Solid phase diffusion of tungsten in alloys during liquid phase sintering

1995 ◽  
Vol 50 (5) ◽  
pp. 48
Keyword(s):  
Liquid Phase ◽  
Solid Phase ◽  
Liquid Phase Sintering ◽  
Phase Diffusion

scholarly journals A mathematical approach to Ostwald ripening due to diffusion and deformation in liquid bridge

2013 ◽  
Vol 45 (3) ◽  
pp. 261-271 ◽  
Author(s):  
B. Randjelovic ◽  
K. Shinagawa ◽  
Z.S. Nikolic
Keyword(s):  
Liquid Phase ◽  
Liquid Bridge ◽  
Ostwald Ripening ◽  
Solid Phase ◽  
Liquid Phase Sintering ◽  
Solute Diffusion ◽  
Deformation Analysis ◽  
Mathematical Approach ◽  
Fe Method ◽  
Grain Coarsening

From many experiments with mixtures of small and large grains, it can be concluded that during liquid phase sintering, smaller grains partially dissolve and a solid phase precipitates on the larger grains and grain coarsening occurs. The growth rate can be controlled either by the solid-liquid phase boundary reaction or by diffusion through the liquid phase. The microstructure may change either by larger grains growing during the Ostwald ripening process or by shape accommodation. In this study, two-dimensional mathematical approach for simulation of grain coarsening by grain boundary migration based on a physical and corresponding numerical modeling of liquid phase sintering will be considered. A combined mathematical method of analyzing viscous deformation and solute diffusion in liquid bridge between two grains with different sizes will be proposed. The viscous FE method will be used for calculating meniscus of the liquid bridge, with the interfacial tensions taken into consideration. The FE method for diffusion will be also implemented by using the same mesh as the deformation analysis.

Interaction of Components of Co-Sn and Co-Sn-Cu Powder Materials in Liquid Phase Sintering

2019 ◽  
Vol 943 ◽  
pp. 113-118
Author(s):  
Evgeniy Georgiyevich Sokolov ◽  
Alexander Vitalyevich Ozolin ◽  
Lev Ivanovich Svistun ◽  
Svetlana Alexandrovna Arefieva
Keyword(s):  
Liquid Phase ◽  
Solid Phase ◽  
Steel Substrate ◽  
Liquid Phase Sintering ◽  
Powder Materials ◽  
Cu Alloys ◽  
Initial Stage ◽  
Interaction Of Components ◽  
Sintered Alloys ◽  
Liquid Tin

The interaction of components and structure formation were studied in liquid phase sintering of Co-Sn and Co-Sn-Cu powder materials. The powders of commercially pure metals were mixed with an organic binder and applied on the steel substrate. Sintering was performed under vacuum at temperatures of 820 and 1100 °C. The structure of sintered alloys was investigated by X-ray diffractometry and electron probe microanalysis, and microhardness (HV0.01) of the structural components was measured. It has been found that the nature of interaction of the liquid tin with the solid phase at the initial stage of sintering affects the formation of structure and porosity of Co-Sn and Co-Sn-Cu alloys considerably. In Co-Sn alloys, diffusion of tin into cobalt particles leads to the formation of intermetallic compounds, which hinders spreading of the liquid phase. This results in a porous defect structure formed in Co-Sn alloys. In Co-Sn-Cu alloys, at the initial stage of sintering the liquid phase enriched with copper is formed that wets the cobalt particles and contributes to their regrouping. As a result of this, materials with minor porosity are formed.

Microstructure and Properties of In Situ Fabricated Al-5wt.%Si-Al2O3 Composites

2012 ◽  
Vol 567 ◽  
pp. 15-20 ◽  
Author(s):  
Ling Cheng ◽  
De Gui Zhu ◽  
Ying Gao ◽  
Wei Li ◽  
Bo Wang
Keyword(s):  
Shear Strength ◽  
Liquid Phase ◽  
Solid Phase ◽  
Hold Time ◽  
Aluminum Matrix ◽  
Liquid Phase Sintering ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
X Ray

Alumina reinforced aluminum matrix composites (Al-5wt.%Si-Al2O3) fabricated by powder metallurgy through hot isotactic pressing were sintered in different processes, i.e. solid and liquid phase sintering. Optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive X-ray (EDX) techniques were used to characterize the sintered composites. The effects of solid phase and liquid phase sintering on density, microstructure, microhardness, compression and shear strength were investigated. It was found that in situ chemical reaction was completed in solid phase sintering, but the composites had lower microhardness, comprehension and shear strength due to low density and segregation of alumina and Si particles in microstructure. Segregation of reinforcement particles in solid phase sintering resulted from character of solid reaction and Si diffusion at high temperature over a long hold time.

scholarly journals Computer simulation of free settling and skeletal settling during liquid phase sintering

