scholarly journals Characterization of the Bonding Zone in AZ91/AlSi12 Bimetals Fabricated by Liquid-Solid Compound Casting Using Unmodified and Thermally Modified AlSi12 Alloy

2020 ◽  
Vol 66 (7-8) ◽  
pp. 439-448
Author(s):  
Renata Mola ◽  
Tomasz Bucki
Keyword(s):  
Intermetallic Phase ◽  
Eutectic Structure ◽  
Az91 Alloy ◽  
Uniform Structure ◽  
Eutectic Region ◽  
Cast Material ◽  
Solid Compound ◽  
Matrix Cracks ◽  
Compound Casting ◽  
Bonding Zone

Liquid-solid compound casting was used to produce two types of AZ91/AlSi12 joints. The magnesium alloy was the cast material poured onto a solid aluminium alloy insert with an unmodified or modified structure. The bonding zone obtained for the unmodified insert was not uniform in thickness. There was a eutectic region (Mg17Al12 + a solid solution of Al in Mg) in the area closest to the AZ91. The region adjacent to the AlSi12 had a non-uniform structure with partly reacted Si particles surrounded by the Mg2Si phase and agglomerates of Mg2Si particles unevenly distributed in the Mg-Al intermetallic phases matrix. Cracks were detected in this region. In the AZ91/AlSi12 joint produced with a thermally modified AlSi12 insert, the bonding zone was uniform in thickness. The region closest to the AZ91 alloy also had a eutectic structure. However, significant microstructural changes were reported in the region adjacent to the modified AlSi12 alloy. The microstructure of the region was uniform with no cracks; the fine Mg2Si particles were evenly distributed over the Mg-Al intermetallic phase matrix. The study revealed that in both cases the microhardness of the bonding zone was several times higher than those of the individual alloys; however, during indenter loading, the bonding zone fabricated from modified AlSi12 alloy was less prone to cracking.

scholarly journals Microstructure of the Bonding Zone Between AZ91 and AlSi17 Formed by Compound Casting

2017 ◽  
Vol 17 (1) ◽  
pp. 202-206 ◽  
Author(s):  
R. Mola ◽  
T. Bucki ◽  
A. Dziadoń
Keyword(s):  
Intermetallic Phase ◽  
Casting Process ◽  
Az91 Alloy ◽  
Atmospheric Conditions ◽  
Az91 Magnesium Alloy ◽  
Compound Casting ◽  
Az91 Magnesium ◽  
Alloy Microstructure ◽  
Bonding Zone ◽  
Steel Mould

AbstractThis paper discusses the joining of AZ91 magnesium alloy with AlSi17 aluminium alloy by compound casting. Molten AZ91 was cast at 650°C onto a solid AlSi17 insert placed in a steel mould under normal atmospheric conditions. Before casting, the mould with the insert inside was heated up to about 370°C. The bonding zone forming between the two alloys because of diffusion had a multiphase structure and a thickness of about 200 μm. The microstructure and composition of the bonding zone were analysed using optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The results indicate that the bonding zone adjacent to the AlSi17 alloy was composed of an Al3Mg2intermetallic phase with not fully consumed primary Si particles, surrounded by a rim of an Mg2Si intermetallic phase and fine Mg2Si particles. The bonding zone near the AZ91 alloy was composed of a eutectic (an Mg17Al12intermetallic phase and a solid solution of Al and Si in Mg). It was also found that the compound casting process slightly affected the AZ91 alloy microstructure; a thin layer adjacent to the bonding zone of the alloy was enriched with aluminium.

scholarly journals Microstructure and Mechanical Properties of Galvanized-45 Steel/AZ91D Bimetallic Material by Liquid-Solid Compound Casting

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1651 ◽  
Author(s):  
Jun Cheng ◽  
Jian-hua Zhao ◽  
Jin-yong Zhang ◽  
Yu Guo ◽  
Ke He ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Corrosion Current ◽  
Eutectic Structure ◽  
Galvanized Steel ◽  
X Ray Diffraction ◽  
Solid Compound ◽  
Metallurgical Bonding ◽  
Compound Casting ◽  
Bimetallic Material ◽  
Bimetallic Materials

