Investigation of the effect of solidification rate on microstructure of Al-0.13Si-0.3Fe DC-cast alloy using EBSD and DSC techniques

2020 ◽  
Vol 111 (11) ◽  
pp. 931-937
Author(s):  
Ehab Elsharkawi ◽  
Donald MacNeil ◽  
Hatem Mrad ◽  
X. Grant Chenc
Keyword(s):  
Quantitative Methods ◽  
Volume Fraction ◽  
Cast Alloy ◽  
Solidification Rate ◽  
Intermetallic Phase ◽  
Intermetallic Phases ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Scanning Calorimetry ◽  
Iron Intermetallic

Abstract Direct chill (DC) casting is used to cast aluminum alloy ingots. Casting speed influences the distribution and types of iron intermetallics in aluminum ingot microstructure. This study attempted to identify and quantify the iron intermetallic phases in the microstructure of laboratory scale DC Al- 0.13Si-0.3Fe samples using differential scanning calorimetry, scanning electron microscopy, electron backscatter diffraction, and energy dispersive X-ray spectroscopy. Both stable and non-stable iron intermetallic phases were observed but to different extents in all alloy samples’ microstructure. Two different types of iron-rich, AlFeSi globular particles were observed in the alloy samples’ microstructure. As a result, an attempt was made to understand the formation temperature and composition of these small, globular particles. DSC results confirmed that the enthalpy change of phase formation is dependent mainly on the volume fraction of the iron intermetallic phase in the microstructure. A good agreement was observed between the quantitative analysis results and the DSC analysis, which supports the reliability of the quantitative methods used in this study. The results obtained in this study bridge existing gaps in literature on the effect of cooling rate on the selection of iron intermetallic phases, in general, and in the AlSiFe globular particles, in particular.

The Study of Iron Intermetallic Phases Morphology with Applying Deep Etching in Secondary Al-Si Alloys

2014 ◽  
Vol 782 ◽  
pp. 359-364 ◽  
Author(s):  
Lenka Hurtalová ◽  
Eva Tillová ◽  
Mária Chalupová
Keyword(s):  
Mechanical Properties ◽  
Alloy Composition ◽  
Cast Alloy ◽  
Intermetallic Phase ◽  
Three Dimensional ◽  
Intermetallic Phases ◽  
Rail Vehicles ◽  
Structure Improvement ◽  
Second Phases ◽  
Iron Intermetallic

The morphology control of intermetallic phases is very important in secondary aluminium cast alloy, because these alloys contain more of additional elements, which forms various intermetallic phases in the structure. Improvement of the mechanical properties is strongly depending upon the morphology, type and distribution of the second phases, which are in turn a function of the alloy composition and cooling rate. The iron intermetallic phase has the greatest influence on mechanical properties. It is necessary to study microstructure of Al-Si alloys, because the metallographic evaluation of aluminium alloys is not simple and these alloys are used for production many mechanical components, especially for cars, aerospace and rail vehicles. The study of iron intermetallic phases was performed using light microscope Neophot 32 and SEM observation with EDX analysis. For study the morphology of these phases were samples deep-etched for 30 s in HCl solution, in order to reveal the three-dimensional morphology of the iron phases.

scholarly journals Formation of intermetallic phases during solidification in Al-Mg-Mn 5xxx alloys with various Mg levels

2020 ◽  
Vol 326 ◽  
pp. 02002
Author(s):  
Ahmed Y. Algendy ◽  
Kun Liu ◽  
X.-Grant Chen
Keyword(s):  
Intermetallic Phase ◽  
Intermetallic Phases ◽  
Chinese Script ◽  
Electron Backscattered Diffraction ◽  
Scanning Calorimetry ◽  
Scheil Simulation ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Mg Content ◽  
Dominant Phase