2006 ◽  
Vol 38 (1) ◽  
pp. 41-54 ◽  
Author(s):  
Z.S. Nikolic
Keyword(s):  
Computer Simulation ◽  
Liquid Phase ◽  
Solid Phase ◽  
Boundary Migration ◽  
Domain Boundary ◽  
Numerical Procedure ◽  
Simulation Models ◽  
Liquid Phase Sintering ◽  
Solid Skeleton ◽  
Two Stages

In recent years, a range of computer simulation models leading to a better understanding of liquid phase sintering phenomena, have been developed with the aim of simulating the detailed evolution of microstructure during grain growth. Some liquid phase sintered materials show both macrostructural and microstructural effects associated with gravity force. Therefore we will develop a numerical procedure for the estimation of how much gravity will influence domain (two-dimensional particle representation) growth, domain boundary migration and solid skeleton formation due to gravity induced segregation during liquid phase sintering. The method used for the simulation of a gravity field will be based on the settling procedure. Gravity induced settling will be separated into two stages - Free Settling and Skeletal Settling. Isolated solid phase domains fall under gravity and slide down over the already settled domains (free settling). During settling they make point contacts with each other. Necks between them then form and start to grow until the equilibrium dihedral angle between the domain boundaries and the liquid is established. Thus a solid skeleton forms and skeletal settling of a connected solid structure takes place. .

scholarly journals Silicon carbide liquid-phase sintering with various activating agents

2018 ◽  
pp. 24-30
Author(s):  
S. N. Perevislov ◽  
M. V. Tomkovich ◽  
A. S. Lysenkov
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Liquid Phase ◽  
Mechanical Characteristics ◽  
Solid Phase ◽  
Physical And Mechanical Properties ◽  
Liquid Phase Sintering ◽  
Sintered Materials

The liquid-phase sintering at 1860‒2100 °C was used to prepare the silicon-carbide materials with the 5‒10 weigh percent of oxide additions. The SiC material with the 20 weigh percent of three-component MgO‒Y2O3‒Al2O3system addition showed the ultimate physical and mechanical properties. The mechanical characteristics of the liquidphase sintered materials with the 15 weigh percent of the three-component oxides addition exceed those of both the reactive-sintered and the solid-phase sintered materials and approach to those of the hot-pressed materials.Ill. 5. Ref. 31. Tab. 2.

Mechanical properties of Al-Cu/B4C and Al-Mg/B4C metal matrix composites

2021 ◽  
Vol 63 (4) ◽  
pp. 350-355
Author(s):  
Mehmet Ayvaz ◽  
Hakan Cetinel
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Liquid Phase ◽  
Oxide Layer ◽  
Solid Phase ◽  
Aluminum Matrix ◽  
Liquid Phase Sintering ◽  
Aluminum Matrix Composites ◽  
Powder Metallurgy Method ◽  
Matrix Composites

Abstract To be able to successfully produce ceramic-reinforced aluminum matrix composites by using the powder metallurgy method, the wetting of ceramic reinforcements should be increased. In addition, the negative effects of the oxide layer of the aluminum matrix on sinterability should be minimized. In order to break the oxide layer, the deoxidation property of Mg can be used. Furthermore, by creating a liquid phase, both wettability and sinterability can be improved. In this study, the effects of Mg and Cu alloy elements and sintering phase on the wettability, sinterability, and mechanical properties of Al/B4C composites were investigated. For this purpose, various amounts (5, 10, 20, and 30 wt.-%) of B4C reinforced Al5Cu and Al5Mg matrix composites were produced by the powder metallurgy method. After pressing under 400 MPa pressure, composite samples were sintered for 4 hours. The sintering was carried out in two different groups as solid phase sintering at 560 °C and liquid phase sintering at 610 °C. Despite the deoxidation effect of Mg in Al5Mg matrix composites, higher mechanical properties were determined in Al5Cu composites which were sintered in liquid phase because wettability increased. The highest mechanical properties were obtained in the 20 wt.-% B4C reinforced Al5Cu sample sintered in liquid phase.

SEM Investigation of the Structure of Ceramic Matrix Composite Produced from Iron-Ore Waste

2013 ◽  
Vol 831 ◽  
pp. 36-39
Author(s):  
А.U. Stolboushkin ◽  
V.N. Zorya ◽  
О.А. Stolboushkina
Keyword(s):  
Liquid Phase ◽  
Matrix Composite ◽  
Iron Ore ◽  
Solid Phase ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix ◽  
Liquid Phase Sintering ◽  
New Mineral ◽  
Mineral Phases ◽  
The Matrix

The article gives the results of scanning electron microscopy (SEM) studies of the structure of ceramic matrix composite materials produced from iron ore waste. It is established that inside the matrix and the granules during the firing the processes of solid-phase and liquid-phase sintering with formation of new mineral phases take place. It is shown that in the matrix a liquid phase is formed, which fills intergranular cells and binds the particles of minerals together.

