Hexagonal martensite decomposition and phase precipitation in Ti–Cu alloys

2011 ◽  
Vol 32 (8-9) ◽  
pp. 4608-4613 ◽  
Author(s):  
F.F. Cardoso ◽  
A. Cremasco ◽  
R.J. Contieri ◽  
E.S.N. Lopes ◽  
C.R.M. Afonso ◽  
...  
Keyword(s):  
Phase Precipitation ◽  
Cu Alloys

scholarly journals HREM imaging of single unit cell carbide precipitates in Pt-C alloys

1991 ◽  
Vol 49 ◽  
pp. 572-573
Author(s):  
M.J. Witcomb ◽  
U. Dahmen ◽  
M.A. O'Keefe ◽  
K.H. Westmacott
Keyword(s):  
Calcium Fluoride ◽  
Single Unit ◽  
Single Layer ◽  
Precipitation Process ◽  
Precipitate Phase ◽  
Precipitation Sequence ◽  
Phase Precipitation ◽  
Interstitial Solid Solution ◽  
Cu Alloys ◽  
Essential Function

Dilute Pt-C alloys are prototypical for studying oversize carbide phase precipitation from interstitial solid solution. Earlier studies showed the essential function of quenched-in vacancies in the precipitation process. Vacancies play a dual, volume accommodation and structural, role in the transformation by modifying both the habit plane spacing and stacking sequence. It was also shown how the precipitation sequence in interstitial Pt-C alloys is analogous to that in substitutional Al-Cu alloys. Initially a “GP zone” consisting of a monolayer plate of carbon atoms and vacancies forms. Atomic resolution images of the socalled a precipitates have confirmed their structure. During subsequent coarsening of the precipitates, α’ platelets form. Schematic diagrams illustrating the α and α’ structures in <100> projection are given in Fig. 1. The single-layer a structure, or GP zone is identical to a ﹛100﹜ stacking fault stabilized by an intercalation of carbon. The two-layer α’ structure is the first true precipitate phase and has a crystal structure anti-isomorphous with calcium fluoride.

scholarly journals CALPHAD-informed phase-field model for two-sublattice phases based on chemical potentials: η-phase precipitation in Al-Zn-Mg-Cu alloys

2021 ◽  
pp. 117602
Author(s):  
Chuanlai Liu ◽  
Alec Davis ◽  
Jonathan Fellowes ◽  
Philip B. Prangnell ◽  
Dierk Raabe ◽  
...  
Keyword(s):  
Phase Field ◽  
Field Model ◽  
Phase Field Model ◽  
Phase Precipitation ◽  
Chemical Potentials ◽  
Cu Alloys

Phase Diagram Simulation and Investigation of Microstructure of Ni-Based Alloys

2013 ◽  
Vol 634-638 ◽  
pp. 1826-1830
Author(s):  
Zhan Ping Zhang ◽  
Yu Hong Qi ◽  
Min Feng
Keyword(s):  
Phase Diagram ◽  
Sigma Phase ◽  
Equilibrium Phase ◽  
Equilibrium Temperature ◽  
S Phase ◽  
Solid Particles ◽  
Experimental Results ◽  
Large Temperature ◽  
Phase Precipitation ◽  
Cu Alloys

To develop proper Ni-based alloys for high-temperature vitriol pump which is submitted the corrosion of vitriol and rush of liquid with solid particles, the equilibrium phase diagrams of some Ni-Cr-Fe-C-Mo-Si-Cu alloys were calculated by software Thermo-Calc. Based on the simulation results and the mechanism of sigma phase precipitation strengthening, the chemical composition of a new Ni-based alloy was proposed. The alloy was casted and treated by solid solution at 1373K+2h, followed cooling to 1323K and quenching in water at room temperature, then strengthened by ageing respectively at 973K, 1023K, 1073K, 1123K for 4h. It was investigated the phases by XRD, the microstructures by OM and SEM. The proposed alloy consists of g, s and M23C6 from 1073K to 1273K. The most amount of s phase is up to 12.45 % (mass) at 1023K, it decreases with the augment of equilibrium temperature. s phase disappears above 1323K. The amount of s phase is enough in alloy to supply good precipitation hardening at a large temperature range. Experimental results were compared with the results of phase diagram simulation by Thermo-Calc. The alloy can be effectively strengthened by sigma phase precipitation at the temperature from 1023K to 1073K. Experimental results verified the validity of phase diagram simulation.

The Nature of Delta Phase Precipitation in Inconel 718

1982 ◽  
Vol 40 ◽  
pp. 724-725
Author(s):  
L. S. Lin ◽  
C. C. Law
Keyword(s):  
Inconel 718 ◽  
Base Alloy ◽  
High Strength ◽  
Physical Metallurgy ◽  
Nickel Base Alloy ◽  
Phase Precipitation ◽  
Weight Percentage ◽  
Delta Phase ◽  
The Subject ◽  
Nickel Base

Inconel 718, a precipitation hardenable nickel-base alloy, is a versatile high strength, weldable wrought alloy that is used in the gas turbine industry for components operated at temperatures up to about 1300°F. The nominal chemical composition is 0.6A1-0.9Ti-19.OCr-18.0Fe-3Mo-5.2(Cb + Ta)- 0.1C with the balance Ni (in weight percentage). The physical metallurgy of IN 718 has been the subject of a number of investigations and it is now established that hardening is due, primarily, to the formation of metastable, disc-shaped γ" an ordered body-centered tetragonal structure (DO2 2 type superlattice).

