Structure formation of alloys of tin — zinc system during high-rapid solidification

2021 ◽  
Vol 2 ◽  
Author(s):  
V. G. Shepelevich ◽  
◽  
D. A. Zernitsa ◽  
Keyword(s):  
Solid Solution ◽  
Specific Surface ◽  
Zinc Concentration ◽  
Volume Fraction ◽  
Liquid Solution ◽  
Unstable State ◽  
Microcrystalline Structure ◽  
Small Particles ◽  
Large Particles ◽  
Rapidly Solidified

The results of a study of the structure parameters of rapidly solidified foil of a hypoeutectic, eutectic, hypereutectic Sn—Zn system alloys containing 4.4; 8.8 and 15 mas. % Zn are presented Rapidly solidified foil consists of equiaxed zinc particles and a supersaturated tin solid solution. Zinc particles are distributed uniformly in the foil, that is caused by the formation of a supercooled and supersaturated liquid solution and its subsequent spinodal decomposition. The areas of the liquid solution enriched with tin and zinc are transformed into nuclei of crystalline phases. With an increase in the zinc concentration in the studied alloys, the volume fraction of zinc particles, the average chord of random secant sections at the sections of zinc particles, and the specific surface of the interphase formed by zinc and tin increase. The foil of Sn—Zn alloys has a microcrystalline structure in which the predominant grain orientation is observed. The formation of the texture of (100) tin and (0001) zinc occurs. Rapidly solidified alloy foils are in an unstable state, that results in the decomposition of a tin solid solution, the dissolution of small particles and the growth of large particles. Annealing at 180 °C for 22 hours causes an increase in the average chord of sections of zinc particles, volume of zinc particles and a decrease in the specific surface of the interface.

scholarly journals The structure of rapidly solidified foil of the eutectic Sn – 8.8 wt. % Zn alloy

2020 ◽  
pp. 67-72
Author(s):  
Vasili G. Shepelevich ◽  
Denis A. Zernitsa
Keyword(s):  
Solid Solution ◽  
Specific Surface ◽  
Solid Solutions ◽  
Eutectic Alloy ◽  
Volume Fraction ◽  
Average Particle Size ◽  
Unstable State ◽  
Average Particle ◽  
Alloy Foil ◽  
Rapidly Solidified

Microstructure of rapidly solidified eutectic alloy foil Sn – 8.8 wt. % Zn was studied. The alloy foil consists of solid solutions of zinc and tin. Dark equiaxed dispersed precipitates of zinc solid solution are uniformly interspersed in the matrix of tin solid solution. The parameters of the microstructure were determined. The average chord of a random secant at the sections of precipitates of a solid solution of zinc is 0.33 mm, and the specific interface surface is 0.81 mm–1. The precipitations of the tin solid solution have a microcrystalline structure. Specific surface of high angle boundaries less than 1 mm–1. The texture of the precipitates of solid solutions of tin and zinc in the foil was studied, and the pole densities of the diffraction lines of these phases are presented. The tin solid solution has the texture (100), and the zinc solid solution has the (0001) texture, which is explained by the predominant growth of grains, in which the crystalline planes of (100) tin and (0001) zinc are most closely packed and perpendicular to the heat flux. Eutectic alloy Sn – 8.8 wt. % Zn is in an unstable state. Annealing the foil causes the dissolution of small and coarsening of large particles of zinc solid solution, as well as the decomposition of a supersaturated tin solid solution. These processes cause an enlargement of the microstructure: an increase in the average particle size (dZn) of a solid solution of zinc and its volume fraction (VZn), a decrease in the specific surface (S ) of interphase boundaries.

scholarly journals Turbulent channel flow of a dense binary mixture of rigid particles

2017 ◽  
Vol 818 ◽  
pp. 623-645 ◽  
Author(s):  
Iman Lashgari ◽  
Francesco Picano ◽  
Pedro Costa ◽  
Wim-Paul Breugem ◽  
Luca Brandt
Keyword(s):  
Binary Mixture ◽  
Channel Flow ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Turbulent Channel Flow ◽  
Channel Height ◽  
Wall Region ◽  
Small Particles ◽  
Rigid Particles ◽  
Large Particles

