Influence of Dysprosium Compounds on the Extraction Behavior of Dy from Nd-Dy-Fe-B Magnet Using Liquid Magnesium

During the liquid metal extraction reaction between a Nd-Dy-Fe-B magnet and liquid Mg, Nd rapidly diffuses out of the magnet, whereas Dy is not extracted due to the reaction with the matrix and the formation of Dy2Fe17 phase. In addition, theDy2O3 phase exists at the grain boundaries. Until now, only the effect of the Dy2O3 phase on the extraction of Dy has been reported. In this study, the effect of the Dy2Fe17 phase on the extraction of Dy from the Nd-Dy-Fe-B magnet was investigated in liquid Mg. The formation of the Dy2Fe17 phase during the reaction between Mg and matrix (RE2Fe14B) was first examined using a thermodynamical approach and confirmed by microstructural analysis. It was observed that Dy extraction was dominated by Dy2Fe17 phase decomposition from 3 h to 24 h, followed by Dy2O3 phase dominant reaction with Mg. Comparing the activities of the Dy2Fe17 phase and the Dy2O3 phase, the reaction of Dy2Fe17 is dominant, as compared to the Dy2O3 phase. Finally, at 48 h, the high Dy extraction percentage of 93% was achieved. As a result, in was concluded that the Dy2Fe17 phase acts as an obstacle in the extraction of Dy. In the future, if research to control the Dy2Fe17 phase proceeds, it will be of great importance to advance the recycling of Dy.

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Electrolytic Isolation of Twin-Type Shock Deformation Structures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100061604 ◽

1967 ◽

Vol 25 ◽

pp. 318-319

Author(s):

F. I. Grace ◽

L. E. Murr

Keyword(s):

Grain Boundaries ◽

Thin Foil ◽

Electrolyte Composition ◽

Experimental Conditions ◽

Average Current Density ◽

Electron Transmission ◽

Deformation Structures ◽

The Matrix ◽

Average Current ◽

Specimen Edge

During the course of electron transmission investigations of the deformation structures associated with shock-loaded thin foil specimens of 70/30 brass, it was observed that in a number of instances preferential etching occurred along grain boundaries; and that the degree of etching appeared to depend upon the various experimental conditions prevailing during electropolishing. These included the electrolyte composition, the average current density, and the temperature in the vicinity of the specimen. In the specific case of 70/30 brass shock-loaded at pressures in the range 200-400 kilobars, the predominant mode of deformation was observed to be twin-type faults which in several cases exhibited preferential etching similar to that observed along grain boundaries. A novel feature of this particular phenomenon was that in certain cases, especially for twins located in the vicinity of the specimen edge, the etching or preferential electropolishing literally isolated these structures from the matrix.

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Diffraction effects from inclined grain boundaries in polycrystalline thin foils

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109240 ◽

1978 ◽

Vol 36 (1) ◽

pp. 420-421

Author(s):

C.B. Carter ◽

A.M. Donald ◽

S.L. Sass

Keyword(s):

Thin Film ◽

Grain Boundaries ◽

Boundary Plane ◽

Foil Surface ◽

Thin Foils ◽

The Matrix ◽

Firm Basis ◽

Diffraction Patterns ◽

Wave Matching ◽

Diffraction Effects

Using thin-film gold bicrystals with the boundary plane parallel to the foil surface, it has been shown(l,2) that networks of grain boundary dislocations can act as diffraction gratings and give rise to subsidiary reflections close to the matrix reflections in electron diffraction patterns. Recently several groups of workers(3-5) have shown that inclined boundaries in polycrystalline specimens also produce extra reflections which may be due to the periodic nature of the boundaries. In general grain boundaries in polycrystalline specimens will be steeply inclined to the foil surface and additional reflections due to wave matching at the boundary(6) will also be present. The diffraction technique has the potential for providing detailed information on the structure of inclined boundaries (see, for example (5)), especially for the case where the image contains no useful information. In order to provide a firm basis for this technique, the geometry of the diffraction effects expected from inclined boundaries and the influence of these effects on the appearance of images will be examined.