Plastic deformation of θ ' in Al-4%Cu alloy

1978 ◽  
Vol 36 (1) ◽  
pp. 576-577
Author(s):  
Shrikant P. Bhat
Keyword(s):  
Deformation Behavior ◽  
Room Temperature ◽  
Electron Microscopic Observation ◽  
Bulk Alloy ◽  
Electron Microscopic ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Orowan Mechanism ◽  
The Subject ◽  
Cyclic Straining

deformation behavior of Al-Cu alloys aged to contain θ ' has been the subject of many investigations (e.g., Ref. 1-5). Since θ ' is strong and hard, dislocations bypass θ ' plates (Orowan mechanism) at low strains. However, at high strains the partially coherent θ ' plates are probably sheared, although the mechanism is complex, depending on the form of deformation. Particularly, the cyclic straining of the bulk alloy is known to produce gross bends and twists of θ '. However, no detailed investigation of the deformation of θ ' has yet been reported; moreover, Calabrese and Laird interpreted the deformation of θ ' as largely being elastic.During an investigation of high temperature cyclic deformation, the detailed electron-microscopic observation revealed that, under reversed straining conditions, θ ' particles are severely distorted--bent and twisted depending on the local matrix constraint. A typical electronmicrograph, showing the twist is shown in Fig. 1. In order to establish whether the deformation is elastic or plastic, a sample from a specimen cycled at room temperature was heated inside the microscope and the results are presented in a series of micrographs (Fig. 2a-e).

Precipitation in Al-Li-Cu Alloys

1981 ◽  
Vol 39 ◽  
pp. 44-45
Author(s):  
J. E. O'Neal ◽  
K. K. Sankaran
Keyword(s):  
Electron Microscopy ◽  
Age Hardening ◽  
Precipitation Behavior ◽  
Zone Formation ◽  
Specific Strength ◽  
Hardening Behavior ◽  
Cu Alloys ◽  
High Specific Strength ◽  
Transmission Electron ◽  
Structural Applications

Al-Li-Cu alloys combine high specific strength and high specific modulus and are potential candidates for aircraft structural applications. As part of an effort to optimize Al-Li-Cu alloys for specific applications, precipitation in these alloys was studied for a range of compositions, and the mechanical behavior was correlated with the microstructures.Alloys with nominal compositions of Al-4Cu-2Li-0.2Zr, Al-2.5Cu-2.5Li-0.2Zr, and Al-l.5Cu-2.5Li-0.5Mn were argon-atomized into powder at solidification rates ≈ 103°C/s. Powders were consolidated into bar stock by vacuum pressing and extruding at 400°C. Alloy specimens were solution annealed at 530°C and aged at temperatures up to 250°C, and the resultant precipitation was studied by transmission electron microscopy (TEM).The low-temperature (≲100°C) precipitation behavior of the Al-4Cu-2Li-0.2Zr alloy is a combination of the separate precipitation behaviors of Al-Cu and Al-Li alloys. The age-hardening behavior at these temperatures is characteristic of Guinier-Preston (GP) zone formation, with additional strengthening resulting from the coherent precipitation of δ’ (Al3Li, Ll2 structure), the presence of which is revealed by the selected-area diffraction pattern (SADP) shown in Figure la.

Imaging of Al-Li-Cu alloys with a Scanning Ion Microprobe

1990 ◽  
Vol 48 (2) ◽  
pp. 314-315
Author(s):  
K.K. Soni ◽  
D.B. Williams ◽  
J.M. Chabala ◽  
R. Levi-Setti ◽  
D.E. Newbury
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Equilibrium Phase ◽  
Icosahedral Symmetry ◽  
Ion Microprobe ◽  
X Ray ◽  
Cu Alloys ◽  
Two Phases ◽  
The University ◽  
Secondary Ion

In contrast to the inability of x-ray microanalysis to detect Li, secondary ion mass spectrometry (SIMS) generates a very strong Li+ signal. The latter’s potential was recently exploited by Williams et al. in the study of binary Al-Li alloys. The present study of Al-Li-Cu was done using the high resolution scanning ion microprobe (SIM) at the University of Chicago (UC). The UC SIM employs a 40 keV, ∼70 nm diameter Ga+ probe extracted from a liquid Ga source, which is scanned over areas smaller than 160×160 μm2 using a 512×512 raster. During this experiment, the sample was held at 2 × 10-8 torr.In the Al-Li-Cu system, two phases of major importance are T1 and T2, with nominal compositions of Al2LiCu and Al6Li3Cu respectively. In commercial alloys, T1 develops a plate-like structure with a thickness <∼2 nm and is therefore inaccessible to conventional microanalytical techniques. T2 is the equilibrium phase with apparent icosahedral symmetry and its presence is undesirable in industrial alloys.

A STUDY OF G.P. ZONES IN Al-Cu ALLOYS BY ATOM-PROBE FIM

1986 ◽  
Vol 47 (C2) ◽  
pp. C2-171-C2-177 ◽  
Author(s):  
T. HASHIZUME ◽  
K. HONO ◽  
Y. HASEGAWA ◽  
K. HIRANO ◽  
T. SAKURAI
Keyword(s):  
Atom Probe ◽  
Cu Alloys
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