Using Recycled Materials for Semi- Solid Processing of Al-Si-Mg Based Alloys

2022 ◽  
Vol 327 ◽  
pp. 207-222
Author(s):  
Jiehua Li ◽  
Xun Zhang ◽  
Johannes Winklhofer ◽  
Stefan Griesebner ◽  
Bernd Oberdorfer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Shape Factor ◽  
Volume Fraction ◽  
Solidification Microstructure ◽  
Number Density ◽  
Foundry Industry ◽  
Transmission Electron ◽  
Eutectic Si ◽  
Semi Solid ◽  
Secondary Materials

In order to reduce CO2 emission and energy consumption, more recycled secondary materials have to be used in foundry industry, especially for Al-Si-Mg based alloys for semi-solid processing. In this paper, Al-Si-Mg based alloys with the addition of recycled secondary materials up to 30 % (10, 20, 30 %, respectively) have been produced by semi-solid processing. The solidification microstructure was investigated using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, computed tomography (CT) was also used to elucidate the size, size distribution, number density, volume fraction of porosities. It was found that with the addition of the recycled secondary materials up to 30 %, there is no significant effect on the solidification microstructure in terms of the grain size and the shape factor of primary α-Al and the second α-Al. More importantly, the morphology of eutectic Si can be well modified and that of the Fe-containing phase (π-AlSiMgFe) can be tailored. Furthermore, with increasing recycled secondary materials, at least another two important issues should also be highlighted. Firstly, more TiB2 particles were observed, which can be due to the addition of Al-Ti-B grain refiners for the grain refinement of recycled secondary materials. Secondly, a significant interaction between Sr and P was also observed in the recycled secondary materials. The present investigation clearly demonstrates that Al-Si-Mg based alloys with the addition of recycled secondary materials at least up to 30% can be used for semi-solid processing, which may facilitate better sustainability.

scholarly journals Influence of Thermal Aging Parameters on the Characteristics of Aluminum Semi-Solid Alloys

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 746 ◽  
Author(s):  
Khaled Ragab ◽  
Mohamed Bouazara ◽  
Xiao Chen
Keyword(s):  
Electron Microscopy ◽  
Aluminum Alloys ◽  
Thermal Aging ◽  
Aging Treatment ◽  
Load Variations ◽  
Transmission Electron ◽  
Semisolid Alloys ◽  
Automotive Parts ◽  
Semi Solid ◽  
Solid Alloys

The current study aimed at analyzing the response of semisolid A357 aluminum alloys to unconventional thermal treatment cycles of T4/T6/T7 conditions. The mechanical, electrical, and microstructural characterizations of such semisolid alloys were investigated. The microstructure evolutions of Fe-intermetallic phases and strengthening precipitates were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The mechanical failure of such semi solid A357 aluminum alloys, used for suspension automotive parts, is mostly related to cracking issues which start from the surface due to hardness problems and propagate due to severe load variations. For these reasons, the multiple thermal aging cycles, in this study, are applied to enhance the mechanical properties and to have compromised values compared to those obtained by standard thermal treatments. The results obtained in this work indicate that the heat treatment of this alloy can be optimized. The results showed that the optimum characteristics of A357 semisolid alloys were obtained by applying thermal under-aging cycle, interrupted thermal aging cycles and a T7/T6 two steps aging treatment condition. The electrical conductivity and electron microscopy were applied in this study to analyze the characteristics of hardening phases formed due to different aging cycles applied to the alloys investigated.

The influence of Pt and SrTiO3 interlayers on the microstructure of PbTiO3 thin films deposited by laser ablation on (001) MgO

1995 ◽  
Vol 10 (4) ◽  
pp. 791-794 ◽  
Author(s):  
S. Stemmer ◽  
S.K. Streiffer ◽  
W-Y. Hsu ◽  
F. Ernst ◽  
R. Raj ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Laser Ablation ◽  
Volume Fraction ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Transmission Electron ◽  
Electrical Conductivities ◽  
Different Types ◽  
Oriented Material

We have used conventional and high-resolution transmission electron microscopy to investigate the microstruture of epitaxial, ferroelectric PbTiO3 films grown by pulsed laser ablation on (001) MgO single crystals, and on MgO covered with epitaxial Pt or SrTiO3. Pronounced variations are found in the widths and lengths of a-axis-oriented domains in these films, although the volume fraction of a-axis-oriented material varies only weakly for the different types of samples. In addition, the films deposited onto Pt-coated MgO have a larger grain size than those deposited onto bare MgO or SrTiO3/MgO. Possible reasons for the variations in the distribution of a-axis-oriented material in these samples include differences in the elastic properties and electrical conductivities of the different substrate combinations.

