The role of vacancies in the mobility of dislocations and grain boundaries in magnesium

Lambri, O.A.; Massot, M.; Riehemann, W.; Lucioni, E.J.; Plazaola, F.; Garcı́a, J.A.

doi:10.1002/pssa.200622336

Cited by 17 publications

(17 citation statements)

References 38 publications

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“…The results for the unalloyed magnesium are also in agreement with previous results, where a temperature higher than 500 K was reported for the generation of new vacancies which assist the dislocation movement. 7) We can say, as summary for this Section, that the excess of vacancies out of thermodynamic equilibrium produced by plastic deformation at RT, are consumed up to around 550 K, leading to a decrease in the mobility of dislocations in WE 43 alloys. The damping spectra in this deformed alloy and consequently the mobility of dislocations at temperatures over 550 K, is assisted by the new vacancies in thermal equilibrium generated during heating in the MS tests.…”

Section: The 10% Plastically Deformed Samplesmentioning

confidence: 88%

“…The average cooling rates were 14 and 3 K min À1 , respectively. 7,11) During the run-up in temperature, damping (Q À1 ), was calculated from the slope of the straight line which results from the least squares fitting of the natural logarithm of all the decaying areas versus time, such that…”

Section: Measurements 221 Mechanical Spectroscopymentioning

confidence: 99%

“…27,28) The temperature, where the slope of S increases (650 K) is around 100 K higher than the temperatures where the grain boundary relaxation in WE43 alloy appears. 7,8,11,12,29,30) The damping peaks related to the grain boundary relaxation happen between 450 K and 550 K. The temperatures of these peaks are approximately the followings: 450 K for the solvent grain boundary peak, 500 K for the solute grain boundary peak and 550 K for the grain boundary peak related to particles or obstacles at the grain boundaries. Therefore, at temperatures of around 650 K, i.e.…”

Section: Positron Annihilation Lifetime Spectroscopymentioning

confidence: 99%

“…New vacancies generated by heating at temperatures over 500 K are required for unpinning dislocation and grain-boundary structures. 7) Alloying commercial pure magnesium improves its poor strength, leading to the decrease in the damping capacity due to weak dislocation pinning. [1][2][3][4][5][6][7][8] Among commercial magnesium alloys, WE43 (Mg, 4 mass% Y, 3.4 mass% Nd, 0.7 mass% Zr) alloy has some of the best mechanical properties at high temperatures and exhibits good corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

“…7) Alloying commercial pure magnesium improves its poor strength, leading to the decrease in the damping capacity due to weak dislocation pinning. [1][2][3][4][5][6][7][8] Among commercial magnesium alloys, WE43 (Mg, 4 mass% Y, 3.4 mass% Nd, 0.7 mass% Zr) alloy has some of the best mechanical properties at high temperatures and exhibits good corrosion resistance. 1,2,4) In addition, WE43 alloy presents age-hardening by ageing at 473 K. 9,10) Moreover, the development of a precipitation process beginning at temperatures of about 640 K has been reported more recently.…”

Section: Introductionmentioning

confidence: 99%

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Dislocation Movement in WE43 Magnesium Alloy during Recovery and Recrystallisation

Lambri

Garcı́a²,

Riehemann

et al. 2011

Mater. Trans.

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The mobility of dislocations has been investigated in WE43 magnesium alloy during recovery and recrystallisation for samples deformed plastically, at different degrees of plastic deformation and temperatures. The dislocation density decreases within the temperature range 550 K-650 K, in good agreement with the characteristic recovery temperature of this alloy, 630 K. New dislocations located at the grain boundaries start their movement from 650 K onwards. During recrystallisation, which has a characteristic temperature of around 700 K, the density of dislocations decreases and the possibility of movement of the dislocations also decreases, due to the development of internal stresses during the growth of new strain-free grains.The excess of vacancies promoted by the plastic deformation in cold worked samples is consumed up to temperatures of 550 K. New thermal vacancies which assist the movement of grain boundaries and dislocations are created after annealing at temperature above 650 K. Hot worked samples which exhibit dynamic recovery or recrystallisation, depending on the degree of plastic deformation; have a structure with both a scarce dislocations mobility and also a small dislocations density.

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Section: The 10% Plastically Deformed Samplesmentioning

confidence: 88%

Section: Measurements 221 Mechanical Spectroscopymentioning

confidence: 99%

Section: Positron Annihilation Lifetime Spectroscopymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Dislocation Movement in WE43 Magnesium Alloy during Recovery and Recrystallisation

Lambri

Garcı́a²,

Riehemann

et al. 2011

Mater. Trans.

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Mechanical energy losses in commercial crosslinked low‐density polyethylene in the temperature range between 200 and 400 K

Lambri

Bonifacich

Garcı́a

et al. 2019

J of Applied Polymer Sci

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Aging treatments in water and in air and controlled neutron irradiation were performed on commercial crosslinked lowdensity polyethylene (XLPE) for promoting different mesostructural arrangements of crystallites and crosslinking degree. Infrared spectroscopy, differential scanning calorimetry, differential thermal analysis, thermogravimetry, and dynamic mechanical analysis were used as characterization techniques. The relaxation peak related to the mobility of the grain boundaries from crystalline zones in XLPE was identified at around 260 K (at 7 Hz), involving an activation energy of 90 AE 4 kJ mol −1 . The usual equation for describing the grain boundary mobility in metals involving the movement of grain boundary dislocations was adapted for studying the mobility of the boundaries among the crystalline zones, successfully. In addition, a new mechanical relaxation peak that appears at around 300 K (at 7 Hz), which involves an activation energy of 94 AE 5 kJ mol −1 , was found. The driving force controlling this peak was determined as the dragging of the polymer chains at the amorphous zones adjacent to the crystals controlled by the mobility of the crystallites boundaries. The chains movement was done with break away from the physical pinning points.

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Strain Amplitude Dependence of Internal Friction in a Cu–Al–Mn Shape Memory Alloy

Jiao

Yin

Zhang

et al. 2022

Physica Status Solidi (a)

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Strain amplitude (SA) dependence of internal friction (IF) in a Cu–Al–Mn shape memory alloy (SMA) is investigated. Microstructure observation is conducted with the aim to clarify related mechanisms. It is found that the IF measured during the continuous heating process shows a nonmonotonous dependence on SA, that is, the IF increases first and then decreases. The increase of IF can be attributed to the mergence of martensite laths promoted by the reorientation of martensite variants, whereas the decrease of IF is related to the decrease in the density of moveable interfaces. The isothermal IF measured at low temperatures increases monotonously with the increase in SA, because the density of movable interfaces and the sliding distance of these interfaces in the tangential direction increase. Thermal cycles can significantly improve the isothermal IF because of the annihilation of quenched‐in vacancies and the reorientation of martensite variants. At around 240 °C, the isothermal IF in all specimens shows a nonmonotonous dependence on SA, which can be ascribed to the dragging effect of quenched‐in vacancies on dislocations and the breakaway of dislocations from these vacancies when the SA is high enough.

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The role of vacancies in the mobility of dislocations and grain boundaries in magnesium

Cited by 17 publications

References 38 publications

Dislocation Movement in WE43 Magnesium Alloy during Recovery and Recrystallisation

Dislocation Movement in WE43 Magnesium Alloy during Recovery and Recrystallisation

Mechanical energy losses in commercial crosslinked low‐density polyethylene in the temperature range between 200 and 400 K

Strain Amplitude Dependence of Internal Friction in a Cu–Al–Mn Shape Memory Alloy

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