Calculation of the product phase grain boundary area during solid state transformations

1988 ◽  
Vol 19 (9) ◽  
pp. 2123-2131 ◽  
Author(s):  
A. M. Gokhale
Keyword(s):  
Solid State ◽  
Grain Boundary ◽  
Product Phase ◽  
Boundary Area

scholarly journals Reduced Viscosity of Mg2GeO4 with Minor MgGeO3 between 1000 and 1150 °C Suggests Solid-State Lubrication at the Lithosphere–Asthenosphere Boundary

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 600
Author(s):  
Thomas Ferrand ◽  
Damien Deldicque
Keyword(s):  
Solid State ◽  
Grain Boundary ◽  
Metastable Phase ◽  
Viscosity Reduction ◽  
Tectonic Plates ◽  
Deformation Curves ◽  
Low Viscosity ◽  
Plasma Sintering ◽  
Stress Strain Relation ◽  
Spark Plasma

Tectonic plates are thought to move above the asthenosphere due to the presence of accumulated melts or volatiles that result in a low-viscosity layer, known as lithosphere–asthenosphere boundary (LAB). Here, we report experiments suggesting that the plates may slide through a solid-state mechanism. Ultrafine-grained aggregates of Mg2GeO4 and minor MgGeO3 were synthetized using spark plasma sintering (SPS) and deformed using a 1-atm deformation rig between 950 °C and 1250 °C. For 1000 < T < 1150 °C, the derivative of the stress–strain relation of the material drops down to zero once a critical stress as low as 30–100 MPa is reached. This viscosity reduction is followed by hardening. The deformation curves are consistent with what is commonly observed in steels during the shear-induced transformation from austenite to martensite, the final material being significantly harder. This is referred to as TRansformation-Induced Plasticity (TRIP), widely observed in metal alloys (TRIP alloys). It should be noted that such enhanced plasticity is not necessarily due to a phase transition, but could consist of any kind of transformation, including structural transformations. We suspect a stress-induced grain-boundary destabilization. This could be associated to the transient existence of a metastable phase forming in the vicinity of grain boundaries between 1000 and 1150 °C. However, no such phase can be observed in the recovered samples. Whatever its nature, the rheological transition seems to occur as a result of a competition between diffusional processes (i.e., thermally activated) and displacive processes (i.e., stress-induced and diffusionless). Consequently, the material would be harder at 1200 °C than at 1100 °C thanks to diffusion that would strengthen thermodynamically stable phases or grain-boundary structures. This alternative scenario for the LAB would not require volatiles. Instead, tectonic plates may slide on a layer in which the peridotite is constantly adjusting via a grain-boundary transformation.

Observation of Growth Front on the Initial Stage of Goss Abnormally-Growing Grain in Fe-3%Si Steel

2013 ◽  
Vol 753 ◽  
pp. 307-310
Author(s):  
Kyung Jun Ko ◽  
Jong Tae Park ◽  
Chan Hee Han
Keyword(s):  
Solid State ◽  
Grain Boundary ◽  
Three Dimensional ◽  
Secondary Recrystallization ◽  
Growth Front ◽  
Very High Frequency ◽  
Grain Boundary Mobility ◽  
Initial Stage ◽  
The Matrix

During abnormal grain growth, a few Goss grains grow exclusively fast and consume the matrix grains. The Goss abnormally-growing grain (AGG) has peculiar features which are irregular grain boundaries and very high frequency of peninsular grains nearby the growth front of AGG and island grains trapped inside AGG. These features might provide a clue for clarifying the mechanism of Goss AGG. The experimentally-observed microstructural feature and grain boundary characterization of Goss were approached by the solid-state wetting mechanism. In this study, observing the three-dimensional wetting morphology in serial section images of Goss AGG by EBSD, we report some direct microstrucrual evidence supporting solid-state wetting mechanism for Goss AGG. The solid-state wetting mechanism for the evolution of the Goss AGG in Fe-3%Si steel explains the microstructural features evolved during secondary recrystallization, which cannot be approached by the conventional theories based on the grain boundary mobility.

scholarly journals Synthesis of high-entropy alloy thin films via grain boundary diffusion–assisted solid-state alloying

2022 ◽  
Vol 207 ◽  
pp. 114302
Author(s):  
Seungjin Nam ◽  
Sang Jun Kim ◽  
Moon J. Kim ◽  
Manuel Quevedo-Lopez ◽  
Jun Yeon Hwang ◽  
...  
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Grain Boundary ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
High Entropy Alloy ◽  
High Entropy

Grain-boundary-resistance-less Na3SbS4-Se solid electrolytes for all-solid-state sodium batteries

Nano Energy ◽  
2019 ◽  
Vol 66 ◽  
pp. 104109 ◽  
Author(s):  
Hongli Wan ◽  
Jean Pierre Mwizerwa ◽  
Fudong Han ◽  
Wei Weng ◽  
Jing Yang ◽  
...  
Keyword(s):  
Solid State ◽  
Grain Boundary ◽  
Solid Electrolytes ◽  
Boundary Resistance ◽  
Sodium Batteries

The “Solidification” of Grain Boundaries with Increasing Temperature

1994 ◽  
Vol 357 ◽  
Author(s):  
Witold Lojkowski ◽  
Bogdan Palosz
Keyword(s):  
Solid State ◽  
Melting Point ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
High Temperatures ◽  
Low Temperatures ◽  
Melting Behavior ◽  
Wetting Transitions ◽  
Increasing Temperature ◽  
Segregation Of Impurities