Effects of Cooling Rate on Morphology of Eutectic Si in RE Modified Al-10wt.%Si Alloy

2016 ◽  
Vol 850 ◽  
pp. 587-593 ◽  
Author(s):  
Wen Yi Liu ◽  
Cong Xu ◽  
Wen Long Xiao ◽  
Mao Wen Liu ◽  
Jian Bin Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cooling Rate ◽  
Morphology Evolution ◽  
Fiber Modification ◽  
Transmission Electron ◽  
Fiber Size ◽  
Eutectic Si ◽  
Scanning Electron

Morphology evolution of eutectic Si in Ce-rich mischmetal (RE) modified Al-10wt.%Si alloy at different cooling rates was investigated. The morphology of eutectic Si and modification mechanism of RE was investigated by scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The results showed that the RE modified eutectic Si exhibited a plate-like morphology under the low cooling rate (~100K/s). When cooling rate increased to ~600K/s, some branches were observed on the eutectic Si. In the RE modified alloy with a higher cooling rate (~1000K/s), the number of the branches on RE modified eutectic Si increased, and the morphology of eutectic S was modified to coral-like structure. The addition of Sr caused a flake-to-fiber modification of eutectic Si at low cooling rate, and the fiber size decreased with cooling rate increasing. The morphological observations indicated that the morphology of eutectic Si in RE modified alloy was significantly influenced by the cooling rate, while the modification efficiency of RE was lower than that of Sr.

Preparation and Property of Al87Ce3Ni8.5Mn1.5 Nanophase Amorphous Composites

2011 ◽  
Vol 412 ◽  
pp. 263-266
Author(s):  
Hong Wei Zhang ◽  
Li Li Zhang ◽  
Feng Rui Zhai ◽  
Jia Jin Tian ◽  
Can Bang Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
Volume Fraction ◽  
Material Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures

The higher mechanical strength of Al87Ce3Ni8.5Mn1.5 nanophase amorphous composites has been obtained with two methods. The first nanophase amorphous composites are directly produced by the single roller spin quenching technology. The method taken for the second nanophase amorphous composites is at first to obtain amorphous single-phase alloy, followed by annealed at different temperatures .The formative condition, the microstructure, the particle size, the volume fraction of α-Al phase and microhardness of nanophase amorphous composites etc have been investigated and compared by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The microstructure of composites produced by the second method is higher than the former, the fabricated material structure of the system is more uniform and the process is easier to control.

scholarly journals Thickening of T1 Precipitates during Aging of a High Purity Al–4Cu–1Li–0.25Mn Alloy

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 30 ◽  
Author(s):  
Ines Häusler ◽  
Reza Kamachali ◽  
Walid Hetaba ◽  
Birgit Skrotzki
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Purity ◽  
External Load ◽  
Volume Fraction ◽  
Single Layer ◽  
Age Hardening ◽  
Defect Type ◽  
Transmission Electron

The age hardening response of a high-purity Al–4Cu–1Li–0.25Mn alloy (wt. %) during isothermal aging without and with an applied external load was investigated. Plate shaped nanometer size T1 (Al2CuLi) and θ′ (Al2Cu) hardening phases were formed. The precipitates were analyzed with respect to the development of their structure, size, number density, volume fraction and associated transformation strains by conducting transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) studies in combination with geometrical phase analysis (GPA). Special attention was paid to the thickening of T1 phase. Two elementary types of single-layer T1 precipitate, one with a Li-rich (Type 1) and another with an Al-rich (Defect Type 1) central layer, were identified. The results show that the Defect Type 1 structure can act as a precursor for the Type 1 structure. The thickening of T1 precipitates occurs by alternative stacking of these two elementary structures. The thickening mechanism was analyzed based on the magnitude of strain associated with the precipitation transformation normal to its habit plane. Long-term aging and aging under load resulted in thicker and structurally defected T1 precipitates. Several types of defected precipitates were characterized and discussed. For θ′ precipitates, a ledge mechanism of thickening was observed. Compared to the normal aging, an external load applied to the peak aged state leads to small variations in the average sizes and volume fractions of the precipitates.

