An Analysis of Diffusion Models of Hydrogen in Solid Solution Alloys of fcc and bcc Lattice Structures

1985 ◽  
Vol 146 (2) ◽  
pp. 215-215
Author(s):  
Y. Sakamoto
Keyword(s):  
Solid Solution ◽  
Diffusion Models ◽  
Lattice Structures ◽  
Bcc Lattice

scholarly journals Structure feature of ternary state diagrams of Cr-Ti-V and Cr-Mn-V systems

2018 ◽  
Vol 243 ◽  
pp. 00014 ◽  
Author(s):  
Anatoliy Klopotov ◽  
Irina Kurzina ◽  
Alexander Potekaev ◽  
Artem Ustinov ◽  
Taras Dement ◽  
...  
Keyword(s):  
Solid Solution ◽  
Intermetallic Compounds ◽  
Solid Solutions ◽  
Crystal Chemical ◽  
Electron Number ◽  
Isothermal Sections ◽  
State Diagrams ◽  
Bcc Lattice ◽  
Existence Domain ◽  
Chemical Factors

This paper presents the research results of features of structural and phase states in Cr-Ti-V and Cr-Mn-V systems based on analysis of crystal-geometric and crystal-chemical factors. The diagrams of isothermal sections of state diagrams of Cr-Ti-V and Cr-Mn-V systems were built in coordinates of the electron number (s+d) per atom with homogeneity regions of solid solutions and intermetallic compounds. It was shown that in the Cr-Ti-V system, addition of Mn atoms leads to substantial extension of the existence domain of the disordered solid solution based on the BCC lattice.

scholarly journals Theoretical Investigation of Phase Stability in Non-Magnetic Fe-V Substitutional Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
M. Sluiter ◽  
P.E.A. Turchi
Keyword(s):  
Phase Diagram ◽  
Solid Solution ◽  
Electronic Structure ◽  
Phase Stability ◽  
Tight Binding ◽  
Variation Method ◽  
Equiatomic Composition ◽  
Bcc Lattice ◽  
Slow Kinetics ◽  
Four Levels

The assessed phase diagram of Fe-V exhibits a continuous high temperature bcc solid solution intersected at lower temperatures by a complex sigma phase centered around equiatomic composition [1]. Slow kinetics of the bcc to sigma transformation make it possible to retain the bcc solid solution at low temperature. It has been observed that this metastable solid solution has a tendency to order with a CsCl type structure (B2) below 970 K [1,2]. As a first attempt to describe this behavior from an electronic structure approach, this paper will study the phase stability on the bcc lattice using a realistic tight-binding Hamiltonian. Details of the tight-binding description have been given elsewhere [3]. Main features are as follows: Element and structure specific Slater-Koster parameters are used [4] and lattice parameter effects are incorporated through scaling [5]. Charge transfer is set to zero by rigidly shifting the onsite energies of one constituent. The Coherent Potential Approximation (CPA) is invoked with four levels corresponding to states with s, p, t2g and eg like symmetry. Effects of off-diagonal disorder (ODD) have not been included, instead, an average alloy Hamiltonian was defined using the Slater-Koster parameters of the components weighted by concentration. At equiatomic composition the effect of this approximation has been evaluated by repeating the electronic structure calculation with inclusion of ODD effects (see also [6]). Effective pair interactions, as defined within the Generalized Perturbation Method (GPM) [7], have been computed and have been used to evaluate the ground states of configurational order on the bcc lattice in the Fe-V system. Furthermore, the theoretically derived energetic properties have been used to determine the phase diagram pertaining to the (metastable) bcc lattice with the Cluster Variation Method (CVM) [8] in the tetrahedron approximation

scholarly journals Improved Mechanical Properties and Energy Absorption of BCC Lattice Structures with Triply Periodic Minimal Surfaces Fabricated by SLM

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2411 ◽  
Author(s):  
Miao Zhao ◽  
Fei Liu ◽  
Guang Fu ◽  
David Zhang ◽  
Tao Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Computer Aided Design ◽  
Volume Fraction ◽  
Lattice Structure ◽  
The Body ◽  
Lattice Structures ◽  
Volume Fractions ◽  
Lattice Design ◽  
Bcc Lattice ◽  
Triply Periodic

