Internal friction associated with the premartensitic transformation and twin boundary motion of Ni50+xMn25−xGa25 (x = 0−2) alloys

2013 ◽  
Vol 113 (10) ◽  
pp. 103502 ◽  
Author(s):  
Junyi Liu ◽  
Jingmin Wang ◽  
Chengbao Jiang ◽  
Huibin Xu
Keyword(s):  
Internal Friction ◽  
Twin Boundary ◽  
Boundary Motion

Real Structure and Internal Friction of Boron Doped with Zirconium

1987 ◽  
Vol 97 ◽  
Author(s):  
G. Sh. Darsavelidze ◽  
G. V. Tsagareishvili ◽  
M. E. Antadze ◽  
O. A. Tsagareishvili ◽  
A. G. Khvedelidze ◽  
...  
Keyword(s):  
Internal Friction ◽  
Twin Boundary ◽  
Boundary Motion ◽  
Continuous Change ◽  
Elastic Fields ◽  
Linear Defects ◽  
Boron Doped ◽  
Diffraction Patterns ◽  
High Level ◽  
Simulated Analysis

ABSTRACTThe nature of interaction of point and linear defects in semiconductor boron doped with zirconium (∼ 1.5% at.) has been studied using electron microscope and internal friction methods. It was shown that doping with zirconium promoted the multiplication of polysynthetic twins and stacking faults. A computer simulated analysis of diffraction patterns was performed in terms of trigonal presentation. At the frequency of free torsional vibrations of ∼ 1Hz a high level of internal friction with maxima at 250, 300–320 and 380–420°C was revealed. It is supposed that the maxima are respectively due to: the twin-boundary motion accompanied by breaking of intericosahedral bonds (a); the process of ordering-disordering of atoms in the impurity atmospheres under the continuous change of the temperature and elastic fields of moving twinning dislocations in the {100} system (b); the impurity controlled twin-boundary motion in the {511} system.

Effect of H-Doping on Damping Capacity of Various NiTi-Based Alloys at kHz Frequencies

2006 ◽  
Vol 128 (3) ◽  
pp. 254-259 ◽  
Author(s):  
B. Coluzzi ◽  
A. Biscarini ◽  
G. Mazzolai ◽  
F. M. Mazzolai ◽  
A. Tuissi
Keyword(s):  
Internal Friction ◽  
Twin Boundary ◽  
Room Temperature ◽  
Mechanical Energy ◽  
Noise Pollution ◽  
Metal Alloy ◽  
Maximum Efficiency ◽  
Damping Capacity ◽  
Good Opportunity ◽  
Hydrogen Doping

The internal friction Q−1 and the Young’s modulus E of NiTi based alloys have been measured as a function of temperature after various thermomechanical and hydrogen-doping treatments given to the materials. Hydrogen is found to play a major role introducing tall damping peaks associated with Snoek-type and H-twin boundary relaxations. Levels of Q−1 as high as 0.08 have been detected, which are among the highest to date measured in metal alloy systems. For appropriate alloy compositions, these peaks occur at around room temperature (for acoustical frequencies), thus providing a good opportunity to reduce machinery vibrations and noise pollution. In the paper, the conditions are highlighted under which maximum efficiency can be reached in the conversion of mechanical energy into heat.

scholarly journals Effect of Twin Boundary Motion and Dislocation-Twin Interaction on Mechanical Behavior in Fcc Metals

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2238
Author(s):  
Jaber Rezaei Mianroodi ◽  
Bob Svendsen
Keyword(s):  
Twin Boundary ◽  
Partial Dislocation ◽  
Shear Loading ◽  
Dislocation Nucleation ◽  
The Other ◽  
Boundary Motion ◽  
Normal Loading ◽  
Fcc Metals ◽  
Boundary Orientation ◽  
Normal Twin

The interplay of interface and bulk dislocation nucleation and glide in determining the motion of twin boundaries, slip-twin interaction, and the mechanical (i.e., stress-strain) behavior of fcc metals is investigated in the current work with the help of molecular dynamics simulations. To this end, simulation cells containing twin boundaries are subject to loading in different directions relative to the twin boundary orientation. In particular, shear loading of the twin boundary results in significantly different behavior than in the other loading cases, and in particular to jerky stress flow. For example, twin boundary shear loading along ⟨ 112 ⟩ results in translational normal twin boundary motion, twinning or detwinning, and net hardening. On the other hand, such loading along ⟨ 110 ⟩ results in oscillatory normal twin boundary motion and no hardening. As shown here, this difference results from the different effect each type of loading has on lattice stacking order perpendicular to the twin boundary, and so on interface partial dislocation nucleation. In both cases, however, the observed stress fluctuation and “jerky flow” is due to fast partial dislocation nucleation and glide on the twin boundary. This is supported by the determination of the velocity and energy barriers to glide for twin boundary partials. In particular, twin boundary partial edge dislocations are significantly faster than corresponding screws as well as their bulk counterparts. In the last part of the work, the effect of variable twin boundary orientation in relation to the loading direction is investigated. In particular, a change away from pure normal loading to the twin plane toward mixed shear-normal loading results in a transition of dominant deformation mechanism from bulk dislocation nucleation/slip, to twin boundary motion.

