AlSi10Mg Alloy Research Articles

Engineering an ultra-fine grained microstructure, twins and stacking faults in PBF-LB/M Al-Si alloy via KoBo extrusion method

In this study, the microstructural and mechanical properties of an PBF-LB/M AlSi10Mg alloy extruded by the KoBo process are investigated. Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses revealed an ultrafine-grained face-centred cubic (f.c.c.) matrix with a high density of stacking faults (SFs) and Σ-CSL twin boundaries (TBs). The KoBo processed sample exhibited an attractive combination of mechanical properties - moderate tensile strength of 324 MPa and excellent ductility - elongation at break of ∼10%. The unique alloy microstructure obtained has the potential to exhibit superior properties such as improved radiation resistance, high temperature stability, resistance to intergranular corrosion and cyclic deformation. Overall, the results of this study provide a simple way to tailor the strength and ductility of PBF-LB/M-Al-Si alloys through grain boundary engineering and manipulation of TBs and SFs through interface engineering.

On the cyclic deformation behavior and correlated damage mechanism of selective laser melted AlSi10Mg alloy holding different initial microstructures

The present work deals with the cyclic deformation behavior of AlSi10Mg alloy fabricated through selective laser melting. Toward this end, the printed material was heat treated and was tested through strain-controlled push–pull fatigue under different strain amplitudes. The highest strengths were recorded for the direct aged, as-built and solutionized microstructures, respectively. The directly aged microstructure was characterized by the transformation of the columnar solidified structure into the equiaxed one and formation of the nano-Si precipitates. This was led to the best fatigue performance where an outstanding balance between the fatigue life and strength level was recorded. The low aspect ratio of the melt pools intensified the Marangoni effect, therefore, caused concentration of the material flow on the wetting side. This led to crack initiation and propagation at the end of the melt pools and formation of balling defects. Balling defect was characterized as the initiation site in the case of as-built and directly aged specimens, the cone-like geometry of which resulted in crack path deflection and a better fatigue performance. For solution treated microstructure, the melt pools were dissolved and the lack of fusion holding a critical size and located close to the surface, was characterized as the main crack initiation site.

Durable Polyacrylic/Siloxane-Silica Coating for the Protection of Cast AlSi7Mg0.3 Alloy against Corrosion in Chloride Solution.

This study presented a novel corrosion protective coating based on polyacrylic/siloxane-silica (PEHA-SS) deposited on lightweight cast aluminium alloy AlSi7Mg0.3. The synthesis of PEHA-SS comprises organic monomer 2-ethylhexyl acrylate and organically modified silane 3-(trimethoxysilyl)propyl methacrylate as well as an inorganic silane, tetraethyl orthosilicate. The steps during the synthesis process were monitored using real-time infrared spectroscopy. The coating deposited onto the AlSi7Mg0.3 surface was characterised using various techniques, including infrared spectroscopy, 3D contact profilometry, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The corrosion resistance of the coated alloy in sodium chloride solutions was evaluated using electrochemical impedance spectroscopy. The accelerated testing of the uncoated and coated sample was performed using the Machu test. This novel, nine micrometres thick PEHA-SS coating achieved durable corrosion (barrier) protection for the AlSi7Mg0.3 alloy in 0.1 M NaCl during the first four months of immersion or under accelerated corrosion conditions in a Machu chamber containing NaCl, acetic acid, and hydrogen peroxide at 37 °C.

Morphology of Al-2.5%Mg/xSiCp Composite developed by Stir Casting Process

. The research was conducted to enhance and solve the issues associated with low wettability and insufficient bonding between aluminum and silicon carbide that usually associated with stir casting process. The study used magnesium, heat treatment of SiCp and metallic (SiO2) coating on SiCp for improved Al-SiCp wettability in the manufacture of composite. The wt.% of SiCp was varied from 5 wt.% to 20 wt.% (uncoated and coated) at 5 wt.% intervals. The characterization conducted are XRD, XRF and SEM on the samples developed. XRD plots confirmed existence of Al with major peaks at 38.5, 45.11, 65.35, and 78.31; while Mg and SiCp were seen at 34.82 and 60.78 respectively. The XRF analysis revealed that major elements are within the range proposed for research with Alumina contains the highest amount of 70.05 – 86.69 wt.%, followed by Magnesium with 2.46 - 2.57 wt.%, and silicon having varying values of 0.91 wt.% for Sample A, 5.91 – 21.01 wt.% for uncoated samples B – E, and higher values of 8.43 – 24.43 wt.% for Samples F – I compared to the control sample, while all other minerals present are in such negligible proportion. The SEM/EDS results showed a fair dispersion of the SiCp particles in the samples with weight percentages of Al between 54.3 – 72.7 wt.%, Mg with 2.33 wt.% for control sample and a higher of values of 3.90 – 8.22 wt.% for composite samples, and Si with 0.10 – 1.32wt.%. Owning to this best performance test results, the coated Al-2.5%Mg/10wt%SiCp (Sample G) may be adopted as an alternate monolithic alloy to the existing AlMn, AlMg and AlMgSi alloys for structural, heavy machineries and marine applications where light weight is required.

