Change in the structural state of grain boundaries under high-rate mechanical loading

1999 ◽  
Vol 35 (6) ◽  
pp. 704-706
Author(s):  
S. G. Psakh'e ◽  
K. P. Zol'nikov ◽  
D. Yu. Saraev
Keyword(s):  
Grain Boundaries ◽  
Mechanical Loading ◽  
Structural State ◽  
High Rate

Influence of the grain size and structural state of grain boundaries on the parameter of low-temperature and high-rate superplasticity of nanocrystalline and microcrystalline alloys

2010 ◽  
Vol 52 (5) ◽  
pp. 1098-1106 ◽  
Author(s):  
V. N. Chuvil’deev ◽  
A. V. Shchavleva ◽  
A. V. Nokhrin ◽  
O. É. Pirozhnikova ◽  
M. Yu. Gryaznov ◽  
...  
Keyword(s):  
Grain Size ◽  
Low Temperature ◽  
Grain Boundaries ◽  
Structural State ◽  
High Rate

Radiation-Induced Minor Element Segregation at Austenitic Stainless Steel Grain Boundaries

1996 ◽  
Vol 439 ◽  
Author(s):  
E. P. Simonen ◽  
S. M. Bruemmer
Keyword(s):  
Grain Boundaries ◽  
Neutron Irradiation ◽  
Ion Irradiation ◽  
Austenitic Stainless Steels ◽  
Minor Element ◽  
High Rate ◽  
Rate Theory ◽  
Minor Elements ◽  
Radiation Induced ◽  
Irradiation Behavior

AbstractMeasurement of minor element compositions at irradiated grain boundaries in austenitic stainless steels indicates that Si is the only element that significantly responds to radiation-induced segregation. Other minor elements, such as P or S, do not exhibit elevated grain boundary concentrations after irradiation. A rate theory evaluation of segregation is in accord with ioninduced Si enrichment, but reveals complexities in the interpretation of extrapolating behavior from ion-irradiation to neutron-irradiation behavior. The model calibrated to measured high-rate, ioninduced segregation greatly overestimates measured low-rate, neutron-irradiation segregation of Si.

scholarly journals Formation of Nanolaminated Structure with Enhanced Thermal Stability in Copper

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2252
Author(s):  
Jianxin Hou ◽  
Xiuyan Li ◽  
Ke Lu
Keyword(s):  
Thermal Stability ◽  
Ambient Temperature ◽  
Grain Boundaries ◽  
Shear Deformation ◽  
Stacking Faults ◽  
High Rate ◽  
Nanostructured Metals ◽  
Partial Dislocations ◽  
Boundary Spacing ◽  
High Microhardness

Nanolaminated structure with an average boundary spacing of 67 nm has been fabricated in copper by high-rate shear deformation at ambient temperature. The nanolaminated structure with an increased fraction of low angle grain boundaries exhibits a high microhardness of 2.1 GPa. The structure coarsening temperature is 180 K higher than that of its equiaxial nanograined counterpart. Formation of nanolaminated structure provides an alternative way to relax grain boundaries and to stabilize nanostructured metals with medium to low stacking faults energies besides activation of partial dislocations.

Ferrian high sanidine in a lamproite from Cancarix, Spain

1993 ◽  
Vol 57 (387) ◽  
pp. 289-299 ◽  
Author(s):  
Kees Linthout ◽  
Wim J. Lustenhouwer
Keyword(s):  
Solid Solution ◽  
Structural State ◽  
Defect Structure ◽  
Diffusion Rate ◽  
High Rate ◽  
Nonstoichiometric Composition ◽  
Low Viscosity ◽  
High Diffusion Rate ◽  
Retrograde Boiling ◽  
Residual Melt

AbstractNa-poor, Fe-bearing high sanidine from a lamproite near Cancarix (Spain) has 2Vα‖(010) = 37-43° and C2/m, a = 8.598(15), b = 13.050(26), c = 7.209(17) Å, β = 116.00(18)° V = 727(2) Å3. Rims of sanidine crystals against vugs contain up to 60 mole % KFeSi3O8 and up to 10 at.% Si and 6 at.% K above the stoichiometric requirement; otherwise, they have up to 4 mole % □Si4O8 and 3 mole % K2O.Si4O8 in solid solution. Their MgO content may reach 0.46 wt.%. The skeletons of mm sized blocky crystals (Baveno habit) indicate formation under moderate undercooling at temperatures not much above 725°C Feldspar formation was facilitated by a high diffusion rate due to low viscosity in a highly perpotassic melt, supersaturated by pressure release and diopside fractionation, upon extrusion of a huge volume of lava in a crater. After titanian potassium-richterite largely filled the interstices in the sanidine fabric, crystals of dalyite (K2ZrSi6O15) and Fe-rich rims of sanidine and amphibole crystals were formed from an increasingly hydrous, silicic, ferric, and peralkaline residual melt. High rate nonequilibrium crystallisation caused the incorporation of excess SiO2 and K2O in the defect structure of the sanidine. Retrograde boiling initiated the escape of volatiles, causing the quenching, by which the disordered structural state and the nonstoichiometric composition of the sanidine were preserved.