Real-time observation of twin boundary motion in organic crystal (TMTSF)2X

2001 ◽  
Vol 251 (1) ◽  
pp. 199-205 ◽  
Author(s):  
Kazushige Kawabata ◽  
Yasuyoshi Hosokawa ◽  
Takashi Kawauchi ◽  
Takashi Sambongi
Keyword(s):  
Real Time ◽  
Twin Boundary ◽  
Organic Crystal ◽  
Boundary Motion ◽  
Time Observation ◽  
Real Time Observation

Nonuniform twin-boundary motion in Ni–Mn–Ga single crystals

2004 ◽  
Vol 84 (20) ◽  
pp. 4071-4073 ◽  
Author(s):  
Miguel A. Marioni ◽  
Samuel M. Allen ◽  
Robert C. O’Handley
Keyword(s):  
Single Crystals ◽  
Twin Boundary ◽  
Boundary Motion

Theoretical Study of Twin Boundary Motion in Heusler Ni-Mn-Ga Alloys Using Monte Carlo Method

2012 ◽  
Vol 190 ◽  
pp. 327-330
Author(s):  
K.I. Kostromitin ◽  
Vasiliy D. Buchelnikov ◽  
V.V. Sokolovskiy ◽  
P. Entel
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Monte Carlo Simulations ◽  
Twin Boundary ◽  
Constant Temperature ◽  
Theoretical Study ◽  
Heusler Alloys ◽  
Boundary Motion ◽  
Different Temperatures

The twin boundary motion in Ni-Mn-Ga Heusler alloys has been investigated using Monte Carlo simulations. The Hamiltonian of system includes magnetic and elastic parts and two magnetoelastic terms. It is shown that the twin boundary shifts in a magnetic field at the constant temperature. The spin and strain volume fractions have been obtained at different temperatures.

Temperature dependence of single twin boundary motion in Ni–Mn–Ga martensite

2011 ◽  
Vol 98 (14) ◽  
pp. 141902 ◽  
Author(s):  
L. Straka ◽  
H. Hänninen ◽  
O. Heczko
Keyword(s):  
Temperature Dependence ◽  
Twin Boundary ◽  
Boundary Motion

The effect of loading rate on characteristics of type II twin boundary motion in Ni-Mn-Ga

2018 ◽  
Vol 144 ◽  
pp. 44-47 ◽  
Author(s):  
Noam Zreihan ◽  
Eilon Faran ◽  
Doron Shilo
Keyword(s):  
Twin Boundary ◽  
Loading Rate ◽  
Boundary Motion ◽  
Type Ii

Numerical Simulation of Twin-Twin Interaction in Magnetic Shape-Memory Alloys

2008 ◽  
Vol 1090 ◽  
Author(s):  
Markus Chmielus ◽  
David Carpenter ◽  
Alan Geleynse ◽  
Michael Hagler ◽  
Rainer Schneider ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shear Strain ◽  
Twin Boundary ◽  
Boundary Motion ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Line Defects

AbstractTwin boundary motion is the mechanism that drives the plastic deformation in magnetic shape memory alloys (MSMAs), and is largely dependent on the twin microstructure of the MSMA. The twin microstructure is established during the martensitic transformation, and can be influenced through thermo-magneto-mechanical training. For self-accommodated and ineffectively trained martensite, twin thickness and magnetic-field-induced strain (MFIS) are very small. For effectively trained crystals, a single crystallographic domain may comprise the entire sample and MFIS reaches the theoretical limit. In this paper, a numerical simulation is presented describing the twin microstructures and twin boundary motion of self-accommodated martensite using disclinations and disconnections (twinning dislocations). Disclinations are line defects such as dislocations, however with a rotational displacement field. A quadrupole solution was chosen to approximate the defect structure where two quadrupoles represent an elementary twin double layer unit. In the simulation, the twin boundary was inclined to the twinning plane which required the introduction of twinning disconnections, which are line defects with a stress field similar to dislocations. The shear stress - shear strain properties of self-accommodated martensite were analyzed numerically for different initial configurations of the twin boundary (i.e. for different initial positions of the disconnections). The shear stress - shear strain curve was found to be sensitive to the initial configuration of disconnections. If the disconnections are very close to boundaries of hierarchically higher twins – such as is the case for self-accommodated martensite, there is a threshold stress for twin-boundary motion. If the disconnections are spread out along the twin boundary, twinning occurs at much lower stress.

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