Effects of processing parameters on pore defects in blue laser directed energy deposition of aluminum by in and ex situ observation

A single track, as the basic unit of laser directed energy deposition (L-DED) process, plays a significant role in the dimensional accuracy and mechanical performances of the ultimate products. However, there is almost no systematic investigation on the formation process and three-dimensional characteristics of the internal pore defects. Here, we used a high-speed camera, laser scanning confocal microscope (LSCM), and synchrotron radiation X-ray computed tomography (SR-CT) to study single tracks of AlSi10Mg alloy fabricated by blue laser directed energy deposition (BL-DED). A comprehensive investigation is conducted on the impact of processing parameters on the sizes, shapes, and formation mechanism of pore defects. Three types of pore defects are examined in single tracks: Type I lack of fusion, Type II spherical gas pores and Type III large irregular pores. Besides, large irregular pores are the transition between other two types. In particular, the results of SR-CT show that porosity decreases gradually with the increment of laser power and scanning speed. Therefore, high laser power accompanying with fast scanning speed will reduce the porosity. The lowest porosity of 0.074% is achieved under the power at 1600 W with scanning speed at 1080 mm/min, which has an obvious improvement over the current infrared L-DED. In addition, the mapping relationship among laser power, scanning speed and pore defects is established, which will provide a fundamental understanding of the origin of the defect and strategies for controlling the defect in L-DED towards high-quality printing.

Effect of a Pulsed Magnetic Field on the Structure and Properties of AlSi10Mg Alloy Plates Produced by Selective Laser Melting

Effect of a Pulsed Magnetic Field on the Structure and Properties of AlSi10Mg Alloy Plates Produced by Selective Laser Melting

The competing role of defects and surface roughness on the fatigue behavior of additively manufactured AlSi10Mg alloy

The fatigue behavior of AlSi10Mg alloy processed by laser-based powder bed fusion of metals (PBF-LB/M) in as-built (AB) and surface treated conditions, is assessed. A new chemo-mechanical polishing (CMP) surface treatment is applied to AB specimens to achieve an average surface roughness of Sa≈ 0.3 μm which is more than two orders of magnitude lower than that of AB specimens (Sa≈ 48.6 μm). The CMP surface treatment led to a significant improvement in fatigue strength of the alloy as compared to the AB material. The fatigue life of AB + CMP specimens is discovered to be governed by surface or near surface defects, whereas the deepest surface roughness valleys play a dominant role in controlling the fatigue behavior of the AB material. A simplified fracture mechanics-based fatigue life modeling approach was developed by combining real-time defects distribution data from 3D computed tomography (CT) and surface profilometry measurements. The model provided a quick and effective medium for obtaining reasonable first-order fatigue life approximations for AlSi10Mg alloy fabricated using PBF-LB/M.

Revealing the strengthening contribution of stacking faults, dislocations and grain boundaries in severely deformed LPBF AlSi10Mg alloy

In this study, microstructural features direct metal laser melted (DMLM) aluminium–silicon-magnesium (AlSi10Mg) are investigated using advanced transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The focus is on post-processing by ECAP (Equal Channel Angular Pressing) and its effects on grain refinement, stacking fault formation and dislocation accumulation. In addition, the strength enhancing role of stacking faults is for the first time quantified. The results show that ECAP can increase the yield strength from 294 to 396 MPa, while the elongation increases from 2.4% to 6%. These results show that ECAP processing offers a new approach for producing AlSi10Mg products with improved strength and ductility.