The triply periodic minimal surface (TPMS) method is a novel approach for lattice design in a range of fields, such as impact protection and structural lightweighting. In this paper, we used the TPMS formula to rapidly and accurately generate the most common lattice structure, named the body centered cubic (BCC) structure, with certain volume fractions. TPMS-based and computer aided design (CAD) based BCC lattice structures with volume fractions in the range of 10–30% were fabricated by selective laser melting (SLM) technology with Ti–6Al–4V and subjected to compressive tests. The results demonstrated that local geometric features changed the volume and stress distributions, revealing that the TPMS-based samples were superior to the CAD-based ones, with elastic modulus, yield strength and compression strength increasing in the ranges of 18.9–42.2%, 19.2–29.5%, and 2–36.6%, respectively. The failure mechanism of the TPMS-based samples with a high volume fraction changed to brittle failure observed by scanning electron microscope (SEM), as their struts were more affected by the axial force and fractured on struts. It was also found that the TPMS-based samples have a favorable capacity to absorb energy, particularly with a 30% volume fraction, the energy absorbed up to 50% strain was approximately three times higher than that of the CAD-based sample with an equal volume fraction. Furthermore, the theoretic Gibson–Ashby mode was established in order to predict and design the mechanical properties of the lattice structures. In summary, these results can be used to rapidly create BCC lattice structures with superior compressive properties for engineering applications.

Analysis of the compression behaviour of different composite lattice designs

2017 ◽  
Vol 52 (6) ◽  
pp. 715-729 ◽  
Author(s):  
R Umer ◽  
Z Barsoum ◽  
HZ Jishi ◽  
K Ushijima ◽  
WJ Cantwell
Keyword(s):  
Lattice Structure ◽  
Numerical Models ◽  
Fibre Volume ◽  
Lattice Structures ◽  
Compression Tests ◽  
Static Compression ◽  
Bcc Lattice ◽  
Compression Behaviour ◽  
Composite Lattice ◽  
Quasi Static Compression

Four all-composite lattice designs were produced using a lost-mould procedure that involved inserting carbon fibre tows through holes in a core. Following resin infusion and curing, samples were heated to melt the core, leaving well-defined lattice structures based on what are termed BCC, BCCz, FCC and F2BCC designs. Analytical and numerical models for predicting the mechanical properties of the four designs are presented and these results are compared with the experimental data from the quasi-static compression tests. Compression tests on the four lattice structures indicated that the F2BCC lattice offered the highest compression strength, although when normalized by relative density, the BCCz lattice structure out-performed other structures. Similarly, the specific compression strengths were found to be superior to those of more traditional core materials. A number of failure mechanisms were also highlighted, including strut buckling, fracture at the strut-skin joints and debonding of reinforcing members at the central nodes. Finally, it is believed that the properties of these lattices can be further increased using higher fibre volume fractions.

NiAl precipitation in Fe-12w/o Cr-5w/o Ni-4w/o Al

1983 ◽  
Vol 41 ◽  
pp. 202-203
Author(s):  
L.E. Murr ◽  
J.S. Dunning ◽  
S. Shankar
Keyword(s):  
Solid Solution ◽  
Stainless Steel ◽  
Stainless Steels ◽  
Alloy Composition ◽  
Chromium Content ◽  
Scale Up ◽  
Optical Metallography ◽  
Property Evaluation ◽  
310 Stainless Steel ◽  
Microstructural Studies

Aluminum additions to conventional 18Cr-8Ni austenitic stainless steel compositions impart excellent resistance to high sulfur environments. However, problems are typically encountered with aluminum additions above about 1% due to embrittlement caused by aluminum in solid solution and the precipitation of NiAl. Consequently, little use has been made of aluminum alloy additions to stainless steels for use in sulfur or H2S environments in the chemical industry, energy conversion or generation, and mineral processing, for example.A research program at the Albany Research Center has concentrated on the development of a wrought alloy composition with as low a chromium content as possible, with the idea of developing a low-chromium substitute for 310 stainless steel (25Cr-20Ni) which is often used in high-sulfur environments. On the basis of workability and microstructural studies involving optical metallography on 100g button ingots soaked at 700°C and air-cooled, a low-alloy composition Fe-12Cr-5Ni-4Al (in wt %) was selected for scale up and property evaluation.