scholarly journals Excess Li2O Additives to Promote Grain Boundary Growth and Improve Ionic Conductivity of LiTa2PO8 Solid Electrolytes

2021 ◽  
Vol 8 ◽  
Author(s):  
Qian Zhang ◽  
Fuhai Meng ◽  
Ruixiong Liao ◽  
Long Chen ◽  
Mengqian Xu ◽  
...  
Keyword(s):  
Solid State ◽  
Liquid Phase ◽  
Ionic Conductivity ◽  
Grain Boundary ◽  
Solid Phase ◽  
Synthesis Method ◽  
Lithium Ion ◽  
Liquid Phase Sintering ◽  
Diffusion Activation Energy ◽  
The Impact

LiTa2PO8 (LTPO) is a new solid-state lithium ion electrolyte material reported in the latest research, which has high bulk ionic conductivity and low grain boundary ion conductivity. However, it is difficult to density with conventional sintering methods. Herein, in this work, the solid-phase synthesis method was used to prepared the LTPO solid-state electrolyte, and the influence of the amount of lithium on the structure and performance of LTPO electrolyte material was investigated. The results show that the excess Li2O does not increase other impurities and does not change the structure of the material, but the liquid phase produced by the excess Li2O can promote the elimination of interfacial pores, accelerate the direct bonding of grains and improve the ionic conductivity of grain boundary, thus improving the overall ionic conductivity of the material. Considering the volatilization of lithium and the impact of liquid phase sintering at high temperatures and the content restructuring, after adding 20 wt% excess formulation of Li2O, the resultant of LTPO density is 5.0 g/cm3, the density reaches 85.58%. As a result, the total ionic conductivity of the electrolyte is 3.28 × 10–4 S/cm at 25°C, and the Li-ion diffusion activation energy is 0.27 eV. In addition, after loading this electrolyte into a Li–Li symmetric battery, it is proved that the electrolyte has lithium ion transport performance and can be used in all-solid-state batteries. However, it is also found from cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) analysis that the interface between LTPO material and Li is unstable, and Ta5+ ions are reduced, which will be another key issue to be addressed in the future.

Computer Study of Skeletal Settling Combined with Extrication of Solid Phase Domains during Liquid Phase Sintering of Tungsten Heavy Alloy

2007 ◽  
Vol 352 ◽  
pp. 9-12 ◽  
Author(s):  
Zoran S. Nikolic ◽  
Masahiro Yoshimura
Keyword(s):  
Liquid Phase ◽  
Solid Phase ◽  
Center Of Mass ◽  
Liquid Phase Sintering ◽  
Domain Model ◽  
Tungsten Heavy Alloy ◽  
Computer Study ◽  
Porous Microstructure ◽  
Definition Of ◽  
Dissolution And Precipitation

In this paper, we investigated numerically gravity induced skeletal settling during liquid phase sintering. The microstructural evolution will be simulated by simultaneous computation of displacement of the center of mass and mass transport due to dissolution and precipitation at the interfaces between solid-phase and liquid matrix. Common to this study based on domain methodology for definition of regular multi-domain model will be the need to relate some diffusional phenomena to essential geometric and topological attributes of the W-Ni porous microstructure influenced by skeletal settling combined with extrication of some solid-phase domains during liquid phase sintering.

scholarly journals Mechanism of Ion-Diffusion Solid-Phase Reduction of Iron Oxides of Technogenic Origin in the Presence of the Liquid Phase and without it

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1564
Author(s):  
Oleg Sheshukov ◽  
Mikhail Mikheenkov ◽  
Larisa Vedmid’ ◽  
Iliya Nekrasov ◽  
Denis Egiazaryan
Keyword(s):  
Liquid Phase ◽  
Iron Oxides ◽  
Catalytic Mechanism ◽  
Solid Phase ◽  
Pressing Pressure ◽  
Iron Ions ◽  
Ion Diffusion ◽  
Kinetic Dependence ◽  
Phase Diffusion ◽  
Reduction Of Iron

The processes of iron oxides’ reduction have a complex physicochemical mechanism, with the participation of solid, liquid, and gaseous substances. The article discusses the existing models for the reduction of iron oxides and provides data on the thermodynamic possibility of carrying out the reactions of their reduction through the solid and gas phases. Experimental data on the reduction of iron from industrial scale, obtained by the DSC (differential scanning calorimetry) method, show the kinetic dependence of the rate and completeness of recovery on external factors: pressing pressure during sample preparation and the reagents’ composition. The pressing pressure, under conditions of iron ions’ solid-phase diffusion, has the significant effect by increasing the reagents’ contact area. Under conditions of iron ions’ comprehensive diffusion, the pressing pressure does not affect the reduction processes rate. The introduction of 10 mass.% flux into the raw mixture composition leads to a partially liquid-phase diffusion of iron ions and weakens the effect of the pressing pressure in this process. An ion diffusion-catalytic mechanism is proposed to describe the observed effects during the reduction of iron oxide of technogenic origin.

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