In the present study, four Al-Mg-Mn 5xxx alloys with different Mg levels (2-5 wt.%) were investigated for better understanding the evolution of intermetallic phases formed during solidification. Optical and scanning electron microscopes, electron backscattered diffraction and differential scanning calorimetry analyses in combination with thermodynamic calculation were used to identify various intermetallic phases. Results showed that the most dominant intermetallic phases are Al6(Mn,Fe), α-Al(Fe,Mn)Si, Al3Fe, Alm(Mn,Fe) and Mg2Si in experimental Al-Mg-Mn alloys, which is greatly dependant on the Mg levels. It is found that Chinese script α-Al(Fe,Mn)Si is the dominant iron-rich intermetallic phase for the alloys containing 2-3 wt.% Mg, while blocky Al6(Mn,Fe) and needle-like Al3(Mn,Fe) become the major phases for the alloy containing 4 wt.% Mg. Further increasing Mg content to 5 wt. %, the dominant phase transfers to blocky Al6(Mn,Fe) intermetallic. Meanwhile, the morphology of primary Mg2Si is changed from well-branched to plate-like with increasing Mg contents. In addition, β-Al3Mg2 and τ-Al6CuMg4 eutectic phases have been observed in the alloys with 3-5 wt. % Mg. A comparison on various intermetallic phases from the Scheil simulation and the actual as-cast microstructure is provided.

Influence of Aging Temperatures and Times on Mechanical Properties of Vacuum High Pressure Die Cast Aluminum Alloy A356

2012 ◽  
Vol 445 ◽  
pp. 277-282 ◽  
Author(s):  
Xue Zhi Zhang ◽  
Kazi Ahmmed ◽  
Meng Wang ◽  
Henry Hu
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Thermal Treatment ◽  
Tensile Properties ◽  
Intermetallic Phase ◽  
Aged Alloy ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Die Cast ◽  
Wide Range

In this study a number of thermal treatment schemes over a wide range of temperatures between 120˚ to 350˚ C and times (30 120 minutes) have been experimented in an effort to understand the effect of thermal treatment on tensile properties of vacuum die cast modified aluminum alloy A356. The results show that, the morphology of eutectic silicon has a sound effect on the tensile properties of the tested alloy. The content of magnesium-based intermetallic phases, their morphology and distribution throughout the matrix affect the mechanical properties of the aged alloy as well. The reduction in the strengths of the alloy treated at 350°C for two hours should be at least attributed partly to the absence of the magnesium-based intermetallic phase. However the presence of sufficient amount of magnesium intermetallic phase had played important role in strengthening the alloy thermally treated at 200°C for 90 minutes.

scholarly journals Microstructure as an essential aspect of EN AW 7075 aluminum alloy quality influenced by electromagnetic field during continuous casting process

2021 ◽  
Vol 75 (1) ◽  
pp. 31-37
Author(s):  
Aleksandra Pataric ◽  
Marija Mihailovic ◽  
Branislav Markovic ◽  
Miroslav Sokic ◽  
Andreja Radovanovic ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Electromagnetic Field ◽  
Aluminum Alloy ◽  
Continuous Casting ◽  
Cast Alloy ◽  
Casting Process ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Continuous Casting Process

Microstructure assessment is crucial for the design and production of high-quality alloys such as cast aluminum alloy ingots. Along with the effect of a more homogeneous microstructure to result in much better mechanical properties, better as-cast alloy quality indicates a higher efficiency of the aluminum alloys production process. During the aluminum alloy solidification process many microstructural defects can occur, which deteriorate the mechanical properties and hence decrease the usability of such an ingot. Application of the electromagnetic field during the vertical continuous casting process significantly reduces occurrence of these defects. In the present study, EN AW 7075 alloy samples were cast with and without application of an electromagnetic field and examined regarding the microstructure, electrical conductivity, and changes in the phase composition. The obtained results clearly show that it is possible to decrease or avoid casting defects by the electromagnetic field application as verified by the microstructure characterization and quantification, electrical conductivity tests and differential thermal analysis (DTA).