Solid Solution Effects and Deformation Micros trueture of Shock-Loaded Iron Manganese Alloys

1970 ◽  
Vol 28 ◽  
pp. 420-421
Author(s):  
A. Christou ◽  
J. V. Foltz ◽  
N. Brown
Keyword(s):  
Solid Solution ◽  
Shock Loading ◽  
High Strain ◽  
Local Stress ◽  
Strain Rates ◽  
Local Stress Concentration ◽  
Bcc Metals ◽  
Manganese Alloys ◽  
Iron Manganese ◽  
Transmission Microscope

In general, all BCC transition metals have been observed to twin under appropriate conditions. At the present time various experimental reports of solid solution effects on BCC metals have been made. Indications are that solid solution effects are important in the formation of twins. The formation of twins in metals and alloys may be explained in terms of dislocation mechanisms. It has been suggested that twins are nucleated by the achievement of local stress-concentration of the order of 15 to 45 times the applied stress. Prietner and Leslie have found that twins in BCC metals are nucleated at intersections of (110) and (112) or (112) and (112) type of planes.In this paper, observations are reported of a transmission microscope study of the iron manganese series under conditions in which twins both were and were not formed. High strain rates produced by shock loading provided the appropriate deformation conditions. The workhardening mechanisms of one alloy (Fe - 7.37 wt% Mn) were studied in detail.

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.

The Precipitation of Si in AlCuSi Thin Films

1973 ◽  
Vol 31 ◽  
pp. 34-35 ◽  
Author(s):  
R. M. Anderson
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Heat Treatment ◽  
Solid Solution ◽  
Integrated Circuit ◽  
Copper Film ◽  
Solution Concentration ◽  
X Ray ◽  
Silicon Thin Films ◽  
Before And After

Aluminum-copper-silicon thin films have been considered as an interconnection metallurgy for integrated circuit applications. Various schemes have been proposed to incorporate small percent-ages of silicon into films that typically contain two to five percent copper. We undertook a study of the total effect of silicon on the aluminum copper film as revealed by transmission electron microscopy, scanning electron microscopy, x-ray diffraction and ion microprobe techniques as a function of the various deposition methods.X-ray investigations noted a change in solid solution concentration as a function of Si content before and after heat-treatment. The amount of solid solution in the Al increased with heat-treatment for films with ≥2% silicon and decreased for films <2% silicon.

Backscattered Electron Imaging of GaAs/AlGaAs Super Lattice Structures with an Ultra-High- Resolution SEM

1988 ◽  
Vol 46 ◽  
pp. 204-205
Author(s):  
Kazumichi Ogura ◽  
Michael M. Kersker
Keyword(s):  
High Resolution ◽  
Layer Structure ◽  
High Sensitivity ◽  
Beam Current ◽  
Electron Beam Current ◽  
Lattice Structures ◽  
Super Lattice ◽  
Different Types ◽  
Backscattered Electron ◽  
Electron Imaging

Backscattered electron (BE) images of GaAs/AlGaAs super lattice structures were observed with an ultra high resolution (UHR) SEM JSM-890 with an ultra high sensitivity BE detector. Three different types of super lattice structures of GaAs/AlGaAs were examined. Each GaAs/AlGaAs wafer was cleaved by a razor after it was heated for approximately 1 minute and its crosssectional plane was observed.First, a multi-layer structure of GaAs (100nm)/AlGaAs (lOOnm) where A1 content was successively changed from 0.4 to 0.03 was observed. Figures 1 (a) and (b) are BE images taken at an accelerating voltage of 15kV with an electron beam current of 20pA. Figure 1 (c) is a sketch of this multi-layer structure corresponding to the BE images. The various layers are clearly observed. The differences in A1 content between A1 0.35 Ga 0.65 As, A1 0.4 Ga 0.6 As, and A1 0.31 Ga 0.69 As were clearly observed in the contrast of the BE image.

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