Solidification and Microstructure Control of Mg-rich Alloys in the Mg-Zn-Y Ternary Systemya

2000 ◽  
Vol 643 ◽  
Author(s):  
E.S. Park ◽  
S. Yi ◽  
J.B. Ok ◽  
D.H. Bae ◽  
W.T. Kim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Volume Fraction ◽  
Eutectic Reaction ◽  
Primary Crystallization ◽  
Icosahedral Phase ◽  
Orientation Relationships ◽  
Transmission Electron ◽  
Mg Content ◽  
Solidification Microstructures ◽  
Scanning Electron

AbstractSolidification microstructures of Mg rich Mg-Zn-Y alloys were studied by using optical microscopy, scanning electron microscopy and transmission electron microscopy. Pseudo eutectic reaction (Liquid→α-Mg + icosahedral phase) takes place during solidification. Alloys containing high Mg content solidifies by primary crystallization ofα-Mg followed by the eutectic reaction at interdendritic region. Mg68Zn28Y4 alloy solidifies by primary crystallization of I-phase followed by theeutectic reaction into a mixture of α-Mg and I-phase. Occasionally D-phase and Mg4Zn7 phases were observed to form with orientation relationships with previously formed I-phase and D-phase, respectively. Thestrength of the alloys increased with increasing the volume fraction of I-phase.

Coarsening Process of Decomposed Phases in Cu-Ni-Cr Alloys

2010 ◽  
Vol 654-656 ◽  
pp. 2346-2349
Author(s):  
Felipe Hernandez-Santiago ◽  
Victor M. Lopez-Hirata ◽  
Maribel L. Saucedo-Muñoz
Keyword(s):  
Electron Microscopy ◽  
Activation Energy ◽  
Volume Fraction ◽  
Ternary Alloys ◽  
Size Distributions ◽  
Rich Phase ◽  
Thermally Activated ◽  
Ternary Alloy Systems ◽  
Transmission Electron ◽  
Lsw Theory

A study of the coarsening process of the decomposed phases was carried out in the Cu-34wt.%Ni-4wt.%Cr and Cu-45wt.%Ni-10wt.%Cr alloys using transmission electron microscopy. As aging progressed, the morphology of the coherent decomposed Ni-rich phase changed from cuboids to platelets aligned in the <100> Cu-rich matrix directions. Prolonged aging caused the loss of coherency between the decomposed phases and the morphology of the Ni-rich phase changed to ellipsoidal. The variation of mean radius of the coherent decomposed phases with aging time followed the modified LSW theory for thermally activated growth in ternary alloy systems. The coarsening rate was faster in the symmetrical Cu-45wt.%Ni-10wt.%Cr alloy due to its higher volume fraction of precipitates. The activation energy for thermally activated growth was determined to be about 182 and 102 kJ mol-1 in the Cu-34wt.%Ni-4wt.%Cr and Cu-45wt.%Ni-10wt.%Cr alloys, respectively. The size distributions of precipitates in the Cu-Ni-Cr alloys were broader and more symmetric than that predicted by the modified LSW theory for ternary alloys.

Diffusion Process Of Interstitial Atoms In Inp Studied By Transmission Electron Microscopy

1996 ◽  
Vol 442 ◽  
Author(s):  
Y. Ohno ◽  
S. Takeda ◽  
M. Hirata
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Diffusion Process ◽  
Annealing Temperature ◽  
Number Density ◽  
Electron Dose ◽  
Final Density ◽  
Maximum Value ◽  
Transmission Electron ◽  
Interstitial Atoms

AbstractIt is found that interstitial agglomerates are formed uniformly in an irradiated area of InP by annealing at the temperature above 700 K after 200 keV-electron irradiation. TEM observation shows that the number density of interstitial atoms in the agglomerates reached a maximum value when the growth of all the agglomerates stopped. The final density did not depend on annealing temperature but on electron dose, and it increased quadratically with electron dose up to 2×1022 cm−2. In order to explain the experimental results, we have proposed a new model that the agglomerates are formed by thermal diffusion and agglomeration of interstitial-pairs, i.e. Ini-Pi interstitial-pairs. From the analysis, the migration energies for the pairs are estimated to be 1.52 eV. The onset temperature for the diffusion of the pairs is estimated as 550 K.

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