Processing, Microstructure and Properties of Laminated Ni-Intermetallic Composites Synthesised Using Ni Sheets and Al Foils

2011 ◽  
Vol 56 (3) ◽  
pp. 693-702 ◽  
Author(s):  
M. Konieczny ◽  
R. Mola ◽  
P. Thomas ◽  
M. Kopciał
Keyword(s):  
Microprobe Analysis ◽  
Volume Fraction ◽  
Laminated Composites ◽  
Intermetallic Phase ◽  
Intermetallic Phases ◽  
Solid State Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructure And Properties ◽  
Final Microstructure

Processing, Microstructure and Properties of Laminated Ni-Intermetallic Composites Synthesised Using Ni Sheets and Al FoilsThe laminated Ni-(NiAl3+Ni2Al3) and Ni-Ni2Al3intermetallic composites were fabricated by reaction synthesis in vacuum using Ni sheets and Al foils. The aluminium layers were completely consumed due to the formation of intermetallic phases. The Ni-Al reaction at 620°C was studied by interrupting in steps the reaction process to observe the microstructural changes. The final microstructure consisted of alternating layers of intermetallic phases and unreacted nickel can be designed easily because the stable structures of the composites depend only on the treating time. Microstructural examinations using scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray microprobe analysis (EDX) demonstrated that after 1h of treatment Ni2Al3is the predominant intermetallic phase. The formation of the Ni2Al3phase is thermodynamically favoured over the formation of the other phases and can be understood from the steps occurred through a series of solid state reactions. The tensile strength of the laminated composites increases with an increase of the volume fraction of the intermetallic products. However, it decreases after long heat treatment because the Ni2Al3/Ni2Al3interfaces can very easily delaminate due to a very weak bonding caused by continuous Al2O3inclusions. Observations show that the laminated composites exhibit a mixture of brittle fracture of intermetallics and ductile one of residual Ni layers.

scholarly journals The Effect of Y/Er and Zn Addition on the Microstructure and Mechanical Properties of Mg-11Li Alloy

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3066 ◽  
Author(s):  
Mingquan Zhang ◽  
Jinghuai Zhang ◽  
Ruizhi Wu ◽  
Hongwei Cui ◽  
Ertuan Zhao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fine Particles ◽  
Cast Alloy ◽  
Intermetallic Phase ◽  
Intermetallic Phases ◽  
Face Centered Cubic ◽  
Hexagonal Close Packed ◽  
Intermetallic Particles ◽  
Zn Addition ◽  
Face Centered

Although body-centered cubic (BCC) structural magnesium–lithium (Mg-Li) alloys have lower density and better formability than common hexagonal close-packed (HCP) Mg alloys, their applications remain limited due to their low strength. The purpose of this study is to investigate the effect of Y/Er and Zn addition on the microstructure and tensile properties of Mg-11Li alloy with a BCC structural matrix by comparing Mg-11Li, Mg-11Li-4Y-2Er-2Zn, and Mg-11Li-8Y-4Er-4Zn (wt %) alloys. The results indicate that the addition of Y/Er and Zn at a ratio of 3:1 cannot promote the formation of long-period stacking ordered structure in Mg-11Li alloy such as that in Mg-Y-Er-Zn alloys and the dominant intermetallic phases formed are BCC Mg24RE5 and face-centered cubic (FCC) Mg3RE2Zn3 phases. With an increase of the content of Y/Er and Zn in an as-cast alloy, the fraction of intermetallic particles increases and the grain size decreases. The addition of Y/Er, as well as Zn, dramatically promotes the refinement of dynamic recrystallization (DRX) during extrusion. The initial intermetallic phases induced by Y/Er and Zn addition are broken into relatively fine particles during extrusion, and this contributes to refining the dynamic recrystallized (DRXed) grains mainly by the particle stimulated nucleation mechanism. The as-extruded Mg-11Li-4Y-2Er-2Zn and Mg-11Li-8Y-4Er-4Zn alloys exhibit much higher tensile strength as compared with as-extruded Mg-11Li alloy, which is mainly ascribed to the refined DRXed grains and numerous dispersed intermetallic phase particles. It is suggested that further refinement of intermetallic particles in these extruded Mg-11Li-based alloys may lead to higher quality alloy materials with low density and excellent mechanical properties.