A connection between hot-dip galvanized 45 steel and AZ91D was achieved by liquid-solid compound casting to achieve one material with a better mechanical performance and a light weight. The microstructure and properties of galvanized-steel/AZ91D bimetallic materials were investigated in this study. A scanning electron microscopy (SEM), an energy dispersive spectroscopy (EDS), and an X-ray diffraction (XRD) were applied to analyze the microstructure evolution and formation mechanism of the galvanized 45 steel/AZ91D interface zone which could be divided into three layers. Among three different layers, the layer close to AZ91D was composed of α-Mg and an eutectic structure (α-Mg + MgZn). The intermediate layer was comprised of an eutectic structure (α-Mg + MgZn), and the layer adjacent to 45 steel consisted of α-Mg and FeAl3. Furthermore, galvanized-45 steel/AZ91D bimetallic material had better shear strength than the bare-45 steel/AZ91D metallic material which can indicate that owing to the formation of metallurgical bonding, the adhesive strength of galvanized-steel and AZ91D was improved to 11.81 MPa. In addition, the fact that corrosion potential increased from −1.493 V to −1.143 V and corrosion current density changed from 3.015 × 10−5 A/cm2 to 1.34 × 10−7 A/cm2 implied that the corrosion resistance of galvanized-steel/AZ91D was much better than AZ91D.

scholarly journals EIS and corrosion behaviour of plasma sprayed layers of Al and AlCr6Fe2 on AZ91

2018 ◽  
Vol 62 (2) ◽  
pp. 33-44
Author(s):  
F. T. Kubatík ◽  
J. Stoulil ◽  
F. Lukáč ◽  
K. Stehlíková ◽  
P. Slepička
Keyword(s):  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Intermetallic Phase ◽  
Fold Increase ◽  
Eutectic Structure ◽  
Metallurgical Bonding ◽  
Magnesium Alloy Az91 ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Sprayed Coatings

Abstract This work presents the preparation of coatings of aluminium and AlCr6Fe2 alloy on magnesium alloy AZ91 with metallurgical bonding. Coatings were prepared by plasma spraying system WSP®-H 500. This metallurgical bond (sub-layer) is formed by an eutectic structure consisting of the intermetallic phase Mg17Al12 and the solid solution of magnesium and aluminium. In this work, the layers were studied using electrochemical impedance spectroscopy (EIS). It was shown that there is a several fold increase of the polarization resistance (Rcν) of plasma-sprayed coatings of aluminium and AlCr6Fe2 alloy, compared with uncoated AZ91 in borate buffer with pH 9.1.

Application of Electron Microscopy to Investigation of Corrosion of Mg-Al Alloys in Various Electrolyte Solutions

2015 ◽  
Vol 231 ◽  
pp. 41-47
Author(s):  
Bartosz Chmiela ◽  
Adrian Mościcki ◽  
Maria Sozańska
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Pressure ◽  
Corrosion Behaviour ◽  
Intermetallic Phase ◽  
Electrolyte Solutions ◽  
Magnesium Hydride ◽  
Al Alloys ◽  
Az91 Alloy ◽  
Nacl Solution ◽  
Hydrogen Trap

The Mg-Al alloys are the best-known and most commonly used magnesium alloys (especially AZ91 alloy). However, the AZ91 alloy offers insufficient corrosion resistance. Many investigations show that hydrogen is the main corrosive factor appearing during chemical reactions between magnesium and water in electrolyte solution. The main intermetallic phase in the AZ91alloy is the Mg17Al12 (β phase), which is a hydrogen trap. During corrosion, magnesium hydride forms inside the β phase, and this phase is brittle fractured when the inner stress caused by hydrogen pressure and expansion stress due to the formation of magnesium hydride is higher thanthe fracture strength. We examined the corrosion behaviour of AZ91 and AE44 magnesium alloysin 0.1M Na2SO4 solution and 3.5% NaCl solution. We analysed two Mg-Al alloys in order todetermine the various effects of hydrogen on these materials.