Predictive modeling of porosity in AlSi10Mg alloy fabricated by laser powder bed fusion: A comparative study with RSM, ANN, FL, and ANFIS

Predictive modeling of porosity in AlSi10Mg alloy fabricated by laser powder bed fusion: A comparative study with RSM, ANN, FL, and ANFIS

Influence of eutectic-Si in as-cast and fibrous-eutectic-Si in LPBF-processed AlSi10Mg alloys on wear and corrosion behaviors treated with direct aging route

Influence of eutectic-Si in as-cast and fibrous-eutectic-Si in LPBF-processed AlSi10Mg alloys on wear and corrosion behaviors treated with direct aging route

Influence of Laser Power on Microstructure and Wear Behavior of Additively Manufactured AlSi10Mg Alloy

Influence of Laser Power on Microstructure and Wear Behavior of Additively Manufactured AlSi10Mg Alloy

Influence of erbium addition on microstructure and performances of AlSi10Mg alloy prepared by selective laser melting

The effect of rare earth addition on the microstructure and mechanical performances of as-cast and wrought Al alloys has been attracting increasing attention recently. Rare earth addition has great potential in modifying the structure and improving the properties of materials. However, there are currently few reports about the effect of rare earth addition on the microstructure and performances of Al alloys prepared via selective laser melting. Here, AlSi10Mg alloys were manufactured using selective laser melting, and the effect of Er addition was investigated. The results indicate that Er addition leads to α-Al refinement and modifies the minority Si phase. The formation of the Al3Er phase induced by Er addition enhances the strength of the material. Modification of the Si phase also increases ductility. This strategy can help improve the mechanical performance of aluminum alloys prepared via selective laser melting.

In situ synchrotron x-ray imaging and diffraction study of additively manufactured AlSi10Mg alloy under uniaxial tension

In situ synchrotron x-ray imaging and diffraction are used to investigate deformation dynamics in two kinds of additively manufactured AlSi10Mg with different pore configurations. The pre-existing pore configurations are characterized with synchrotron x-ray computed tomography. The specimens are subjected to tensile loading along the build direction and the longitudinal direction. Bulk stress–strain curves (macroscale), strain fields (mesoscale) and x-ray diffraction patterns (microscale) are obtained simultaneously. Scanning electron microscopy characterization is performed as a complement. For the small-pored AlSi10Mg, preferred orientations of pores lead to anisotropic ductility, and only ductile dimples are observed. For the large-pored AlSi10Mg, ductility loss is significant due to its higher porosity, and no remarkable anisotropy is found; both ductile and brittle fracture features are identified. For both types of AlSi10Mg, strain localization occurs around the pores. At the lattice scale, the Al matrix deforms plastically but the Si phase is still strained elastically, and thus, significant stress concentration occurs in the Si phase for the small-pored AlSi10Mg, while stress is more evenly partitioned between the Al matrix and the Si phase for the large-pored AlSi10Mg.

Alternations of hardness and tensile properties of the ultrasound-assisted aging treatments on the Al-Mg-Si alloy

Lightweight metals with appropriate strength are crucial materials among the critical future technologies and sustainable issues. The Al-Mg-Si alloys, which are processed by aging treatments, are considered promising candidates. Hence, the pseudo-binary Al-Mg2Si alloy with an excess Si addition was chosen in this study. In addition, to further manipulate the alloys, besides to the often-controlled two factors of aging temperature and aging time, ultrasound was introduced into the aging system as an additional third factor to further control the aging behaviors. One-step and two-step aging treatments were both conducted to verify the effect of the introduction of ultrasound. It was found that certain alternations of mechanical properties, such as micro Vickers hardness, which is a surface property, were obviously imposed. On the other hand, the tensile strength and fracture strain, which are bulk mechanical properties, showed limited changes between the ultrasound-applied and ultrasound-free specimens. Many possibilities have been proposed and discussed for the observed phenomenon. The cavitation would be the greatest factor in the alternation of the micro Vickers hardness. Microstructures observed by bright-field images were in good accordance with that of the observed mechanical properties.

Very High Cycle Fatigue Properties and Damage Evolution in Al-Si Cast Alloys

Abstract The steady progress in electro mobility increases the demand for lightweight space frame and engine solutions. Advanced aluminum-silicon cast alloys with additions of magnesium, copper, or both for precipitation hardening are promising candidates for lightweight structures because of their high strength-to-weight ratio. For a reliable design, the fatigue performance in the very high cycle fatigue (VHCF) regime must be understood. Therefore, this study deals with the influence of frequency on VHCF properties as well as fatigue damage evolution in AlSi7Mg and AlSi10Mg sand-cast alloys. The VHCF tests were performed using a resonant (70 Hz), a high-frequency resonant (1 kHz), and an ultrasonic (20 kHz) fatigue testing system. Thereby, a significant frequency effect could be determined that resulted in an increased fatigue lifetime by 1 decade at 1 kHz and by 2 decades at 20 kHz, whereas no significant change in fatigue limit could be determined. Moreover, the fatigue crack initiation mechanisms change from surface crack initiation at 70 Hz and 1 kHz to volume crack initiation at 20 kHz. Using the defect-based Murakami approach, including a lightweight extension of Noguchi, a defect-induced (size, location) frequency effect could be excluded. Based on damage monitoring, the effect could be related to the crack propagation phase, which is accelerated at low frequencies (<100 Hz) because of a humidity reaction with the fatigue crack surface and the formation of atomic hydrogen resulting in a saturated hydrogen embrittlement per cycle. At high frequencies of 1 kHz and 20 kHz, no saturated hydrogen embrittlement per cycle can be reached.

