Observation of large Equilibrium Phase of Al-Mg-Si Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 977-980
Author(s):  
Shintaro Hida ◽  
Šárka Mikmeková ◽  
Kenji Matsuda ◽  
Susumu Ikeno
Keyword(s):  
Solid Solution ◽  
Orientation Relationship ◽  
Supersaturated Solid Solution ◽  
Metastable Phase ◽  
Equilibrium Phase ◽  
Precipitation Sequence ◽  
Hexagonal Plate ◽  
Β Phase ◽  
Hexagonal Shape ◽  
Al Matrix

The precipitation sequence in Al-Mg-Si alloy is generally accepted as supersaturated solid solution GP-zone β β β (Mg2Si). The effect of Ag or Cu in Al-Mg-Si alloy was reported in our previous work. There is little report about effect of Ag or Cu on the metastable phase and equilibrium phase in this alloy the system. Hexagonal plate like β-phase and Q-phase were observed the Cu added alloy. This hexagonal-shaped β-phase has unique orientation relationship to the Al matrix. This work was performed to compare the shape of effect of the additional elements on the equilibrium phase. The hexagonal shape precipitate was observed in Cu or Ag added alloys aged at 673K.

scholarly journals Precipitation sequence of an aged Al-Mg-Si alloy

2010 ◽  
Vol 46 (2) ◽  
pp. 171-180 ◽  
Author(s):  
X. Fang ◽  
M. Song ◽  
K. Li ◽  
Y. Du
Keyword(s):  
Solid Solution ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Supersaturated Solid Solution ◽  
Metastable Phase ◽  
Stable Phase ◽  
Precipitation Sequence ◽  
Maximum Hardness ◽  
Strengthening Phase ◽  
Transmission Electron

Heat treatable Al-Mg-Si alloys can be strengthened via the precipitation of metastable phase particles. The precipitation sequence of an Al-0.89Mg-0.75Si alloy with trace Fe and Zn elements during aging at 180 ?C has been investigated by transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM) and hardness measurements. It has been shown that the precipitation sequence of the alloy can be identified as follows: supersaturated solid solution ? G.P. zones ? metastable ?? precipitates ? metastable ?? precipitates ? stable ? phase + Si particles. It is indicated that ?? phase remains stable up to 30 hours at 180?C. The hardness measurements during aging realize that the main strengthening phase for the investigated Al-Mg-Si alloy is ?? precipitates and the maximum hardness is obtained after aging at 180 ?C for 4~6.5 hours.

scholarly journals Formation of Intermediate Phases and Supersaturated Solid Solution in Al-Cu System during Diffusion

2018 ◽  
Vol 383 ◽  
pp. 31-35 ◽  
Author(s):  
Alexey Rodin ◽  
Nataliya Goreslavets
Keyword(s):  
Phase Diagram ◽  
Solid Solution ◽  
High Temperature ◽  
Chemical Composition ◽  
Low Temperature ◽  
Supersaturated Solid Solution ◽  
Diffusion Processes ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Intermediate Phases

The study of diffusion processes in the aluminum - copper system was carried out at the temperature 350 and 520 °C. Special attention was paid on the chemical composition of the system near Al/Cu interface. It was determined that the intermediate phases in the system, corresponding to the equilibrium phase diagram, were not formed at low temperature. At high temperature the intermediate phases forms starting with Cu - rich phases. In both cases supersaturated solid solution of copper in aluminum could be observed near the interface.

Study on the Precipitation Sequence of Aged NCu30-4-2-1 Alloy by DSC

2014 ◽  
Vol 1061-1062 ◽  
pp. 35-38
Author(s):  
Yun Long Ai ◽  
Xiao Rui Shen ◽  
Wei Hua Chen ◽  
Yao Hui Xie
Keyword(s):  
Solid Solution ◽  
Differential Scanning Calorimetry ◽  
Supersaturated Solid Solution ◽  
Aging Treatment ◽  
Holding Time ◽  
Precipitation Sequence ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Different Temperatures ◽  
Block Distribution

NCu30-4-2-1 alloy was handled by solid solution at 950°Cfor 2h and then taking aging treatment at different temperatures and holding time. The microstructural evolution of NCu30-4-2-1 alloy in the process of aging treatment was investigated by metallographic microscope, X-ray diffractometer and differential scanning calorimetry. The results show that the phases of as-cast NCu30-4-2-1 alloy is composed by dendritic α-Ni-based solid solution and β-Ni3Si. After solid solution and aging treatment, the block distribution β-Ni3Si dissolves and many small granular dispersed distribution β'-Ni3Si precipitate out. With the increase of aging temperature and holding time, metastable β' tends to transform into stable β-Ni3Si. The precipitation sequence of aged NCu30-4-2-1alloy is supersaturated solid solution of α-Ni, GP zone, β'-Ni3Si and β-Ni3Si.