Inhomogeneous Microstructure and its Thermal Stability of AlSi10Mg Lattice Structure Manufactured via Laser Powder Bed Fusion

2021 ◽  
Vol 1016 ◽  
pp. 826-831
Author(s):  
Mu Lin Liu ◽  
Naoki Takata ◽  
Asuka Suzuki ◽  
Makoto Kobashi
Keyword(s):  
Lattice Structure ◽  
Intermetallic Phase ◽  
Eutectic Structure ◽  
Bottom Surface ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Cellular Microstructure ◽  
Eutectic Si ◽  
Inhomogeneous Microstructure

The inhomogeneous microstructure and its change by annealing for an AlSi10Mg lattice structure with a body-centered cubic unit cell additively manufactured via laser powder bed fusion (LPBF) were investigated. The as-built lattice structure exhibited a cellular microstructure consisting of a number of primary α-Al phases decorated with α-Al/Si eutectic structure. The developed microstructure varied depending on the locations of the node and strut parts of the lattice structure. At the location near the bottom surface of the node part, the cellular microstructure became coarser and more equiaxed than those at the location near the top surface. At the location near the bottom surface of the strut part, the columnar α-Al phases were often elongated along the direction of the strut part. After the annealing at 300 °C for 2 h, numerous Si particles finely precipitated within the primary α-Al phases and coarsening of the eutectic Si phases occurred. After the annealing at 530 °C for 6 h, the microstructural characteristics changed significantly. A significant coarsening of the Si particles and the formation of Fe-containing intermetallic phase (β-AlFeSi) with a plate-shaped morphology occurred. The microstructures became homogeneous in the whole area of the lattice structure annealed at 530 °C for 6 h.

Microstructure Evolution of Zn-Al Cladding Fabricated on AZ31 Magnesium Alloy

2014 ◽  
Vol 1004-1005 ◽  
pp. 154-157
Author(s):  
An Sun ◽  
Xiao Ming Sui ◽  
Hai Tao Li ◽  
Qiang Wang
Keyword(s):  
Solid Solution ◽  
Chemical Composition ◽  
Microstructure Evolution ◽  
Element Concentration ◽  
Transverse Section ◽  
Eutectic Structure ◽  
Al Alloys ◽  
Magnesium Atom ◽  
Evolution Phase ◽  
Bonding Zone

The surface of AZ31 magnesium substrate is coated by Zn-Al alloys using cast-penetrated cladding. The transverse section of alloy cladding is composed of cladding zone, diffusional zone, and bonding zone. The microstructure evolution, phase constitution, and chemical composition of the transition layer are studied. The experimental results exhibit cladding zone contained dendrite matrix and interdendritic eutectic structures. The plume eutectic structure and columnar eutectic structure are formed in diffusional zone and bonding zone, respectively. Zn and Al solid solutions gradually decrease and disappear owing to the diffusion of magnesium atom and the changes of magnesium element concentration. Mg7Zn3 phases are generated rapidly due to the interdiffusion of zinc and magnesium atoms rapidly in the diffusional zone and bonding zone. As Mg-Zn eutectic phases hinder the movement of Mg and Al atoms, the Mg-Al intermetallic compounds are eliminated completely. The microstructure is transformed into Mg solid solution and Mg7Zn3 eutectic structure to combine with AZ31 base metal.

The Determination of the Orientation Relationship Between Primary and Eutectic Aluminum in A.Cast 319 Aluminum Alloy

2001 ◽  
Vol 7 (S2) ◽  
pp. 1250-1251
Author(s):  
W.T. Donlon ◽  
J.W. Zindel
Keyword(s):  
Orientation Relationship ◽  
Detailed Examination ◽  
Eutectic Structure ◽  
Similar Data ◽  
Solidification Behavior ◽  
Electron Backscattered Diffraction ◽  
Eutectic Region ◽  
Optical Micrograph ◽  
Transmission Electron ◽  
Engine Blocks

Cast 319 aluminum is an important automotive alloy used for engine blocks and cylinder heads. in order to “optimize” the as-cast microstructure and physical properties, a detailed understanding of its solidification behavior is required. One aspect of the solidification behavior which is not well understood is the mechanism by which aluminum and silicon in the eutectic regions nucleate. Figure 1 is an optical micrograph which identifies the aluminum dendrites, the Al-Si eutectic region, iron intermetallics, and Al2Cu particles. Dahle, Hjelen & Arnberg have utilized electron backscattered diffraction (EBSD) patterns, obtained with an SEM, on several Al-Si alloys to examine the orientation relationship between the aluminum in the eutectic to that of the surrounding aluminum dendrites. in this investigation transmission electron microscopy (TEM) is used to provide a more detailed examination of this eutectic structure while selected area diffraction (SAD) provide similar data to EBSD on the orientation relation between regions of primary and eutectic aluminum.

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