Investigation of a New Type of Al3Ti-Based Ll2 Alloy With Second Phase Precipitation

1994 ◽  
Vol 364 ◽  
Author(s):  
Gengxiang Hu ◽  
Jian Sun ◽  
Xiaojun Weng ◽  
Tong Li ◽  
Shipu Chen
Keyword(s):  
Single Phase ◽  
Solution Treatment ◽  
Second Phase ◽  
Quaternary Alloys ◽  
Two Phase ◽  
Ti Alloys ◽  
Second Phase Particles ◽  
New Type ◽  
Temperature Aging ◽  
Nb Additions

AbstractSince the L12 structured Al3Ti alloy exists only in a narrow compositional range, further alloying of the single phase Ll2 alloy to improve its property seems hardly successful. Developing two-phase or multiphase Al3Ti alloys may be an effective approach for strengthening and toughening. In this article, a new type of Al3Ti-based alloy which has a Ll2 matrix with precipitates of a second phase is reported. The quaternary alloys based on Al67Mn8Ti25, and modified with Nb additions, consist of an Ll2 matrix and DO22 second phase particles in the annealed state, but the second phase can be dissolved by solution treatment and precipitated during high temperature aging. Remarkable strenghtening and promising compressive ductility were exhibited by the experimental alloy. The influence of composition on the microstructure and properties of the alloys are reported also.

Recent Advances on the Deformation Behavior of Two-Phase α+β Titanium Alloys

2019 ◽  
Vol 950 ◽  
pp. 55-59 ◽  
Author(s):  
Sreeramamurthy Ankem ◽  
William J. Joost ◽  
Samuel C. Schwarm
Keyword(s):  
Deformation Behavior ◽  
Single Phase ◽  
Elastic Interaction ◽  
Deformation Mechanisms ◽  
Second Phase ◽  
General Will ◽  
Two Phase ◽  
Ti Alloys ◽  
The Difference ◽  
The Individual

Two-phase materials, such as α+β Titanium (Ti) alloys, are technologically important. A number of factors can affect deformation behavior, including the interaction stresses between phases, the crystallographic relationships between phases, and the morphology. As a result, the deformation mechanisms of two-phase alloys may be different from the individual single-phase materials. For example, twinning may not occur in a single phase material if the grain size is very small but twinning can occur in a very fine grained alloy if the second phase contributes to the interfacial stresses due to elastic interactions. Interaction stresses can result from the difference in the elastic properties of the two phases. In particular, these elastic interaction stresses can be quantified by the finite element method (FEM). In this paper recent developments regarding two-phase deformation mechanisms will be reviewed and the ramifications on mechanical behavior in regard to two-phase Ti alloys in particular and on two-phase metallic materials in general will be outlined.

Composition-induced microstructures in rhombohedral carbonates

1987 ◽  
Vol 51 (359) ◽  
pp. 71-86 ◽  
Author(s):  
D. J. Barber ◽  
M. Riaz Khan
Keyword(s):  
Electron Diffraction ◽  
Crystallographic Orientation ◽  
Solid Solubility ◽  
Single Phase ◽  
Crystal Defects ◽  
Second Phase ◽  
Two Phase ◽  
Diffraction Contrast ◽  
Second Phases ◽  
Metallic Impurities

AbstractRecent TEM observations of two-phase microstructures and associated crystal defects in selected, rare dolomites have been extended to calcite-structured (R3̄c) carbonates and to other natural and synthetic carbonates that crystallize with the dolomite (R3̄) structure. The samples included siderites (FeCO3), smithsonites (ZnCO3), ankerites (Ca[Mg,Fe](CO3)2), and kutnahorites (Ca[Mn,Fe](CO3)2).TEM methods show that the forms of second phases which result from the presence of common, divalent, metallic impurities are morphologically similar in R3̄c and R3̄ carbonates and occur more widely than hitherto realized. The most common form consists of thin ribbons of second phase which are coherent with and have the same crystallographic orientation as the host carbonate. Another form of microstructure, manifest as modulations in diffraction contrast, appears to be associated with incipient breakdown of single-phase carbonate. The results of extensive TEM/EDS microanalyses show that in siderite and ankerite the formation of ribbons is promoted by Ca impurity or Ca excess (with respect to R3̄c stoichiometry). In smithsonite, Cu and Ca impurities can play similar roles in relation to modulated microstructures. In kutnahorites, the perfection of grains and the absence of second-phase effects is strongly dependent on the ratio of Fe to Mn but is also affected by Ca in excess of the stoichiometric requirement. Electron diffraction results from several of the minerals show c-type spots, which can be interpreted as indicating ordering within basal layers of cations.The results show that, by correlating analytical TEM data with the study of second phases and incipient two-phase microstructures, it should be possible to determine the limits of solid solubility in carbonate systems.

