Microstructure of Al-Cu, Al-Zn, Al-Ag-Zn, and Al-Zn-Mg Alloys

2019 ◽  
Author(s):  
Željko Skoko ◽  
Stanko Popović
Keyword(s):  
Solid Solution ◽  
Phase Transitions ◽  
Room Temperature ◽  
Thermal Hysteresis ◽  
Solution Temperature ◽  
The Matrix ◽  
History Of ◽  
Precipitate Shape ◽  
Precipitation Phenomena

The precipitation phenomena and their connection with the microstructure of several Al alloys (Al-Cu, Al-Zn, Al-Ag-Zn, Al-Zn-Mg) are described with respect to the concentration and applied thermal treatment. The alloys were rapidly quenched or slowly cooled from a temperature higher than the solid solution temperature to room temperature. Both quenched-aged and slowly cooled alloys were heated from room temperature to the solid solution state and cooled back to room temperature, and their microstructure and precipitation phenomena were followed in situ by X-ray powder diffraction, e.g., anisotropy of thermal expansion, phase transitions, thermal hysteresis in phase transitions, change of precipitate shape, partial or complete dissolution of precipitates in the matrix, and formation of solid solution. It has been shown that the microstructure strongly depends on the previous thermal history of the alloys.

Effect of Heat Treatment on the Structure and Properties of EW75 Magnesium Alloy Plate

2013 ◽  
Vol 747-748 ◽  
pp. 158-165
Author(s):  
Juan Qu ◽  
Kui Zhang ◽  
Ming Long Ma ◽  
Yong Jun Li ◽  
Xing Gang Li
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Tensile Strength ◽  
Solution Process ◽  
Solution Time ◽  
Solution Temperature ◽  
Second Phase ◽  
Alloy Plate ◽  
T6 Heat Treatment ◽  
The Matrix

In this study, Mg-7Gd-5Y-1Nd-0.5Zr alloy (EW75) was produced by melting method and then press-forged into large size plate. The properties of the Mg-7Gd-5Y-1.2Nd-0.5Zr alloy were optimized through T6 heat treatment. The microstructures of alloy were observed by means of optical microscopy (OM), scanning electron microscopy (SEM). Its mechanical properties under different heat treatment conditions were determined by tensile tests. The results indicated that increasing the solid solution temperature and prolonging the solid solution time can both lead to the dissolution of second phase in the alloy back into the matrix. The solid solution temperature affects the dissolution process more than the solid solution time. Grain growth occurred during the solid solution process. The grain size of the matrix enlarges with the increase of solid solution temperature. The tensile test result showed that the tensile strength of the alloy was significantly improved after T6 heat treatment. Its tensile strength in the same direction was nearly 40% up after T6 heat treatment. The analysis shows that T6 heat treatment can effectively eliminate the larger deformed precipitates and beneficial to the formation of hard precipitates, which leads to an improvement in the alloys tensile strength.

Influences of the γ′ Phase on the Mechanical Properties of a Nickel-Based Single Crystal Superalloy

2021 ◽  
Vol 1023 ◽  
pp. 45-52
Author(s):  
Xiao Yan Wang ◽  
Meng Li ◽  
Zhi Xun Wen
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Single Crystal ◽  
Tensile Properties ◽  
Room Temperature ◽  
Solution Treatment ◽  
Single Crystal Superalloy ◽  
Original Material ◽  
Solid Solution Treatment ◽  
The Matrix

After solid solution treatment at 1335°C for 4 hours and cooling to room temperature at different rate, the nickel-based single crystal superalloy were made into three kinds of nickel-based single crystal superalloy materials containing different size γ′ phases, respectively. The tensile test of I-shaped specimens was carried out at 980°C, and their effect of γ′ phase microstructure on the tensile properties was studied. The results show that the yielding strength of the material air-cooled to room temperature was lower than that with cooling rate at 0.15°C/s, but both of them were lower than the yielding strength of original material. Little difference was found on the elastic modulus of I-shaped specimens made of three kinds of materials. When the cubic degree of the γ′ phase is higher and the size is larger, the tensile properties of the material is better, which can be attributed to the larger size and narrower channel of the matrix phase that lead to higher dislocation resistance.

