The role of grain boundary sliding and intragranular deformation mechanisms for a steady stage of superplastic flow for Al–Mg-based alloys

Deformation mechanisms occurring by tension of ultrafine-grained aluminum processed by equal-channel angular pressing at room temperature are investigated using comparative study of the microstructure before and after tensile testing as well as deformation relief on the pre-polished surface of the sample tested. Deformation behavior and structure evolution during tension suggest development of grain boundary sliding in addition to intragrain dislocation slip. Contribution grain boundary sliding to the overall deformation calculated using the magnitude of shift of grains relative to each other is found to be ~40%.

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The Role of Diffusion Accommodation and Phase Boundary Wetting in the Deformation Behaviour of Ultrafine Grained Sn-Pb Eutectic

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.297-301.1002 ◽

2010 ◽

Vol 297-301 ◽

pp. 1002-1009 ◽

Cited By ~ 1

Author(s):

Faina Muktepavela ◽

R. Zabels

Keyword(s):

Grain Boundary ◽

Diffusion Processes ◽

Deformation Behaviour ◽

Grain Boundary Sliding ◽

Ultrafine Grained ◽

Interphase Boundaries ◽

Boundary Sliding ◽

High Homologous Temperature ◽

Microscopy Techniques

Mechanical properties, microstructure of the Sn–38wt. %Pb eutectic and the development of deformation - induced diffusion processes on interphase boundaries (IB) were investigated. Experiments were carried out both in deformed and annealed states of eutectic using micro- and nanoindentation, SEM, AFM and optical microscopy techniques. It was found that the deformation of the annealed alloy is localized at the Pb/Sn interphase boundaries and occurs by grain boundary sliding (GBS) accompanied by sintering micropore processes under the action of the capillary forces on the Pb/Sn IB. During severe plastic deformation of Sn-Pb eutectic phase transition in the Sn grain boundary occurs. This deformation-induced process takes place due to the wetting of tin with Pb. These diffusion accommodation processes (sintering and wetting) are facilitated by the low values of the Pb/Sn interphase energy (0.07 J/m2). Wetting is thermodynamically favourable because the condition γgb > 2 γib is satisfied and it is also kinetically allowed due to the relatively high homologous temperature (> 0.5•Tm). The obtained values of the nanohardness and elastic modulus evidence that the IBs in the Sn–Pb eutectic have to be considered as a separate quasi-phase with its own properties.

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The role of grain-boundary sliding in the creep of polycrystals

Acta Metallurgica ◽

10.1016/0001-6160(76)90107-3 ◽

1976 ◽

Vol 24 (8) ◽

pp. 725-729 ◽

Cited By ~ 19

Author(s):

M.V. Speight

Keyword(s):

Grain Boundary ◽

Grain Boundary Sliding ◽

Boundary Sliding

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Role of Vacancies and Solute Atoms on Grain Boundary Sliding

MRS Proceedings ◽

10.1557/proc-601-169 ◽

1999 ◽

Vol 601 ◽

Author(s):

J.S. Vetrano ◽

C.H. Henager ◽

E.P. Simonen

Keyword(s):

Grain Boundary ◽

Solute Atom ◽

Vacancy Concentration ◽

Grain Boundary Sliding ◽

Fine Grained ◽

Grain Boundary Plane ◽

Transmission Electron ◽

Boundary Sliding ◽

Solute Atoms

AbstractIt is necessary for grain boundary dislocations to slide and climb during the grain boundary sliding process that dominates fine-grained superplastic deformation. The process of climb requires either an influx of vacancies to the grain boundary plane or a local generation of vacancies. Transmission electron microscopy (TEM) observations of grain boundaries in superplastically deformed Al-Mg-Mn alloys quenched under load from the deformation temperature have revealed the presence of nano-scale cavities resulting from a localized supersaturation of vacancies at the grain boundary. Compositional measurements along interfaces have also shown an effect of solute atoms on the local structure. This is shown to result from a coupling of vacancy and solute atom flows during deformation and quenching. Calculations of the localized vacancy concentration indicate that the supersaturation along the grain boundary can be as much as a factor often. The effects of the local supersaturation and solute atom movement on deformation rates and cavity nucleation and growth will be discussed.

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Temperature Dependence of Compressive Deformation Behavior of Mg89Zn4Y7 Extruded LPSO-Phase Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.607 ◽

2010 ◽

Vol 654-656 ◽

pp. 607-610 ◽

Cited By ~ 6

Author(s):

Koji Hagihara ◽

Akihito Kinoshita ◽

Yuya Sugino ◽

Michiaki Yamasaki ◽

Yoshihito Kawamura ◽

...

Keyword(s):

Grain Size ◽

Grain Boundary ◽

Temperature Dependence ◽

Yield Stress ◽

Deformation Behavior ◽

Grain Boundary Sliding ◽

Deformation Mechanisms ◽

Petch Relationship ◽

Lpso Phase ◽

Boundary Sliding

Deformation mechanisms of Mg89Zn4Y7 (at.%) extruded alloy, which is mostly composed of LPSO-phase, was investigated focusing on their temperature dependence. The yield stress of as-extruded alloy showed extremely high value of ~480 MPa at RT, but it largely decreased to ~130 MPa at 300 °C. The decreasing rate of the yield stress could be significantly reduced, however, by the annealing of specimen at 400 °C, by suppressing the microyielding which is considered to occur related by the grain boundary sliding in restricted regions. The yield stress of the annealed specimens with random textures could be estimated by the Hall-Petch relationship by regarding the length of long-axis of plate-like grains as a grain size between RT and 300 °C. The yield stress of the annealed specimens maintained high values even at 200°C, but it also showed large decreases at 300 °C.

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