TEM Observation for Precipitates Structure of Al-1.0Mass%Mg2Ge Alloys Aged at 473K

2014 ◽  
Vol 794-796 ◽  
pp. 992-995
Author(s):  
Akihiro Kawai ◽  
Keisuke Matsuura ◽  
Katsumi Watanabe ◽  
Kenji Matsuda ◽  
Susumu Ikeno
Keyword(s):  
Phase Diagram ◽  
Equilibrium Phase ◽  
Hardness Test ◽  
Age Hardening ◽  
Precipitation Sequence ◽  
Hardening Behavior ◽  
Β Phase ◽  
Hrtem Observation ◽  
Peak Aged ◽  
First Time

It is known that Al-Mg-Ge alloys show a similar precipitation sequence to that of Al-Mg-Si alloys, and that ther equilibrium phase is β-Mg2Ge according to the phase diagram. In this study, the precipitation sequence and age-hardening behavior of Al-1.0mass%Mg2Ge alloys has been investigated by hardness test, write out in full first time used TEM and HRTEM observations on.The hardness curves showed no big difference between peak values hardness for samples aged at 423, 473 and 523K. The precipitates in the peak-aged samples have been classified as some metastable phases, such as the β’-phase and parallelogram-type precipitates by HRTEM observation. The large precipitates are similar to the A-type precipitate in the Al-Mg-Si alloy with excess Si.

The Effect of Ag-Addition on Precipitation Sequence in Al-1.0mass%Mg2Si-Excess 0.4mass%Si Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 239-242 ◽  
Author(s):  
Kenji Niwa ◽  
Kenji Matsuda ◽  
Junya Nakamura ◽  
Tatsuo Sato ◽  
Susumu Ikeno
Keyword(s):  
Metastable Phase ◽  
Type A ◽  
Precipitation Sequence ◽  
Type B ◽  
X Ray ◽  
Β Phase ◽  
Transmission Electron ◽  
Alloy Type ◽  
Type C ◽  
Study Type

It is well known that Ag additional Al-1.0mass%Mg2Si-excess0.4mass%Si alloy (ex. Si-Ag alloy) has higher hardness and elongation than those of Al-1.0mass%Mg2Si-excess 0.4mass%Si alloy (ex. Si alloy). However, precipitation sequence of ex. Si-Ag alloy is not clear yet. In this work, precipitation sequence of ex. Si-Ag alloy has been investigated using high resolution transmission electron microscopy and X-ray energy dispersive spectroscopy. Precipitates were classified into several kinds by HRTEM images and SAED patterns, and relative frequencies of precipitates were also investigated. Its precipitation sequence was compared with that of ex. Si alloy. Type-A, Type-B and Type-C precipitates as special metastable phase in excess Si type Al-Mg-Si alloy, has been observed in ex. Si-Ag alloy, but β’ phase increased and Type-A and Type-B precipitate decreased in this study. Type-A precipitate was found at only grain boundary.

Metastable Phase Transformations in Ti-40Al-10V Alloy

1994 ◽  
Vol 364 ◽  
Author(s):  
G. Shao ◽  
P. Tsakiropoulos ◽  
A. P. Miodownik
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
Volume Fraction ◽  
Metastable Phase ◽  
Equilibrium Phase ◽  
Rapid Quenching ◽  
Β Phase ◽  
Transformation Sequence ◽  
Melt Spun ◽  
Melt Spun Ribbons

AbstractThe microstructures in arc melted ingots and melt spun ribbons have been investigated by electron microscopy and thermodynamic modelling has been used to study the phase transformations. In the ingot, solidification starts with the bcc β phase and at room temperature the structure consists of B2, ωordered, γ and α2 phases. The calculated equilibrium phase transformation sequence during cooling is L → L+ β→β→β + α→β2+α → α+β2+γ → α2+γ + B2. The phase transformation sequence is dramatically changed by rapid quenching from the melt. Athermal ordered w phase is formed in metastable B2 and the α→α2 ordering process is completely suppressed in the melt spun ribbons. The volume fraction of the α precipitates is also dependent on cooling rates.