Solidification Processing Routes to High Aspect Ratio Reinforcements in γ-TiAl

1990 ◽  
Vol 194 ◽  
Author(s):  
J. J. Valencia ◽  
J. P. A. Löfvander ◽  
J. Rösler ◽  
C. G. Levi ◽  
R. Mehrabian
Keyword(s):  
Solid Solution ◽  
Aspect Ratio ◽  
Creep Strength ◽  
High Aspect Ratio ◽  
Anisotropic Growth ◽  
Solidification Processing ◽  
Aspect Ratios ◽  
The Matrix ◽  
Solute Strengthening

AbstractAdditions of ∼5%B1 and ∼9%Ta to binary γ-TiAl result in the formation of a monoboride isomorphous with TiB but containing Ta in solid solution. This boride exhibits strongly anisotropic growth from the melt, producing rod-like primary phases which are of potential interest for creep strengthening of the γ matrix. Fibrous borides with aspect ratios larger than ∼20 and volume fractions of ∼0.12 have been produced in arc-melted Ti-48AI-9Ta-4.3B alloys. Creep testing at 1255 K indicates that these “in-situ” composites have much higher creep strength than γ-TiAl, but the contribution of the reinforcements is relatively small compared with the solute-strengthening of the matrix.

Synthesis of SiCW/(Mo,W)Si2 Composite by the "Chemical Oven" Self-Propagating Combustion Method

2008 ◽  
Vol 368-372 ◽  
pp. 951-954 ◽  
Author(s):  
Jian Guang Xu ◽  
Hou An Zhang ◽  
Guo Jian Jiang ◽  
Wen Lan Li
Keyword(s):  
Solid Solution ◽  
Flexural Strength ◽  
Room Temperature ◽  
Composite Powder ◽  
Cost Effective ◽  
Combustion Method ◽  
Sintering Process ◽  
High Temperature Synthesis ◽  
Result Show

SiC whisker reinforced (Mo,W)Si2 composite powder has been successfully synthesized by a novel process, named as chemical oven self-propagating high temperature synthesis (COSHS). The mixtures of Si and Ti powders were ignited as chemical oven. XRD result shows that the combustion product is mainly composed of (Mo,W)Si2 solid solution and SiC phases. SEM photo and EDS result show that SiC whisker is formed during this process. The as-prepared SiCW/(Mo,W)Si2 composite powder has been pressureless sintered. The microstructure and mechanical properties of the composite were investigated. Relative densities of the monolithic material and composite are 91.2% and 92.2%, respectively. The composite containing SiC whisker and (Mo,W)Si2 solid solution has higher Vickers hardness than monolithic MoSi2. Especially the room-temperature flexural strength of the composite is higher than that of monolithic MoSi2, from 135.5MPa for MoSi2 to 235.6MPa for composites with 10 vol.% WSi2 and 15 vol.% SiC, increased by 73.9%. The morphology of fractured surface of composite reveals the mechanism to improve flexural strength of MoSi2. The results of this work show that in situ SiCW/(Mo,W)Si2 composite powder prepared by COSHS technique could be successfully sintered via pressureless sintering process and significant improvement of room temperature flexural strength could be achieved. It could be a cost-effective process for industry in future applications.