Studies on mechanical and corrosion behaviour of heat-treated AlSi10Mg alloy fabricated by PBF-LM

Studies on mechanical and corrosion behaviour of heat-treated AlSi10Mg alloy fabricated by PBF-LM

Experimental and statistical investigation of mechanical properties and surface roughness in additive manufacturing with selective laser melting of AlSi10Mg alloy

Experimental and statistical investigation of mechanical properties and surface roughness in additive manufacturing with selective laser melting of AlSi10Mg alloy

Flame-sprayed MgAl2O4- and calcium aluminate-based coatings for application in the aluminium industry

The aluminium industry is a major consumer of refractories with increasing wear by fluxes, the use of oxy-fuel burners, higher furnace temperatures, higher amounts of alloying Mg and recycled Al metal as well as a requirement for higher efficiencies. Today, most furnaces are lined with aluminosilicate-based materials. The reactions between the aluminosilicate and the metal lead to the formation of a mixture of Si, Al, and Al2O3 with unreacted refractory material, which has to be removed as they negatively affect the thermal properties of the refractories and the efficiency of the furnace. To reduce the penetration of Al into the refractory material, non-wetting additives such as barium sulphate, different types of fluorides, and CaO were used. The aim of this study was the investigation of different calcium aluminate-based coatings to reduce the wettability of a metallic substrate by molten aluminium. Feedstock composed of calcium magnesium aluminate CMA, calcium di-aluminate CA2, and CA/CA2 with and without TiO2 were characterised and processed via powder and flame spraying to thin coatings on metal substrates. The spraying parameters have been optimized and the phase composition, roughness, macro- and microstructure, porosity, and bending strength of the coatings have been analysed. Additionally, a finger test, as well as a casting test, have been performed by pouring 1.5 kg AlSi7Mg alloy at 800 °C over coated half-pipes using pure alumina as reference coating. The amount of residual Al sticking on the substrates after the casting test indicates the degree of wetting of the coatings. The thermally sprayed CMA and CA2 powder feedstock showed the lowest degree of interaction with the aluminium melt.

The role of internal defects on anisotropic tensile failure of L-PBF AlSi10Mg alloys

This paper investigates the effects of defects on tensile failure of additive manufactured AlSi10Mg alloy focusing particularly on the role of large pancake shaped loss of fusion (LOF) defects lying perpendicular to the build direction (BD). Time-lapse in situ synchrotron radiation X-ray micro-computed tomography during straining reveals how, when tested parallel to the BD, the LOF defects extend laterally with straining connecting to other defects and giving rise to low plasticity and an essentially brittle failure mode. When they are aligned edge-on to the straining direction, failure is characterised by a ductile cup-cone failure with significant elongation of the defects axially and extensive necking prior to failure. The soft fish-scale melt pool boundaries were also found to affect the fracture path. These results highlight the anisotropic effect of loss of fusion defects in controlling tensile ductility and the need to minimize their size and aspect ratio. In cases where these cannot be fully eliminated the component should be fabricated such that the BD is not aligned with the dominant in-service loading direction.

Laser ultrasonic detection of submillimeter artificial holes in laser powder bed fusion manufactured alloys

In the development of additive manufacturing (AM) technology, laser powder bed fusion (LPBF) is one of the important processing methods. However, the hole defects in the fabricated samples limit the development. Laser ultrasonic (LU) technology plays a major role in the detection of LPBF parts with tiny defects, which has the advantages of non-contact and non-destructive. In this work, the detection of submillimeter internal defects in four typical LPBF alloys by LU technology is studied numerically and experimentally. A multiphysics simulation model of LU detection is established to investigate the propagation characteristics of excited ultrasonic waves in different LPBF alloys and their interaction with submillimeter artificial defects. Simulation results show that the amplitude of longitudinal (L) wave at the defect is the largest in AlSi10Mg alloy, and the amplitude of L wave in the 316L alloy, Ti6Al4V alloy and In718 alloy are very close, but their phases are slightly different. The amplitude of L wave tends to decrease nearly linearly with the increase in defect diameter. Then, four typical LPBF alloys are fabricated and measured by the LU through-transmission detection. The geometric information of artificial holes with a diameter larger than 0.2 mm are clearly characterized by the LU C-scan results, indicating the prominent applicability and feasibility of LU detection on different materials fabricated by LPBF.