On the Precipitation Behavior at 250 and 300 °C of WE54 Supersaturated Solid Solution

2012 ◽  
Vol 629 ◽  
pp. 85-89 ◽  
Author(s):  
S. Tighiouaret ◽  
H. Azzeddine ◽  
A. Sam ◽  
A. Sari ◽  
B. Alili ◽  
...  
Keyword(s):  
Solid Solution ◽  
Supersaturated Solid Solution ◽  
Precipitation Sequence ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Precipitation Behavior ◽  
X Ray ◽  
The Mean ◽  
Kinetics Of

The current study seeks to further understand the precipitation sequence in a WE54 Mg alloy using in situ X-ray diffraction, micro-hardness and electrical resistivity during ageing at 250 and 300 °C. We show that the mean hardening effect is due to the precipitation of β' and β1metastable phases. The analysis of the kinetics of the precipitation shows that both phases nucleate at grain boundaries and within grains in the form of plates.

scholarly journals Non-Equilibrium Processing of Ni-Si Alloys at High Undercooling and High Cooling Rates

2014 ◽  
Vol 790-791 ◽  
pp. 22-27 ◽  
Author(s):  
Andrew M. Mullis ◽  
Lei Gang Cao ◽  
Robert F. Cochrane
Keyword(s):  
Metastable Phase ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Eutectic Structure ◽  
Eutectic Solidification ◽  
Drop Tube ◽  
High Undercooling ◽  
Cooling Rates ◽  
Β Phase ◽  
High Cooling Rates

Melt encasement (fluxing) and drop-tube techniques have been used to solidify a Ni-25 at.% Si alloy under conditions of high undercooling and high cooling rates respectively. During undercooling experiments a eutectic structure was observed, comprising alternating lamellae of single phase γ (Ni31Si12) and Ni-rich lamellae containing of a fine (200-400 nm) dispersion of β1-Ni3Si and α-Ni. This is contrary to the equilibrium phase diagram from which direct solidification to β-Ni3Si would be expected for undercoolings in excess of 53 K. Conversely, during drop-tube experiments a fine (50 nm) lamellar structure comprising alternating lamellae of the metastable phase Ni25Si9 and β1-Ni3Si is observed. This is also thought to be the result of primary eutectic solidification. Both observations would be consistent with the formation of the high temperature form of the β-phase (β2/β3) being suppressed from the melt.

Effects of Addition of Heavy Rare-Earth Elements on the Structures and Resistivities of Al Thin Films for TFT - LCD Interconnects

1996 ◽  
Vol 441 ◽  
Author(s):  
Shinji Takayama ◽  
Naganori Tsutsui ◽  
Zheng Zhudan
Keyword(s):  
Thin Films ◽  
Solid Solution ◽  
Rare Earth ◽  
High Temperature ◽  
Supersaturated Solid Solution ◽  
Film Surface ◽  
Heavy Rare Earth ◽  
Heavy Rare Earth Elements ◽  
Metallic Compounds ◽  
Al Matrix

AbstractThe addition of Ho or Er to Al thin films markedly suppresses the grain growth at high temperature (350 °C – 450 °C). However, different from the effect of adding elements of Y, La, Pr, Nd, Sm, Gd, and Dy, thermal defects of hillocks or whiskers start to appear on the film surface after annealing at 300 °C ( though depending on the content of added elements). It has been revealed that small amounts of metallic compounds of Al3RE (RE = Ho and Er) have been segregated in a supersaturated solid solution of the Al phase after annealing at 300 °C, and that a large amount of added impurities still remained in the Al matrix. The resistivity of Al1−xREx alloy thin films (RE = Ho or Er, x = 2 – 7 atomic %) was 5 – 7 μΩcm after annealing at 450 °C.

Aging Behavior of Al-Mg-Ge Alloys with Different Mg2Ge Contents

2011 ◽  
Vol 409 ◽  
pp. 63-66
Author(s):  
Tomoatsu Murakami ◽  
Kenji Matsuda ◽  
Takeshi Nagai ◽  
Junya Nakamura ◽  
Tokimasa Kawabata ◽  
...  
Keyword(s):  
Relative Frequency ◽  
Equilibrium Phase ◽  
Hardness Test ◽  
Age Hardening ◽  
Precipitation Sequence ◽  
Aging Behavior ◽  
Hardening Behavior ◽  
Β Phase ◽  
Hrtem Observation ◽  
Peak Aged

It is known that Al-Mg-Ge alloy shows the similar precipitation sequence to Al-Mg-Si alloy, and its equilibrium phase is β-Mg2Ge according to its phase diagram. In this study, the precipitation sequence of Al-Mg-Ge alloys containing different contents of Mg2Ge has been investigated by hardness test, TEM and HRTEM observation to understand the effect of Mg2Ge contents on age-hardening behavior of the alloys. The hardness of as-quenched and peak-aged samples have been improved by increasing Mg2Ge contents. The precipitates in the peak-aged samples have been classified into some metastable phases, such as the β’-phase and parallelogram-type precipitate by HRTEM observation. The relative frequency of these precipitates in the is has been changed with Mg2Ge contents.

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