scholarly journals Neural cell injury pathology due to high-rate mechanical loading

2021 ◽  
pp. 100034
Author(s):  
Jonathan B. Estrada ◽  
Harry C. Cramer ◽  
Mark T. Scimone ◽  
Selda Buyukozturk ◽  
Christian Franck
Keyword(s):  
Mechanical Loading ◽  
Cell Injury ◽  
Neural Cell ◽  
High Rate

Hot Deformation and Dynamic Recrystallization of the Beta Phase in Titanium Alloys

2012 ◽  
Vol 706-709 ◽  
pp. 127-134 ◽  
Author(s):  
Frank Montheillet ◽  
L. Pallot ◽  
David Piot
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Titanium Alloys ◽  
Grain Boundaries ◽  
Strain Range ◽  
Beta Phase ◽  
High Rate ◽  
Crystallographic Structure ◽  
Continuous Dynamic Recrystallization ◽  
Β Phase

Due to the high rate of dynamic recovery associated with the large stacking fault energy of the bcc structure, classical "discontinuous" dynamic recrystallization, occurring by nucleation and growth of new grains is not observed in the β phase of titanium alloys. Instead, the following mechanisms take place: at low and moderate strains (ε < 1), the original flattened (compression) or sheared (torsion) grains are still recognizable, although their boundaries are strongly serrated. In this strain range, grain size (thickness) results from both the convection and the migration of grain boundaries. At intermediate strains, "geometric" dynamic recrystallization leading to "pinching off" events of the original grains is observed, whereas at larger strains (ε > 5), grain fragmentation occurs by the generation of new grain boundaries ("continuous" dynamic recrystallization). The associated flow stress often exhibits pronounced softening and the resulting (equiaxed) grain size can be much smaller than the initial one. It is worth to note that a very similar sequence of mechanisms takes place in ferritic steels, as well as in aluminium alloys, in spite of their different crystallographic structure. In this paper, the above mechanisms will be illustrated by a set of data pertaining to titanium alloys.

Hall–Petch Relationship in Aluminum and Aluminum Alloys

2019 ◽  
Author(s):  
Ronald W. Armstrong
Keyword(s):  
Grain Size ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Pure Aluminum ◽  
Full Range ◽  
High Rate ◽  
Material Strength ◽  
Special Importance ◽  
Isentropic Compression ◽  
Face Centered

The mechanical properties of aluminum are shown to be of special importance beginning from the early 20th-century production of the material in single crystal and polycrystalline form. Experimental and theoretical researches of the time were concerned with particular influence of polycrystalline microstructure and the presence of crystal (grain) boundaries on both the material strength properties and on relation of those same properties to those for the full range of metal and alloy structures. Now it is well established that a relatively low value of the microstructural stress intensity, kε, is obtained for aluminum in the generalized Hall–Petch relation for its stress–strain, σε − ε, behavior depending on the average grain diameter, l, with intercept (friction) stress, σ0ε, which relation is given as: id="unequ63_1">σε=σ0ε+kεl−1/2With hindsight, taking σε = σ0ε provided the first connection between single crystal and polycrystalline strength measurements in the pioneering Taylor theory of plasticity proposed for aluminum and other face-centered cubic metals. Later, conventional and ultrafine grain size measurements are shown to verify the fuller H–P dependence. The present account builds onto the early history. A description is given for temperature, strain rate, and alloy-dependent mechanical property measurements. An understanding of the total measurements is described in terms of a dislocation pile-up model description for the relation. Emphasis is given to kε for pure aluminum and related metals being determined by cross-slip forced at grain boundaries. Particular attention is given to two characteristics of the metal mechanical behavior: (1) very high rate loading deformations leading to shock and shock-less isentropic compression experiments and (2) important grain size influences on nanopolycrystalline material behaviors. Additional results are presented on H–P aspects of the material strain ageing, shear banding, ductile fracturing, and fatigue behaviors.

Abundant grain boundaries activate highly efficient lithium ion transportation in high rate Li4Ti5O12 compact microspheres

2019 ◽  
Vol 7 (3) ◽  
pp. 1168-1176 ◽  
Author(s):  
Jiaming Ma ◽  
Yinping Wei ◽  
Lin Gan ◽  
Chao Wang ◽  
Heyi Xia ◽  
...  
Keyword(s):  
Energy Density ◽  
Grain Boundaries ◽  
Lithium Ion ◽  
High Rate ◽  
Highly Efficient ◽  
Tap Density ◽  
Ion Transportation ◽  
Huge Challenge

It is a huge challenge for high-tap-density electrodes to achieve high volumetric energy density but without compromising the ionic transportation.

Observation of a minimum reaction initiation threshold in ball-milled Ni+Al under high-rate mechanical loading

2011 ◽  
Vol 109 (6) ◽  
pp. 066108 ◽  
Author(s):  
Eric B. Herbold ◽  
Naresh N. Thadhani ◽  
Jennifer L. Jordan
Keyword(s):  
Mechanical Loading ◽  
High Rate ◽  
Reaction Initiation
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