Phase Transitions and Recrystallization in a Ti-46at%Al-9at%Nb Alloy as Observed by In-Situ High-Energy X-ray Diffraction

2006 ◽  
Vol 980 ◽  
Author(s):  
Klaus-Dieter Liss ◽  
Helmut Clemens ◽  
Arno Bartels ◽  
Andreas Stark ◽  
Thomas Buslaps
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Strain Relaxation ◽  
Reciprocal Lattice ◽  
Lamellar Microstructure ◽  
High Energy ◽  
X Ray Diffraction ◽  
Orientation Relationships ◽  
X Ray

AbstractHigh-energy synchrotron X-ray diffraction is a powerful tool for bulk studies of materials. In this investigation, it is applied to the investigation of an intermetallic γ-TiAl based alloy with a composition of Ti-46Al-9Nb. The morphology of the reflections on the Debye-Scherrer rings is evaluated in order to approach grain sizes as well as crystallographic correlations. An in-situ heating cycle from room temperature to a temperature above the α-transus temperature has been conducted starting from a massively transformed sample. With increasing temperature the occurrence of strain relaxation, chemical and phase separation, domain orientations, phase transitions, recrystallization processes, and subsequent grain growth can be observed. During cooling to room temperature, crystallographic correlations between the re-appearing γ-phase and the host α-phase, known as the Blackburn correlation, are observed in the reciprocal lattice, which splits into different twinning and domain orientation relationships present in the fully lamellar microstructure.

A tem study of amorphization in Niti irradiated with Ni2+ ions at room temperature

1987 ◽  
Vol 45 ◽  
pp. 220-221
Author(s):  
P. J. Maziasz ◽  
N. H. Packan ◽  
D. F. Pedraza ◽  
E. H. Lee
Keyword(s):  
Solid Solution ◽  
Amorphous Alloys ◽  
Room Temperature ◽  
Crystalline Solid ◽  
Thick Sheet ◽  
Scientific Interest ◽  
The Matrix ◽  
Memory Applications ◽  
B2 Structure ◽  
Insight Into

Irradiation of a crystalline solid solution can cause the decomposition of the matrix into enhanced, modified thermal, or irradiation-induced precipitate phases. Irradiation can also transform the matrix into a new crystalline phase. Alternatively, the heavily irradiated matrix can become amorphous. Alloys of NiTi are intermetallic compounds with shape-memory applications whose amorphization is of both technological and basic scientific interest. Our purpose is to observe some details of the intermediate stages of amorphization to provide further insight into the mechanisms of the phenomenon.An alloy of 50.5 at.% Ni/49.5% Ti was obtained from Raychem Co. as 0.76-mm- thick sheet and then rolled to 0.5 mm sheet. Disks 3 mm in diameter were punched and annealed for 0.5 h at 850°C. This results in an ordered austenitic (B2) structure, which partially transforms to martensite after air quenching.

An In-situ Electron Microscopy Study of Microstructural Evolution in a Co-NbCo2 Binary Alloy

2008 ◽  
Vol 1128 ◽  
Author(s):  
Sharvan Kumar ◽  
Padam Jain ◽  
Seong Woong Kim ◽  
Frank Stein ◽  
Martin Palm
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Laves Phase ◽  
Face Centered Cubic ◽  
The Matrix ◽  
The Individual ◽  
Individual Grains

AbstractThe microstructure in a Co-rich, Co-15 at.% Nb alloy was characterized in the as-cast condition. A predominantly lamellar eutectic morphology composed of a Co-Nb solid solution and the C15 Laves phase NbCo2 was confirmed by transmission electron microscopy. The C15 phase was heavily twinned, with only one variant of twins being present in the individual lamella, while the Co solid solution had the face centered cubic structure. In-situ heating to 600°C in the microscope confirmed the decomposition of the metastable Laves phase into a fine equiaxed, ˜10-20 nm grain size microstructure, and the product phase is the monoclinic Nb2Co7. The individual grains appear faulted. The matrix solid solution retained the fcc structure and no change in structure was observed on cooling to room temperature. Heating to temperatures as high as 1130°C leads to rapid grain growth in the Nb2Co7 phase, and the nucleation and growth of a few new grains within the original grains; however, the reverse peritectoid transformation previously reported, was not observed.

scholarly journals Combinatorial discovery of small-molecule 1,2,3-triazolium ionic liquids exhibiting lower critical solution temperature phase transition

