have important effect on their physical and mechanical properties. For the interstitial atoms, the internal friction technique can be used to detect their distributions and status in the alloys. The anelastic relaxation in β-Ti alloys is discussed in this paper. β-Ti alloys possesses bcc (body center body) structure. The oxygen (O) atoms in in the alloys is difficult to be removed. The O atoms located at the octahedral sites in the alloys will produce relaxation under cycle stress. In addition, the interaction between the interstitial atoms and substitute atoms, e.g., Nb-O,Ti-O can also produce relaxation. Therefore, the observed relaxational internal friction peak during the measuring of internal friction is widened. The widened multiple relaxation peak can be revolved into Debye,s elemental peaks in Ti-based alloys. The relaxation peak is associated with oxygen movements in lattices under the application of cycle stress and the interactions of oxygen-substitute atoms in metastable β phase (βM) phase for the water-cooled specimens and in the stable β (βS) phase for the as-sintered specimens. The damping peak height is not only associated with the interstitial oxygen, but also the stability and number of βM in the alloys.

Mechanical Spectroscopy Study on the Light Soaking Effect on Hydrogenated Amorphous Silicon

2012 ◽  
Vol 184 ◽  
pp. 416-421 ◽  
Author(s):  
H. Mizubayashi ◽  
I. Sakata ◽  
H. Tanimoto
Keyword(s):  
Internal Friction ◽  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Wide Distribution ◽  
Activation Energies ◽  
Mechanical Spectroscopy ◽  
Induced Changes ◽  
Mild Temperature ◽  
Hydrogenated Amorphous

For hydrogenated amorphous silicon (a-Si:H) films deposited at temperatures between 423 K and 623 K (a-Si:H423Kand so on), the light-induced changes in the internal friction between 80 K and 400 K were studied. The internal friction is associated with H2motion in microvoid networks, and shows the mild temperature dependence between about 80 K and 300 K (Q-180-300K) and the almost linear increase above 300 K (Q-1>300K). BothQ-180-300KandQ-1>300Kdecrease with increasing the deposition temperature, and show the mild temperature dependence ina-Si:H623K. The white light soaking with 100 mW/cm2(WLS100and so on) below 300 K caused a change inQ-180-300Kand no changes inQ-1>300K, respectively, and the light-induced changes inQ-180-300Krecovered after annealing at 423 K. The wide distribution of activation energies for H2motions between microvoids indicate that most of neighboring microvoids are connected through windows, i.e., the microvoid networks are existing ina-Si:H, and the spatially loose or solid structures are responsible for the low or high activation energies for the H2motion between microvoids, respectively. Furthermore, the light-induced hydrogen evolution (LIHE) was observed for WLS200to WLS400in a vacuum between 400 and 500 K, resulting in the disappearance of the internal friction due to the H2motion in the microvoid network.

scholarly journals On Glass Forming Ability of Bulk Metallic Glasses by Relating the Internal Friction Peak Value

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 767
Author(s):  
Xianfeng Zhang ◽  
Xiao Cui ◽  
Zhuotong Du ◽  
Fangqiu Zu ◽  
Jinjing Li ◽  
...  
Keyword(s):  
Internal Friction ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Glass Forming Ability ◽  
Liquid Region ◽  
Internal Friction Peak ◽  
Glass Forming ◽  
Constituent Elements ◽  
Valid Criterion ◽  
Peak Value

The internal friction (IF) behaviors of a series of LaCe-, Zr-, and La-based bulk metallic glasses (BMGs) were studied by a computer-controlled, conventional inverted torsion pendulum. The results indicate that with an increasing temperature, the IF also increases gradually in the supercooled liquid region, followed by a decrease caused by crystallization. BMGs with a good glass forming ability (GFA) usually possess a high IF peak value for an alloy system with the same constituent elements. Furthermore, the magnitude of the IF value (Qi−1) of the inflection point is an efficient criterion of GFA. The Qi−1 value is a valid criterion under the conditions of identical constituent elements and different element contents. However, Qi−1 and GFA have no relationship among different alloy systems.

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