Metallographic Characterization of Porosity in A Cast Aluminum Alloy A356-T6

2007 ◽  
Vol 546-549 ◽  
pp. 989-994 ◽  
Author(s):  
Guang Ran ◽  
Jing En Zhou
Keyword(s):  
Aluminum Alloy ◽  
Cast Alloy ◽  
Area Fraction ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Maximum Area ◽  
Secondary Dendrite Arm Spacing ◽  
Pore Area ◽  
Area Percentage

Microporosity in both HIPped and non-HIPped unmodified aluminum cast alloy A356-T6 was quantified metallographically in terms of its area, area percentage, length, sphericity and perimeter. In the studied materials, the secondary dendrite arm spacing (SDAS) values vary from 82μm to 96μm for both the HIPped and the non-HIPped castings. HIPping process significantly reduces porosity area fraction and pore sizes. The maximum area fraction of porosity and maximum pore area of the non-HIPped specimens are increased with increasing SDAS.

Micro-Structural Evolution of AlCu5MnCdVA Cast Aluminum Alloy by Semi-Solid Isothermal Annealing Process

2007 ◽  
Vol 26-28 ◽  
pp. 489-493
Author(s):  
Guang Yu Yang ◽  
Wan Qi Jie ◽  
Qi Tang Hao ◽  
Run Qiang Zhang
Keyword(s):  
Aluminum Alloy ◽  
Cast Alloy ◽  
Isothermal Holding ◽  
Structural Evolution ◽  
Average Diameter ◽  
Rate Variation ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Semi Solid ◽  
Holding Temperature

Isothermal grain coarsening of AlCu5MnCdVA aluminum alloy prepared by permanent mould casting during semi-solid treatment process was studied. It was found that the relationship between the average diameter of α (Al) grains and the isothermal holding time fitted the formula r − r = K ⋅ t − − ' 3 0 3 , where the coarsening rate K’ varied with the holding temperature, which equaled to 4.288×10-10m3/s and 5.962×10-10m3/s at the holding temperature. A modified model of liquid film migration has been proposed for explaining of 622°C and 631°C respectively the coarsening rate variation with annealing temperature. The diffusion of the solutes as well as vacancies, and the grain boundary tension are responsible for the microstructure evolution of AlCu5MnCdVA cast alloy.

scholarly journals Precipitation Kinetics and Evaluation of the Interfacial Mobility of Precipitates in an AlSi7Cu3.5Mg0.15 Cast Alloy with Zr and V Additions

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 777 ◽  
Author(s):  
Pierre Heugue ◽  
Daniel Larouche ◽  
Francis Breton ◽  
Denis Massinon ◽  
Rémi Martinez ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Cast Alloy ◽  
Specific Power ◽  
Cast Aluminum ◽  
Precipitation Kinetics ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Cast Aluminum Alloys ◽  
Transmission Electron ◽  
Interfacial Mobility

Recent environmental restrictions constrained car manufacturers to promote cast aluminum alloys working at high temperatures (180 °C–300 °C). The development of new alloys permits the fabrication of higher-strength components in engine downsizing. Those technologies increase internal loadings and specific power and stretch current materials to their limits. Transition metals in aluminum alloys are good candidates to improve physical, mechanical, and thermodynamic properties with the aim of increasing service life of parts. This study is focused on the modified AlSi7Cu3.5Mg0.15 alloy where Mn, Zr, and V have been added as alloying elements for high-temperature applications. The characterization of the cast alloy in this study helps to evaluate and understand its performance according to their physical state: As-cast, as-quenched, or artificially aged. The precipitation kinetics of the AlSi7Cu3.5Mg0.15 (Mn, Zr, V) alloy has been characterized by differential scanning calorimetry (DSC), transmission electron microscopy (TEM) observations, and micro-hardness testing. The Kissinger analysis was applied to extract activation energies from non-isothermal DSC runs conducted at different stationary heating rates. Finally, first-order evaluations of the interfacial mobility of precipitates were obtained.

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