We study turbulent channel flow of a binary mixture of finite-sized neutrally buoyant rigid particles by means of interface-resolved direct numerical simulations. We fix the bulk Reynolds number and total solid volume fraction, $Re_{b}=5600$ and $\unicode[STIX]{x1D6F7}=20\,\%$, and vary the relative fraction of small and large particles. The binary mixture consists of particles of two different sizes, $2h/d_{l}=20$ and $2h/d_{s}=30$ where $h$ is the half-channel height and $d_{l}$ and $d_{s}$ the diameters of the large and small particles. While the particulate flow statistics exhibit a significant alteration of the mean velocity profile and turbulent fluctuations with respect to the unladen flow, the differences between the mono-disperse and bi-disperse cases are small. However, we observe a clear segregation of small particles at the wall in binary mixtures, which affects the dynamics of the near-wall region and thus the overall drag. This results in a higher drag in suspensions with a larger number of large particles. As regards bi-disperse effects on the particle dynamics, a non-monotonic variation of the particle dispersion in the spanwise (homogeneous) direction is observed when increasing the percentage of small/large particles. Finally, we note that particles of the same size tend to cluster more at contact whereas the dynamics of the large particles gives the highest collision kernels due to a higher approaching speed.

An experimental study of the motion of concentrated suspensions in two-dimensional channel flow. Part 2. Bidisperse systems

1998 ◽  
Vol 363 ◽  
pp. 57-77 ◽  
Author(s):  
M. K. LYON ◽  
L. G. LEAL
Keyword(s):  
Large Particle ◽  
Particle Concentration ◽  
Volume Fraction ◽  
Balance Model ◽  
Concentration Profiles ◽  
Size Segregation ◽  
Small Particles ◽  
Concentrated Suspensions ◽  
Particle Volume ◽  
Large Particles

In this paper we report experimental velocity and concentration profiles for suspensions possessing a bidisperse distribution of particle size undergoing pressure-driven flow through a parallel-wall channel. In addition to the overall concentration distributions determined by implementing the modified laser Doppler velocimetry method described in Part 1 (Lyon & Leal 1998), concentration profiles for the particles of each size were measured by sampling the position of marked tracer particles across 60% of the channel gap. Non-uniform overall particle concentration distributions and blunted velocity profiles were found at bulk particle volume fractions of 0.30 and 0.40, which were equal to the monodisperse data of Part 1, within experimental uncertainty. The large-particle concentration profiles were non-uniform down to a large-particle bulk volume fraction of 0.075, while non-uniform distributions of the small particles were only found when the volume fraction of small particles in the bulk was greater than or equal to 0.20. Experiments in which at least half the suspended particulate volume was occupied by large particles revealed enrichment of the large particles in the centreline region of the channel. This size segregation was found to increase as the total number of suspended particles decreased. Finally, the data from experiments in which a uniform small-particle concentration profile was measured were compared with suspension balance model (McTigue & Jenkins 1992; Nott & Brady 1994) predictions for parameter values that corresponded only to the large particles. While close agreement with the large-particle concentration profiles was found, this comparison also reflected the fact that the small particles bring the suspension viscosity to a regime that is more sensitive to the particle concentration, rather than simply providing an increment in background viscosity to the suspending liquid.

scholarly journals Metal Composites Behaviour Under Biaxial Stresses

2017 ◽  
Vol 23 (4) ◽  
pp. 307
Author(s):  
J. Jai ◽  
M.N. Berhan
Keyword(s):  
Volume Fraction ◽  
Powder Metallurgy Method ◽  
Matrix Composites ◽  
Small Particles ◽  
Metal Composites ◽  
Large Particles ◽  
Before And After ◽  
The Matrix ◽  
Strong Interfacial Bonding ◽  
The Individual

For this study, different volume fraction (vol.%) of particulate alumina (Al2O3)reinforced aluminium alloy (Al 6061) with 5 vol.%, 15 vol.% and 25 vol.% are produced by powder metallurgy method. These samples were subjected to biaxial stresses in order to investigate the behaviour of the metal matrix composites (MMCs). Microstructure analysis on the individual sample before and after loading was performed under scanning electron microscopy. The small particles of 2 µm in size have exhibited strong interfacial bonding with the matrix. The particles of 5 µm in size have shown fractures and debonding interface. Large particles of above 20 µm in size have revealed severe fractures and particles pulled out. Behavior of the MMC was explained by relating the microstructures and displacement directions of the undeformed and deformed samples. Some understandings on the behaviour of the MMCs with different vol.% of Al2O3 due to biaxial stresses have been established.