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Lattice imaging of precipitates in Al-Zn-Mg alloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143651 ◽

1986 ◽

Vol 44 ◽

pp. 412-413

Author(s):

C. K. Wu

Keyword(s):

Grain Boundaries ◽

Homogeneous Nucleation ◽

Alloy System ◽

Mg Alloy ◽

List Type ◽

Lattice Structures ◽

Type Number ◽

Orientation Relationships ◽

Lattice Imaging ◽

The Matrix

The precipitation phenomenon in Al-Zn-Mg alloy is quite interesting and complicated and can be described in the following categories:(i) heterogeneous nucleation at grain boundaries;(ii) precipitate-free-zones (PFZ) adjacent to the grain boundaries;(iii) homogeneous nucleation of snherical G.P. zones, n' and n phases inside the grains. The spherical G.P. zones are coherent with the matrix, whereas the n' and n phases are incoherent. It is noticed that n' and n phases exhibit plate-like morpholoay with several orientation relationship with the matrix. The high resolution lattice imaging techninue of TEM is then applied to study precipitates in this alloy system. It reveals the characteristics of lattice structures of each phase and the orientation relationships with the matrix.

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MICROSTRUCTURAL EVOLUTION OF Al-Cu-Mg-Ag ALLOY WITH TRACE Zr ADDITION DURING TWO-STEP HOMOGENIZATION

International Journal of Modern Physics B ◽

10.1142/s0217979209060142 ◽

2009 ◽

Vol 23 (06n07) ◽

pp. 855-862 ◽

Cited By ~ 3

Author(s):

FEIYUE MA ◽

ZHIYI LIU

Keyword(s):

Melting Point ◽

Grain Boundaries ◽

Microstructural Evolution ◽

Cast Alloy ◽

Scanning Calorimetry ◽

Zr Addition ◽

Homogenization Time ◽

The Matrix ◽

Higher Temperature ◽

Lower Temperature

The microstructural evolution in an Al - Cu - Mg - Ag alloy with trace Zr addition during homogenization treatment was characterized by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray Spectroscopy (EDS). It was shown that the low-melting-point phase segregating toward grain boundaries is Al 2 Cu , with a melting point of 523.52°C. A two-step homogenization process was employed to optimize the microstructure of the as-cast alloy, during which the alloy was first homogenized at a lower temperature, then at a higher temperature. After homogenized at 420°C for 6 h, Al 3 Zr particles were finely formed in the matrix. After that, when the alloy was homogenized at an elevated temperature for a longer time, i.e., 515°C for 24 h, most of the precipates at the grain boundaries were removed. Furthermore, the dispersive Al 3 Zr precipitates were retained, without coarsening greatly in the final homogenization step. A kinetics model is employed to predict the optimal homogenization time at a given temperature theoretically, and it confirms the result in present study, which is 420°C/6h+515°C/24h.

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Microstructure of Polycrystalline MgO Penetrated by a Silicate Liquid

Microscopy and Microanalysis ◽

10.1017/s1431927696211134 ◽

1996 ◽

Vol 2 (3) ◽

pp. 113-128 ◽

Cited By ~ 3

Author(s):

Sundar Ramamurthy ◽

Michael P. Mallamaci ◽

Catherine M. Zimmerman ◽

C. Barry Carter ◽

Peter R. Duncombe ◽

...

Keyword(s):

Grain Boundaries ◽

Grain Growth ◽

Glassy Phase ◽

Silicate Liquid ◽

Two Phase ◽

The Matrix ◽

Devitrification Process ◽

Phase Mixture

Dense, polycrystalline MgO was infiltrated with monticellite (CaMgSiO4) liquid to study the penetration of liquid along the grain boundaries of MgO. Grain growth was found to be restricted with increasing amounts of liquid. The inter-granular regions were generally found to be comprised of a two-phase mixture: crystalline monticellite and a glassy phase rich in the impurities present in the starting MgO material. MgO grains act as seeding agents for the crystallization of monticellite. The location and composition of the glassy phase with respect to the MgO grains emphasizes the role of intergranular liquid during the devitrification process in “snowplowing” impurities present in the matrix.