AbstractThe aim of the paper is to explain the recently observed de-wetting grain boundary transition with increasing temperature. On the example of a bicrystal from the Fe-6at.%Si alloy, it was found recently that as temperature is increased, the following GB transitions take place: “solid” (or regular) GB-→“premelted” GB →“solid” GB. At the same time the wetting/de-wetting transitions have taken place. Another example of such GB behavior was discovered during sintering of alumina. The inverse melting behavior is explained as follows: low melting point impurities cause GB premelting at low temperatures, However de-segregation of impurities at high temperatures causes return of the GB structure to its regular “solid” state.

Monte-Carlo Simulation of Goss Abnormal Grain Growth in Fe-3%Si Steel by Sub-Boundary Enhanced Solid-State Wetting

2012 ◽  
Vol 715-716 ◽  
pp. 146-151
Author(s):  
K.J. Ko ◽  
A.D. Rollett ◽  
N.M. Hwang
Keyword(s):  
Monte Carlo ◽  
Solid State ◽  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Energy ◽  
Three Dimensional ◽  
Abnormal Grain Growth ◽  
Grain Boundary Energy ◽  
Simulation Based ◽  
Mc Simulation

The selective abnormal grain growth (AGG) of Goss grains in Fe-3%Si steel was investigated using a parallel Monte-Carlo (MC) simulation based on the new concept of sub-boundary enhanced solid-state wetting. Goss grains with low angle sub-boundaries will induce solid-state wetting against matrix grains with a moderate variation in grain boundary energy. Three-dimensional MC simulations of microstructure evolution with textures and grain boundary distributions matched to experimental data is using in this study.

Method of High Active Preparation and Electrical Properties of CuFeO2 Delafossite-Type

2014 ◽  
Vol 979 ◽  
pp. 302-306 ◽  
Author(s):  
Chalermpol Rudradawong ◽  
Aree Wichainchai ◽  
Aparporn Sakulkalavek ◽  
Yuttana Hongaromkid ◽  
Chesta Ruttanapun
Keyword(s):  
Crystal Structure ◽  
Electrical Conductivity ◽  
Solid State ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Solid State Reaction ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Metal Powders ◽  
High Power Factor

In this paper, the CuFeO2compound were prepared by classical solid state reaction (CSSR) and direct powder dissolved solution (DPDS) method from starting material metal oxides and metal powders. Preparation of two methods shows that, direct powder dissolved solution faster recover phases than classical solid state reaction method. The fastest method gets from starting materials Cu and Fe metal powders, the electrical conductivity, Seebeck coefficient, carrier concentration and mobility are 10.68 S/cm, 244.59 μV/K, 12.86×1016cm-3and 494.96 cm2/V.s, respectively. In addition, each CuFeO2compounds were investigated on crystal structure and electrical properties. From XRD and SEM results, all samples have a crystal structure delafossite-typeand a large grain boundary more than 15 μm by electrical conductivity corresponds to grain boundary and lattice parameter: a increases. Within this paper, from above results exhibit that preparation CuFeO2from Cu and Fe by direct powder dissolved solution method most appropriate for thermoelectric oxide materials due to high active for preparation else high lattice strain and high power factor are 0.00052 and 0.64×10-4W/mK2, respectively.

Rapid cycle-dependent softening of equal channel angularly pressed Sn–Ag–Cu alloy

2008 ◽  
Vol 23 (10) ◽  
pp. 2630-2638 ◽  
Author(s):  
Q.S. Zhu ◽  
Z.G. Wang ◽  
Q.L. Zeng ◽  
S.D. Wu ◽  
J.K. Shang
Keyword(s):  
Grain Boundary ◽  
Cast Alloy ◽  
Intermetallic Phase ◽  
Crack Density ◽  
Sharp Decrease ◽  
Surface Damage ◽  
Cyclic Stress ◽  
Grain Boundary Sliding ◽  
Cyclic Softening ◽  
Boundary Area

Cyclic stress–strain response of an equal channel angularly pressed Sn-3.8Ag-0.7Cu alloy was investigated to seek a mechanistic understanding of cyclic softening in Sn-rich alloys. The equal channel angular pressing (ECAP) was applied to modify the microstructure of the solder alloy by breaking up the needlelike Ag3Sn intermetallic phase into fine granules and by reducing the large β-Sn dendrites into smaller and equiaxed grains. The extruded alloys were subjected to strain-controlled fatigue test at various strain amplitudes. It was found that the extruded alloy exhibited a sharp decrease of the stress amplitude within the initial few cycles compared with the as-cast alloy. After only a few cycles, the alloy suffered from noticeable surface damage. In situ scanning electron microscopy observations of the cyclic bending specimens revealed an approximately logarithmic relationship between crack density and the number of cycles. A theoretical model of microcrack accumulation was constructed to explain the rapid cyclic softening behavior. The predicted results, based on the model, agreed well with the experimental data and indicated that the rapid softening had resulted from an increased tendency for grain boundary cracking in the ECAPed microstructure due to the increase in the grain boundary area per unit volume and the reduced resistance of Ag3Sn to grain boundary sliding.

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