scholarly journals Research on microstructure and forming mechanism of TiC/1Cr12Ni3Mo2V composite based on laser solid forming

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 334-339
Author(s):  
Wanli Ma ◽  
Fenghe Tao ◽  
Changzhi Jia ◽  
Xiangdong Men
Keyword(s):  
Electron Microscopy ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Small Particles ◽  
Microscopic Appearance ◽  
X Ray ◽  
Forming Mechanism ◽  
Laser Solid Forming ◽  
Large Particles ◽  
The Matrix

Abstract Samples of 1Cr12Ni3Mo2V-based composites with different TiC contents (The volume fraction of TiC were 0%, 10%, 20%, 30%, 40%) were prepared based on laser solid forming. Thermodynamic analysis was performed to estimate the possible chemical reactions. Phase analysis and microscopic topography analysis were characterized by optical microscopy (OM), scan electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). Finally, the formation mechanism of microscopic appearance was analyzed. The results indicate that the TiC particles were successfully dispersed in the matrix. TiC particles mainly exist in two ways in the matrix. The large particles were not completely melted and the small particles were decomposed and then precipitated. Their shape was mainly cross, plum-shaped or dendritic distribution with different TiC contents.

The Microstructures of As-Cast Mg-Zr and Mg-Mn Alloys

2005 ◽  
Vol 488-489 ◽  
pp. 329-332 ◽  
Author(s):  
Jian Ping Li ◽  
Gordon W. Lorimer ◽  
Joseph D. Robson ◽  
B. Davis
Keyword(s):  
Volume Fraction ◽  
Grain Structure ◽  
Small Particles ◽  
Fine Grain ◽  
Zr Addition ◽  
Large Particles ◽  
Mn Concentration ◽  
Zirconium Concentration ◽  
Zr Alloy ◽  
Zr Alloys

The as-cast microstructures of two dilute Mg-Zr and three dilute Mg-Mn alloys were studied using optical microscopy and scanning electron microscopy, including EDX analysis. The results show that the as-cast microstructure of the Mg-Zr alloys was composed of non-dendritic, equiaxed Mg grains, with a few Zr particles within the Mg grains and along grain boundaries. The grain size of the Mg-Zr alloy was significantly reduced by the Zr addition and a fine grain structure was achieved when the zirconium concentration was above 0.4wt. %. The as-cast structure of the Mg- Mn alloys contained columnar, dendritic grains. Two types of Mn particles (equiaxed large particles and rod-like or plate-like small particles) were observed in the as-cast Mg-Mn alloys. The volume fraction of particles and the size differences between the large and small particles increased with an increase of Mn concentration.

The Microstructure of Rapidly Solidified Al-Zn-Mg-Cu Alloys with Zr Addition

2010 ◽  
Vol 163 ◽  
pp. 42-45 ◽  
Author(s):  
Lidia Lityńska-Dobrzyńska ◽  
Patrick Ochin ◽  
Anna Góral ◽  
Marek Faryna ◽  
Jan Dutkiewicz
Keyword(s):  
Solid Solution ◽  
Melt Spinning ◽  
Volume Fraction ◽  
Cast Alloy ◽  
Dendritic Microstructure ◽  
X Ray ◽  
Cu Alloys ◽  
Transmission Electron ◽  
Cast Alloys ◽  
Rapidly Solidified

The effect of rapid solidification on the microstructure of Al-Zn-Mg-Cu alloys with 8 wt.% Zn-2 wt.% Mg-2.3 wt.% Cu and 0.2 or 0.5 wt.% of Zr additions were investigated using X-ray diffraction measurements (XRD), scanning (SEM) and transmission electron microscopy (TEM) combined with energy dispersive X-ray (EDX) microanalysis. Rapidly solidified ribbons with thickness of 70-100 m were performed by melt spinning technique. The mould cast alloys as well as the melt spun ribbons revealed dendritic microstructure of (Al) solid solution and η Mg(Zn,Cu)2 phase in interdendritic areas. The refinement of the microstructure and reduction of the volume fraction of the η phase up to 1.7%, as compared to 4% in the mould cast alloys was observed in the ribbons. Copper dissolution up to about 20 wt % in the η phase causes a decrease of the lattice parameters. The Al3Zr primary precipitates were observed in the mould cast alloy containing 0.5 wt % of Zr while in the ribbons all zirconium dissolved in the aluminium solid solution.