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Microstructural Analysis and Wear Behavior of Cryogenically Treated Ti-6Al-4V Alloy

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.592-594.1331 ◽

2014 ◽

Vol 592-594 ◽

pp. 1331-1335 ◽

Cited By ~ 1

Author(s):

Haider Nasreen ◽

S. Beer Mohamed ◽

S. Rasool Mohideen

Keyword(s):

Grain Boundaries ◽

Wear Behavior ◽

Cryogenic Treatment ◽

Microstructural Analysis ◽

Wear Loss ◽

Β Phase ◽

Α Phase ◽

Treated Sample

This paper helps in understanding the effects of cryogenic treatment on microstructural variation, hardness and wear behavior of Ti-6Al-4V alloy. The microstructure indicates white β-phase dispersed on the grain boundaries of dark α-phase. Cryogenic treatment at-186 °C for 10 h led to the transformation from β-phase to α-phase, resulting in coarsening of α. Hardness of the cryogenically treated sample was observed to decrease and wear loss was observed to increase; this can be attributed to the coarsening of α-phase.

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Process optimization for enhanced tribological properties of Al/MWCNT composites produced by powder metallurgy using artificial neural networks

Surface Topography Metrology and Properties ◽

10.1088/2051-672x/ac3a53 ◽

2021 ◽

Author(s):

Turker Turkoglu ◽

Sare Celik

Keyword(s):

Powder Mixture ◽

Pure Aluminum ◽

Microstructural Analysis ◽

Wear Test ◽

Structural Defects ◽

Wear Loss ◽

Ann Model ◽

Wear Properties ◽

The Matrix ◽

Artificial Neural

Abstract In order to eliminate the agglomeration problem of reinforcement in the nanocomposite, a two-step dispersion process was employed. Under ultra-sonication and ball milling, 1 wt.% of multi-walled carbon nanotubes (MWCNTs) were properly dispersed in pure aluminum (Al) (used as the matrix phase). The composite powder mixture was then consolidated in an inert Ar gas atmosphere by hot pressing under certain fabrication parameters. The powder mixture was characterized by Raman Spectroscopy, and it was found that MWCNTs did not cause structural defects in the pre-production process. The microstructural analysis of the sintered composites by scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopy (EDS), revealed that the reinforcement was uniformly distributed in the matrix. Wear test results indicated that the wear resistance of the composites increased with increase of MWCNT reinforcement, and the wear mechanism was determined to be a mixing type by examining the wear traces by SEM. In order to determine the effects of different process parameters on wear loss, a multilayer perceptron (MLP) based artificial neural network (ANN) was used, and experimental and predicted values were compared. It was noticed that the MLP based ANN model effectively evaluated the wear properties of the Al/MWCNT composites.

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Microstructural analysis of Al6063/sic with calcium additives for hardness enhancement

MATEC Web of Conferences ◽

10.1051/matecconf/201822503007 ◽

2018 ◽

Vol 225 ◽

pp. 03007

Author(s):

Balaji Bakthavatchalam ◽

Khairul Habib ◽

Namdev Patil ◽

Omar A Hussein

Keyword(s):

Mechanical Properties ◽

Silicon Carbide ◽

Matrix Material ◽

Microstructural Analysis ◽

Wear Loss ◽

Alloying Element ◽

Silicon Phase ◽

High Durability ◽

The Matrix ◽

Al6063 Alloy

Microstructural Analysis plays an important role in enhancing the mechanical properties of metals and composites. Usually Aluminium Silicon Carbide (Al6063/SiC) alloys are mixed with strontium, sodium and antimony for high durability even though they are toxic and costly. As an alternative calcium is used as an alloying element to improve the mechanical property of Al6063/Sic alloy. In this paper Al6063 is chosen as the matrix material while Sic is used as a reinforcement where calcium powder is added to modify the silicon phase of the composite. Finally, concentration of Silicon carbide is varied from 0 to 150 mg to produce four specimens of Al6063 alloy and it is subjected to microstructure analysis which showed the reduction of grain size and therefore improvement in the hardness from 52.9 HV to 58.4 HV and decrease in the wear loss from 3.97 to 3.27 percentage.

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Study on the Evolution of the γ′ Phase and Grain Boundaries in Nickel-Based Superalloy during Interrupted Continuous Cooling

Crystals ◽

10.3390/cryst11121464 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1464

Author(s):

Haiping Wang ◽

Dong Liu ◽

Jianguo Wang ◽

Yanhui Yang ◽

Haodong Rao ◽

...