3D MС Simulation of Grain Growth Kinetics and the Zener Limit in Polycrystals

2014 ◽  
Vol 598 ◽  
pp. 8-12
Author(s):  
K.R. Phaneesh ◽  
Anirudh Bhat ◽  
Gautam Mukherjee ◽  
Kishore T. Kashyap
Keyword(s):  
Monte Carlo ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Large Scale ◽  
Volume Fraction ◽  
Growth Exponent ◽  
Cube Root ◽  
Second Phase ◽  
Two Phase ◽  
Second Phase Particles

Large scale Potts model Monte Carlo simulation was carried on 3-dimensional square lattices of 1003 and 2003 sizes using the Metropolis algorithm to study grain growth behavior. Simulations were carried out to investigate both growth kinetics as well as the Zener limit in two-phase polycrystals inhibited in growth by second phase particles of single-voxel size. Initially the matrices were run to 10,000 Monte Carlo steps (MCS) to check the growth kinetics in both single phase and two-phase poly-crystals. Grain growth exponent values obtained as a result have shown to be highest (~ 0.4) for mono-phase materials while the value decreases with addition of second phase particles. Subsequently the matrices were run to stagnation in the presence of second phase particles of volume fractions ranging from 0.001to 0.1. Results obtained have shown a cube root dependence of the limiting grain size over the particle volume fraction thus reinforcing earlier 3D simulation efforts. It was observed that there was not much difference in the values of either growth kinetics or the Zener limit between 1003 and 2003 sized matrices, although the results improved mildly with size.

scholarly journals Assessment of the Compositional Influences on the Toughness of TiCr2-Base Laves Phase Alloys

1996 ◽  
Vol 460 ◽  
Author(s):  
Katherine C. Chen ◽  
Samuel M. Allen ◽  
James D. Livingston
Keyword(s):  
Crystal Structure ◽  
Single Phase ◽  
Laves Phase ◽  
Second Phase ◽  
Vickers Indentation ◽  
Toughening Mechanisms ◽  
Two Phase ◽  
Laves Phases ◽  
Effective Factors ◽  
Alloying Effects

ABSTRACTSystematic studies of alloys based on TiCr2 have been performed in order to improve the toughness of Laves phase intermetallics. The extent to which alloy compositions and annealing treatments influence the toughness was quantified by Vickers indentation. The single-phase Laves behavior was first established by studying stoichiometric and nonstoichiometric TiCr2. Next, alloying effects were investigated with ternary Laves phases based on TiCr2. Different microstructures of two-phase alloys consisting of (Ti,Cr)-bcc+TiCr2 were also examined. Various toughening theories based on vacancies, site-substitutions, crystal structure (C14, C36, or C15) stabilization, and the presence of a second phase were evaluated. The most effective factors improving the toughness of TiCr2 were determined, and toughening mechanisms are suggested.

scholarly journals Influence of Grain Refinement on Oxidation Behavior of Two-Phase Cu–Cr Alloys at 973–1,073 K in Air

2016 ◽  
Vol 35 (10) ◽  
pp. 1005-1011
Author(s):  
T. J. Pan ◽  
J. Chen ◽  
Y. X. He ◽  
W. Wei ◽  
J. Hu
Keyword(s):  
Grain Size ◽  
Spatial Distribution ◽  
Oxidation Behavior ◽  
Second Phase ◽  
Two Phase ◽  
Reactive Component ◽  
Parabolic Law ◽  
Second Phase Particles ◽  
Kinetics Of ◽  
Lower Oxidation

AbstractThe oxidation behavior of grain-refined Cu–7.0 Cr alloy (GR Cu–7.0 Cr) in air at 973–1,073 K was investigated in comparison with normal casting Cu–7.0 Cr alloy (CA Cu–7.0 Cr). The oxidation of CA Cu–7.0 Cr alloy nearly followed parabolic law, while the oxidation kinetics of GR Cu–7.0 Cr slightly deviated from parabolic law. Both alloys almost produced multi-layered scales consisting of the outer layer of CuO and the inner layer of mixed Cr2O3 and Cu2O oxides plus internal oxidation zones of chromium. The grain-refined Cu–7.0 Cr alloy produced a more amount of Cr2O3 in the inner layer of the scale, and thus was oxidized at much lower oxidation rate than that of CA Cu–7.0 Cr with normal grain size. The experimental results indicated that the differences in oxidation behavior between two alloys may be ascribed to the different size and spatial distribution of the second-phase particles and the reactive component contents in localized zone.

scholarly journals Design and development of a dual-phase TRIP-TWIP alloy for enhanced mechanical properties