Fine Microstructure of a Mechanically Alloyed Oxide Dispersion Strengthened Nickel-Base Superalloy

1977 ◽  
Vol 35 ◽  
pp. 298-299
Author(s):  
Jordi Marti ◽  
Timothy E. Howson ◽  
David Kratz ◽  
John K. Tien
Keyword(s):  
Solid Solution ◽  
Volume Fraction ◽  
Stress Rupture ◽  
Oxide Dispersion Strengthened ◽  
Solid Solution Alloy ◽  
Oxide Dispersion ◽  
Creep And Stress Rupture ◽  
Mechanically Alloyed ◽  
Fine Microstructure ◽  
Nickel Base

The previous paper briefly described the fine microstructure of a mechanically alloyed oxide dispersion strengthened nickel-base solid solution. This note examines the fine microstructure of another mechanically alloyed system. This alloy differs from the one described previously in that it is more generously endowed with coherent precipitate γ forming elements A1 and Ti and it contains a higher volume fraction of the finely dispersed Y2O3 oxide. An interesting question to answer in the comparative study of the creep and stress rupture of these two ODS systems is the role of the precipitate γ' in the mechanisms of creep and stress rupture in alloys already containing oxide dispersoids.The nominal chemical composition of this alloy is Ni - 20%Cr - 2.5%Ti - 1.5% A1 - 1.3%Y203 by weight. The system receives a three stage heat treatment-- the first designed to produce a coarse grain structure similar to the solid solution alloy but with a smaller grain aspect ratio of about ten.

On the Origin of the Microscystalline Structure in Rapidly Solidified IN-100 Powder

1977 ◽  
Vol 35 ◽  
pp. 260-261
Author(s):  
J. M. Walsh ◽  
K. P. Gumz ◽  
J. C. Whittles ◽  
B. H. Kear
Keyword(s):  
The Other ◽  
Coarse Grained ◽  
Microcrystalline Structure ◽  
Routine Examination ◽  
Atomization Process ◽  
Centrifugal Atomization ◽  
Splat Quenching ◽  
Powder Particles ◽  
Dendritic Microstructures ◽  
Rapidly Solidified

During a routine examination of the microstructure of rapidly solidified IN-100 powder, produced by a newly-developed centrifugal atomization process1, essentially two distinct types of microstructure were identified. When a high melt superheat is maintained during atomization, the powder particles are predominantly coarse-grained, equiaxed or columnar, with distinctly dendritic microstructures, Figs, la and 4a. On the other hand, when the melt superheat is reduced by increasing the heat flow to the disc of the rotary atomizer, the powder particles are predominantly microcrystalline in character, with typically one dendrite per grain, Figs, lb and 4b. In what follows, evidence is presented that strongly supports the view that the unusual microcrystalline structure has its origin in dendrite erosion occurring in a 'mushy zone' of dynamic solidification on the disc of the rotary atomizer.The critical observations were made on atomized material that had undergone 'splat-quenching' on previously solidified, chilled substrate particles.

scholarly journals Nanoporous Quasi-High-Entropy Alloy Microspheres

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 345 ◽  
Author(s):  
Lianzan Yang ◽  
Yongyan Li ◽  
Zhifeng Wang ◽  
Weimin Zhao ◽  
Chunling Qin
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Hierarchical Porous

High-entropy alloys (HEAs) present excellent mechanical properties. However, the exploitation of chemical properties of HEAs is far less than that of mechanical properties, which is mainly limited by the low specific surface area of HEAs synthesized by traditional methods. Thus, it is vital to develop new routes to fabricate HEAs with novel three-dimensional structures and a high specific surface area. Herein, we develop a facile approach to fabricate nanoporous noble metal quasi-HEA microspheres by melt-spinning and dealloying. The as-obtained nanoporous Cu30Au23Pt22Pd25 quasi-HEA microspheres present a hierarchical porous structure with a high specific surface area of 69.5 m2/g and a multiphase approximatively componential solid solution characteristic with a broad single-group face-centered cubic XRD pattern, which is different from the traditional single-phase or two-phase solid solution HEAs. To differentiate, these are named quasi-HEAs. The synthetic strategy proposed in this paper opens the door for the synthesis of porous quasi-HEAs related materials, and is expected to promote further applications of quasi-HEAs in various chemical fields.

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