Keyword(s):

Grain Boundaries ◽

Short Distance ◽

Creep Property ◽

Maximum Amplitude ◽

Matrix Diffusion ◽

Cooling Rates ◽

Continuous Cooling ◽

Nickel Based Superalloy ◽

The Matrix ◽

Solute Atoms

The formation of the irregular γ′ precipitates in the nickel-based superalloy Waspaloy was investigated during the continuous cooling, which is relevant to the cooling rates and interrupted temperature. The morphology of the γ′ precipitates was observed to change from a dispersed sphere to the flower-like one with the decreasing of the cooling rates. It was found that there are three modes of transportation of the solute atoms involved in relation to the γ′ precipitates: dissolution from the small γ′ precipitates to the γ matrix, diffusion to the large γ′ precipitates from the matrix, and the short distance among γ′ precipitates close to each other. Meanwhile, the slower cooling rates tend to result in the serrated grain boundaries, and the wavelength between successive peaks (λ) and the maximum amplitude (A) are larger with the decreasing of the cooling rates. The content of the low ΣCSL boundaries increases with the decreasing of the cooling rates, which is of great benefit in improving the creep property of the Waspaloy.

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Mirror fault formation and coseismic slip at surface conditions: an example of faulting in unconsolidated deposits in the Central Apennines (Italy)

10.5194/egusphere-egu21-5846 ◽

2021 ◽

Author(s):

Matteo Demurtas ◽

Oliver Plümper ◽

Markus Ohl ◽

Fabrizio Balsamo ◽

Mattia Pizzati

Keyword(s):

Grain Boundaries ◽

Amorphous Material ◽

Hanging Wall ◽

Microstructural Analysis ◽

Central Apennines ◽

Near Surface ◽

Fault Surface ◽

Mechanics Of Faulting ◽

Seismic Rupture ◽

Late Pleistocene To Holocene

Faulting in seismically active regions commonly involves the deformation of unconsolidated to poorly lithified sediments at shallow to near-surface depths. When compared to classic crustal strength profiles that predict a velocity-strengthening behaviour for the first few km of depth, the propagation of seismic rupture to the surface appears counterintuitive. Rock deformation experiments have shown an inverse relationship between normal stress and displacement needed to the onset of dynamic weakening during seismic slip, meaning that for a seismic rupture to be able to propagate towards the surface, displacements should be large enough to counter the progressive decrease of normal and confining stresses.In this contribution, we document the occurrence of mirror-like faults that formed within 20-30 m-thick, unconsolidated colluvium fan deposits at the hanging wall of the active Vado di Corno Fault Zone (VCFZ) in the Central Apennines, Italy. The deposits lie in direct contact with the master normal-fault surface, are Late Pleistocene to Holocene in age, and consist of angular carbonate clasts with grain size ranging ~0.1-10 mm derived from the dismantling of the adjacent VCFZ footwall. Field observations of cross cutting relationships and marker layer displacements suggest a maximum formation depth of the faults of c. 20-30 m and slip accommodated along single faults on the order of few cm. Faults are organised in three sets: subvertical, N-S and NE-SW trending faults, and WNW-ESE striking faults, synthetic and antithetic to the VCFZ master fault surface (N195/55&#176;). Faults are commonly lineated with a dip-slip to slightly oblique kinematic.Detailed microstructural analysis of the mirror faults shows extreme strain localization on a 2-5 &#181;m thick principal slip zone composed of calcite nanograins ranging 10s-100s nm in size with amorphous material and phyllosilicates occurring along grain boundaries and within intragranular porosity. Locally, aggregates of nanograins coalesce and transition to &#181;m-sized polygonal, larger grains. Calcite nanograins are mostly equant, with straight grain boundaries, 120&#176; dihedral angles, and negligible porosity. These microstructures strongly resemble high temperature recrystallization structures documented along seismic faults exhumed from >5 km of depth, where stresses are significantly larger. In our case, field constraints show that deformation occurred in very confining stress conditions and with limited displacement.Collectively, our observations provide new documentation on the conditions for the formation of mirror faults and new insights into the mechanics of faulting and strain accommodation in the shallowest part of the crust (< 1 km).

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