2020 ◽  
Vol 321 ◽  
pp. 11014
Author(s):  
Lola Lilensten ◽  
Yolaine Danard ◽  
Fan Sun ◽  
Philippe Vermaut ◽  
Loïc Perrière ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Single Phase ◽  
Second Phase ◽  
Dual Phase ◽  
Body Centered Cubic ◽  
Transformation Induced Plasticity ◽  
Ti Alloys ◽  
Semi Empirical ◽  
Alloy Analysis

Triggering transformation induced plasticity (TRIP) and twinning induced plasticity (TWIP) mechanisms in metastable β titanium alloys (bcc, body centered cubic) have helped reaching unprecedented mechanical properties for Ti-alloys, including high ductility and work-hardening. Yet the yield strength of such alloys generally remains rather low. So far, mostly single-phase metastable bcc alloys have been developed. In this study, a dual phase TRIP/TWIP alloy is designed and investigated. While the β-matrix is expected to display TRIP/TWIP deformation mechanisms, the addition of a second phase, α in the present study, aims at increasing the yield strength. The composition was designed in the Ti-Cr-Sn system, based on Calphad prediction and on the semi-empirical d-electron alloy design approach. Results were compared to the published full β Ti – 8.5Cr – 1.5Sn (wt%) TRIP/TWIP alloy. The dual-phase alloy was prepared and processed to reach the desired microstructure containing about 20% α. It displays remarkable mechanical properties such as a ductility of 29%, an ultimate tensile strength of 1200 MPa and a yield strength of 760 MPa, 200MPa higher than the Reference single-phase β alloy. Analysis of the mechanical properties and deformation microstructures confirm the TRIP and TWIP effects, validating the proposed approach.

scholarly journals Evolution of the Second-Phase Particles and Their Effect on Tensile Fracture Behavior of 2219 Al-xCu Alloys

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 197
Author(s):  
Daofen Xu ◽  
Kanghua Chen ◽  
Yunqiang Chen ◽  
Songyi Chen
Keyword(s):  
Fracture Behavior ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Fracture Initiation ◽  
Tensile Tests ◽  
Tensile Fracture ◽  
Second Phase ◽  
Cu Content ◽  
Second Phase Particles ◽  
Microcrack Propagation

In this study, the continuous evolution of the second-phase particles across as-cast, homogenization, multi-directional forging (MDF), and solution-aging treatment and their effect on tensile fracture behavior of 2219 aluminum alloys with different Cu contents was examined by optical microscopy (OM), scanning electron microscopy (SEM), and tensile tests. The results showed that the microstructure of as-cast 2219 aluminum alloy consisted of the α-Al matrix, Al2Cu coarse phase, and Fe-rich impurity phase. Severe segregation of Cu existed, and eutectic networks can be observed in the ingot. With an increase in Cu content, the eutectic networks became coarsen and thicker. During the complex improved process, the refinement mechanisms were fragmentation, dissolution, and diffusion of Al2Cu particles. Most fine Al2Cu particles were fully dissolved into the matrix and partial coarse particles were still retained after solution-aging treatment. Thus, the elongations of all the samples, undergoing solution treatment followed by water quenching, increased evidently. Then, the elongations decreased slightly due to the increase of precipitates. The fractography analysis of peak aged condition samples indicated that the fracture mode was diverted from a typical inter-granular fracture to a mainly trans-granular fracture with increase in Cu content from 5.56% to 6.52%. Fracture initiation mainly occurred by original microcrack propagation and microvoid nucleation at the coarse constituents.

Measuring and Modelling the Microstructures of Two-Phase Aluminium Alloys after Deformation

2012 ◽  
Vol 715-716 ◽  
pp. 23-32 ◽  
Author(s):  
John F. Humphreys ◽  
Pete S. Bate ◽  
Ali Gholinia ◽  
Ian Brough
Keyword(s):  
Aluminium Alloys ◽  
Second Phase ◽  
Two Phase ◽  
New Techniques ◽  
Deformation Microstructure ◽  
Deformation Structures ◽  
Deformable Particles ◽  
Second Phase Particles ◽  
Cold Rolled ◽  
Ebsd Method

The effect of second-phase particles on the deformation and annealing behaviour of metals is re-assessed in the light of some new techniques. Using an EBSD method which provides much improved angular resolution, the effect of small non-deformable particles on the homogeneity of the deformation microstructure has been quantified. The presence of micron sized second-phase particles alters the deformation microstructure adjacent to particles, and a 3-d investigation of the deformation structures associated with large (>1μm) second-phase particles in cold rolled aluminium alloys has been carried out using 3-d FIB sectioning combined with EBSD, and the microstructures compared with the predictions of 3-d CPFEM modelling. The effects of grain orientation, strain and particle size have been investigated, and the results compared with earlier TEM investigations of such microstructures.

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