Recent Investigations on Grain Boundary Relaxation

2012 ◽  
Vol 184 ◽  
pp. 33-41 ◽  
Author(s):  
Q.P. Kong ◽  
W.B. Jiang ◽  
P. Cui ◽  
Qian Feng Fang
Keyword(s):  
Internal Friction ◽  
Grain Boundary ◽  
High Purity ◽  
Compensation Effect ◽  
Coupling Effect ◽  
Internal Friction Peak ◽  
Individual Behaviors ◽  
Different Types ◽  
Boundary Relaxation ◽  
The Individual

In recent years, we have investigated the grain boundary (GB) internal friction in high-purity Al bicrystals with a wide variety of misorientations of tilt and twist GBs. The main results are reviewed and divided into the following sections: (1) the origin of the GB internal friction peak; (2) the individual behaviors of different types of GBs; and (3) the coupling effect and compensation effect involved in GB relaxation.

scholarly journals The Internal Friction of Single Crystals, Bicrystals and Polycrystals of Pure Magnesium

2015 ◽  
Vol 60 (1) ◽  
pp. 371-375 ◽  
Author(s):  
W.B. Jiang ◽  
Q.P. Kong ◽  
L.B. Magalas ◽  
Q.F. Fang
Keyword(s):  
Activation Energy ◽  
Internal Friction ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Room Temperature ◽  
Internal Friction Peak ◽  
Self Diffusion ◽  
Boundary Relaxation ◽  
The Difference

Abstract The internal friction of magnesium single crystals, bicrystals and polycrystals has been studied between room temperature and 450°C. There is no internal friction peak in the single crystals, but a prominent relaxation peak appears at around 160°C in polycrystals. The activation energy of the peak is 1.0 eV, which is consistent with the grain boundary self-diffusion energy of Mg. Therefore, the peak in polycrystals can be attributed to grain boundary relaxation. For the three studied bicrystals, the grain boundary peak temperatures and activation energies are higher than that of polycrystals, while the peak heights are much lower. The difference between the internal friction peaks in bicrystals and polycrystals is possibly caused by the difference in the concentrations of segregated impurities in grain boundaries.

Damping in AZ31 ECAP-Processed Alloy

2008 ◽  
Vol 137 ◽  
pp. 181-188 ◽  
Author(s):  
Tatiana V. Ivleva ◽  
Jürgen Göken ◽  
Igor S. Golovin ◽  
Zuzana Zuberova ◽  
Manuel Maikranz-Valentin ◽  
...  
Keyword(s):  
Internal Friction ◽  
Grain Boundary ◽  
Equal Channel Angular Pressing ◽  
Internal Friction Peak ◽  
Angular Pressing ◽  
Boundary Relaxation ◽  
Hot Rolled

Study of anelasticity in AZ31 magnesium-based alloy in initial (hot-rolled at 370 оС) condition and after one and four passes of equal channel angular pressing is carried out. An internal friction peak was found at 170 °C at a frequency f of about 1 Hz. Two possible mechanisms of this peak are discussed: it is suggested that the peak origin is the grain boundary relaxation.

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.

On the grain boundary internal friction peak of ?-brasses

1990 ◽  
Vol 25 (1) ◽  
pp. 519-521
Author(s):  
Z. M. Farid ◽  
S. Saleh ◽  
S. A. Mahmoud
Keyword(s):  
Internal Friction ◽  
Grain Boundary ◽  
Internal Friction Peak

Grain Boundary Relaxation in a Fe-Cr-Al Alloy

2011 ◽  
Vol 415-417 ◽  
pp. 2134-2137
Author(s):  
Zheng Cun Zhou ◽  
Q. Z. Wang ◽  
J. Du ◽  
H. Yang ◽  
Y.J. Yan
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Internal Friction ◽  
Grain Boundary ◽  
Relaxation Peak ◽  
Al Alloy ◽  
Relaxation Strength ◽  
Exponential Factor ◽  
Friction Temperature ◽  
Boundary Relaxation

The features of grain boundary relaxation of a (wt.%)Fe-25Cr-5Al alloy have been investigated using a multifunction internal friction apparatus. The grain boundary relaxation peak appears at about 630oC on the internal friction-temperature curves for the alloy. The peak temperature shifts toward high temperature with increasing frequency. In terms of Arrihenius relation, the activation energy is calculated to be 4.07(±0.15)eV and the pre-exponential factor is 6.2×10-24±1s. Grain boundary relaxation strength remarkably decreases with increasing grain size. When grain size reaches 520μm, the grain boundary relaxation peak almost disappears.

Sign in / Sign up

Export Citation Format

Share Document