scholarly journals Defects, Diffusion and Dopants in Sillimanite

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 857
Author(s):  
Raveena Sukumar ◽  
Poobalasuntharam Iyngaran ◽  
Navaratnarajah Kuganathan ◽  
Alexander Chroneos
Keyword(s):  
Pair Potential ◽  
Chemical Properties ◽  
Activation Energies ◽  
Aluminum Silicate ◽  
Intrinsic Defect ◽  
Ion Diffusion ◽  
Silicon Alloys ◽  
Aluminum Silicon Alloys ◽  
Cation Disorder ◽  
Industrial Preparation

Aluminum silicate based mineral “Sillimanite” (Al2SiO5) is important in the industrial preparation of aluminum-silicon alloys and cement. In the present study classical pair potential simulations are used to examine the intrinsic defect processes, diffusion pathways of Al3+ and O2− ions together with their activation energies and promising dopants on the Al and Si sites in Al2SiO5. The cation anti-site (Al-Si) defect cluster is calculated to be the most favorable defect, highlighting the cation disorder in this material, in agreement with the experiment. The cation disorder is important as this defect can change the mechanical and chemical properties of Al2SiO5. The Al3+ ions and O2− ions migrate in the c direction with corresponding activation energies of 2.26 eV and 2.75 eV inferring slow ion diffusion. The prominent isovalent dopants on the Al and Si sites are found to be the Ga and Ge, respectively, suggesting that they can be used to prevent phase transformation and tune the properties of sillimanite.

REYNOLDS 390 and A390

Alloy Digest ◽  
1971 ◽  
Vol 20 (8) ◽  
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
High Hardness ◽  
Heat Treating ◽  
Silicon Alloys ◽  
Aluminum Silicon Alloys ◽  
Temperature Performance

Abstract REYNOLDS 390 and A390 are hypereutectic aluminum-silicon alloys having excellent wear resistance coupled with good mechanical properties, high hardness, and low coefficients of expansion. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fatigue. It also includes information on high temperature performance and corrosion resistance as well as casting, heat treating, and machining. Filing Code: Al-203. Producer or source: Reynolds Metals Company.

ALUMINUM 713.0

Alloy Digest ◽  
1985 ◽  
Vol 34 (12) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Room Temperature ◽  
High Strength ◽  
Heat Treating ◽  
Good Combination ◽  
Casting Alloy ◽  
Silicon Alloys ◽  
Aluminum Silicon Alloys ◽  
Permanent Mold Castings ◽  
Aluminum Base

Abstract ALUMINUM 713.0 is an aluminum-base casting alloy that ages at room temperature to provide high-strength sand and permanent-mold castings. It has a good combination of mechanical properties and its corrosion resistance is equivalent to that of the aluminum-silicon alloys. It is dimensionally stable. Among its many uses are housings, machinery parts, fittings, lever arms and brackets. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and compressive and shear strength as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-263. Producer or source: Various aluminum companies.

The Effects of Microstructure on Properties

2004 ◽  
pp. 39-46
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Detailed Examination ◽  
Intermetallic Phases ◽  
Primary Phase ◽  
Silicon Alloys ◽  
Aluminum Silicon Alloys ◽  
Aluminum Castings ◽  
Eutectic Modification ◽  
Grain Size And Shape

Abstract In castings, microstructural features are products of metal chemistry and solidification conditions. The microstructural features, excluding defects, that most strongly affect the mechanical properties or aluminum castings are size, form, and distribution of intermetallic phases; dendrite arm spacing; grain size and shape; and eutectic modification and primary phase refinement. This chapter discusses the effects of these microstructural features on properties and methods for controlling them. The chapter concludes with a detailed examination of the refinement of hypereutectic aluminum-silicon alloys.

scholarly journals Defect, Diffusion and Dopant Properties of NaNiO2: Atomistic Simulation Study

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3094 ◽  
Author(s):  
Ruwani Kaushalya ◽  
Poobalasuntharam Iyngaran ◽  
Navaratnarajah Kuganathan ◽  
Alexander Chroneos
Keyword(s):  
Atomistic Simulation ◽  
High Capacity ◽  
Sodium Ion ◽  
Intrinsic Defect ◽  
Sodium Ion Batteries ◽  
Ion Diffusion ◽  
Defect Diffusion ◽  
Simulation Techniques ◽  
Defect Process ◽  
Isovalent Dopant

Sodium nickelate, NaNiO2, is a candidate cathode material for sodium ion batteries due to its high volumetric and gravimetric energy density. The use of atomistic simulation techniques allows the examination of the defect energetics, Na-ion diffusion and dopant properties within the crystal. Here, we show that the lowest energy intrinsic defect process is the Na-Ni anti-site. The Na Frenkel, which introduces Na vacancies in the lattice, is found to be the second most favourable defect process and this process is higher in energy only by 0.16 eV than the anti-site defect. Favourable Na-ion diffusion barrier of 0.67 eV in the ab plane indicates that the Na-ion diffusion in this material is relatively fast. Favourable divalent dopant on the Ni site is Co2+ that increases additional Na, leading to high capacity. The formation of Na vacancies can be facilitated by doping Ti4+ on the Ni site. The promising isovalent dopant on the Ni site is Ga3+.

scholarly journals Surface Characterization and Tribological Performance of Anodizing Micro-Textured Aluminum-Silicon Alloys

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1862 ◽  
Author(s):  
Luanxia Chen ◽  
Zhanqiang Liu ◽  
Bing Wang ◽  
Qinghua Song ◽  
Yi Wan ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Sliding Friction ◽  
Tribological Performance ◽  
Area Ratio ◽  
Micro Milling ◽  
Dry Sliding ◽  
Silicon Alloys ◽  
Aluminum Silicon Alloys ◽  
Aluminum Silicon

Eutectic aluminum-silicon alloys present high frictional coefficient and a high wear rate due to the low hardness under sliding friction conditions. In this paper, the eutectic aluminum-silicon alloy was textured firstly by micro-milling operations. Then, the micro-textured specimen was subjected to anodizing to fabricate alumina films. The surface topography, surface roughness, and bearing area ratio of micro-textured and anodizing micro-textured specimens were measured and characterized. For the anodizing micro-textured specimens, the surface roughness and superficial hardness increase compared with those for micro-textured ones. Tribological tests indicate that anodizing micro-textured samples present lower friction coefficient of 0.37 than that of flat samples of 0.43 under dry sliding conditions. However, they exhibit higher friction coefficient at 0.16 than that of flat samples of 0.13 under oil-lubricated conditions. The difference between the friction coefficient of anodizing micro-textured and flat samples under dry and oil-lubricated conditions is ascribed to the influence mechanism of surface roughness, bearing area ratio curves, and its relative parameters on the tribological performance of testing samples. The dry sliding friction coefficient has a positive correlation with bearing area ratio curves, while they present negative correlation with bearing area ratio curves under oil-lubricated conditions. The synergy method treated with micro-milling and anodizing provides an effective approach to enhance the dry sliding friction property of eutectic aluminum-silicon alloys.

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