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yen-Ho Chu ◽  
Mou-Fu Cheng ◽  
Yung-Hsin Chiang
Keyword(s):  
Phase Transition ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Phase Transitions ◽  
Small Molecule ◽  
Room Temperature ◽  
Solution Temperature ◽  
Temperature Phase ◽  
Critical Solution Temperature ◽  
True Value

Abstract Both lower and upper critical solution temperature (LCST and UCST) systems are two typical phase behaviors of thermoresponsive materials with solvents, in which LCST is far less common than UCST. Recent studies on ionic liquids carrying LCST phase transitions have predominantly focused on quaternary ammonium- and phosphonium-based ionic salts. Based on the 1,2,3-triazole core structure assemblable by azide-alkyne cycloaddition click reaction, this work reports the combinatorial synthesis of 1,3,4-trialkylated 1,2,3-triazolium ionic liquids in three libraries with a total of 160 ionic liquids and demonstrates, for the first time, their values in temperature-switchable phase transition with water. In this work, the successful discovery of a new thermoresponsive ionic liquid b26, based on the structure-and-phase separation study of b8 and b9, perfectly exemplified the true value of the tunability of ionic liquid fine structures. For all 160 ionic liquids synthesized, 155 are liquid at room temperature and 22 room-temperature ionic liquids were found to exhibit thermoresponsive phase transitions having low Tc values in water. To the best of our knowledge, this comprehensive study is the first report of small-molecule 1,2,3-triazolium ionic liquids that exhibit LCST property in water.

Microstructures and Mechanical Properties of NiAl+Mo In-Situ Eutectic Composites

1990 ◽  
Vol 194 ◽  
Author(s):  
P. R. Subramanian ◽  
M. G. Mendiratta ◽  
D. B. Miracle ◽  
D. M. Dimiduk
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Room Temperature ◽  
Composite System ◽  
Elevated Temperatures ◽  
Two Phase ◽  
Structural Applications ◽  
Temperature Fracture

AbstractThe quasibinary NiAI-Mo system exhibits a large two-phase field between NiAl and the terminal (Mo) solid solution, and offers the potential for producing in-situ eutectic composites for high-temperature structural applications. The phase stability of this composite system was experimentally evaluated, following long-term exposures at elevated temperatures. Bend strengths as a function of temperature and room-temperature fracture toughness data are presented for selected NiA1-Mo alloys, together with results from fractography observations.

STUDY ON PREPARING Al2O3 PARTICLES REINFORCED ZL109 COMPOSITE BY IN SITU REACTION OF Fe2O3/Al SYSTEM

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1413-1418
Author(s):  
JING ZHANG ◽  
HUASHUN YU ◽  
QI ZHAO ◽  
HAITAO WANG ◽  
GUANGHUI MIN
Keyword(s):  
Tensile Strength ◽  
Room Temperature ◽  
Matrix Alloy ◽  
Second Step ◽  
In Situ Reaction ◽  
Micron Size ◽  
The Matrix ◽  
Higher Temperature ◽  
Mechanism Of The Reaction

Al 2 O 3 particles reinforced ZL109 composite was prepared by in situ reaction between Fe 2 O 3 and Al . The phases were identified by XRD and the microstructures were observed by SEM and TEM. The Al 2 O 3 particles in sub-micron size distribute uniformly in the matrix and Fe displaced from the in situ reaction forms net-like alloy phases with Cu , Ni , Al , Mn ect. The hardness and the tensile strength at room temperature of the composites have a small increase compared with the matrix. However, the tensile strength at 350°C can reach 92.18 MPa, which is 18.87 MPa higher than that of the matrix. The mechanism of the reaction in the Fe 2 O 3/ Al system was studied by DSC. The reaction between Fe 2 O 3 and Al involves two steps. The first step in which Fe 2 O 3 reacts with Al to form FeO and Al 2 O 3 takes place at the matrix alloy melting temperature. The second step in which FeO reacts with Al to form Fe and Al 2 O 3 takes place at a higher temperature.

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