Manufactured AlSi10Mg Alloy Research Articles

Predicting the fatigue life of additively manufactured AlSi10Mg alloy using a physics-informed neural network incorporating continuous damage mechanics

The material characteristics of additively manufactured AlSi10Mg alloy, including the random distribution of process-induced micro defects, microstructual anisotropy, and grain morphologies with complex diversity, poses a significant challenge in accurately predicting its fatigue life, limiting its application in the aircraft field. This work herein introduces a novel approach incorporating a physics-informed neural network (PINN), in which an artificial neural network (ANN) is embedded with a damage mechanics model (CDM) and the critical process parameters of laser powder bed fusion (L-PBF) additive manufacturing. The partial differential equations of the updated CDM model are introduced into the training procedures of the PINN to building a loss function, effectively “teaching” the PINN to learn the physical knowledge. A comparison of the fatigue life prediction results of ANN and the proposed PINN models shows that the PINN model outperforms its counterparts with a 38.71% higher prediction accuracy. The effects of L-PBF process parameters on the fatigue life of as-built AlSi10Mg is examined using both ANN and PINN, proving the better predictive performance and data-physics consistency of the PINN model. The scheme of this work can inform the efficient prediction of fatigue life of additively manufactured alloys and also reverse prediction or fast finding of optimized process parameters for additive manufacturing.

Influence of heat treatment and anodizing on the corrosion behaviour of additive manufactured AlSi10Mg alloy

Influence of heat treatment and anodizing on the corrosion behaviour of additive manufactured AlSi10Mg alloy

A generalized machine learning framework to estimate fatigue life across materials with minimal data

In this research, a generalized machine learning (ML) framework is proposed to estimate the fatigue life of epoxy polymers and additively manufactured AlSi10Mg alloy materials, leveraging their failure surface void characteristics. An extreme gradient boosting algorithm-based ML framework encompassing Synthetic Minority Over-sampling TEchnique (SMOTE), categorical data encoding, and external loop cross-validation is developed to evaluate the fatigue life across materials. The influence of different training strategies based on materials, input features, encoding method, and data standardization on the model performance is explored. Additionally, the importance of anti-data-leakage and anti-overfitting measures over the ML model performance is addressed. The result shows that the data-leakage-free, external loop cross-validated model can estimate the fatigue life of selective epoxy polymers and metal alloys with an average R2 of 0.71 ± 0.06 using a mere 12 to 27 experimental data points per material category. Whereas the model trained with data-leakage and overfitting results in high R2 of 0.9.

Sustaining Cellular Structures in Additively Manufactured AlSi10Mg Alloy via Heat Treatments

Sustaining Cellular Structures in Additively Manufactured AlSi10Mg Alloy via Heat Treatments

Multimodal and Correlated STEM Analysis to Generate Stress Maps of Additive Manufactured AlSi10Mg Alloy

Multimodal and Correlated STEM Analysis to Generate Stress Maps of Additive Manufactured AlSi10Mg Alloy

Ultimate Tensile Strengths and Elastic Moduli at 20 K of Additively Manufactured PA840-GSL, A6061-RAM2, and AlSi10Mg

The additive manufacturing (AM) of polymer matrix composites (PMCs) and metal matrix composites (MMC) systems presents novel opportunities for reducing the mass of aerospace vehicles. These solutions also have the potential to reduce the cost of terrestrial applications where cryogenic temperatures are present. To address this need, this paper explores the mechanical characterization of three AM materials at 20 K: a nylon-based PMC PA840-GSL, and two aluminum-based MMCs A6061-RAM2 and AlSi10Mg. A Cryogenic Accelerated Fatigue Tester (CRAFT) used for the mechanical testing is first detailed. Next, ultimate tensile strengths and elastic moduli of the additively manufactured AlSi10Mg alloy and A6061-RAM2 are obtained. Third, the mechanical performance of an additively manufactured PMC liquid hydrogen tank constituent is collected in addition to an analysis on the effect the processing parameters, such as scan spacing, have on the mechanical behavior. A6061-RAM2 exhibited superior mechanical performance and is recommended for structural applications. Variation of PA840-GSL scan spacing resulted in decreased mechanical performance.

Numerical investigation on effect of different projectile nose shapes on ballistic impact of additively manufactured AlSi10Mg alloy

In the last few years, due to the superior mechanical qualities of Additive Manufacturing (AM) AlSi10Mg alloy to those of traditional casting process AlSi10Mg alloys, the application of AM technology has significantly increased. The ballistic impact research has a wide range of uses, notably in the mining, construction, spacecraft and defence sectors. This work focuses on analyzing the behavior of different projectile nose shapes on the AlSi10Mg alloy fabricated by AM. There are several projectile nose forms to consider, including blunt, hemispherical, conical, and ogive shapes. The impact of various projectile shapes on the ballistic limit of the additively created AlSi10Mg alloy is carefully examined in this study. All numerical simulations were carried out using LS-DYNA software, and the Johnson-Cook material and damage model were considered to assess the ballistic resistance behavior. The ballistic limit for various projectile shapes is computed using the Jonas-Lambert model, which describes the connection between residual velocity and starting projectile velocity. The results showed that, the ogive-shaped Projectile offers the highest ballistic limit, and the blunt projectile shows the lowest ballistic limit for a 5 mm thin target plate. The ballistic impact phenomenon showed plugging failure for the blunt nose projectile, the formation of plug and small fragments were observed in the case of hemispherical nose projectile, fragmenting failure is observed with radial necking in the case of conical nose projectile and petals are formed at the impacted zone in ogive nose shape projectile. Moreover, the ballistic limit of AM AlSi10Mg alloy was slightly higher compared to the ballistic limit of the die-cast AlSi10Mg alloy for the 7.62 mm AP bullet (core). Therefore, AM AlSi10Mg alloy may have equal or good ballistic properties compared to die-cast AlSi10Mg alloy.

Micromechanical study of intragranular stress and strain partitioning in an additively manufactured AlSi10Mg alloy

This study addresses the effect of a cellular-dendritic microstructure on the intragranular deformation behavior of an additively manufactured AlSi10Mg alloy. Experimental investigations have revealed the Al dendritic cells with a characteristic size of several hundred nanometers. The cells are decorated by a thin eutectic layer which consists of an aluminum matrix reinforced by silicon nanoparticles. Based on the experimental data, a set of micromechanical models are constructed and implemented in finite-element calculations. The constitutive behavior of an aluminum phase is described in terms of anisotropic elasticity to take into account the crystal lattice effects. Calculation results are analyzed and discussed with the main focus being placed on the effect of microstructure-resolved stress and strain partitioning between Al and Si phases. The silicon content is shown to impact the range of stress variation at the intragranular scale and the places of stress concentration in the Al phase. The eutectic layer behaves as a metal matrix composite where reinforcing silicon particles restrict deformation of the aluminum matrix.

ANALYSIS OF ADDITIVELY MANUFACTURED AlSi10Mg ALLOY USING X-RAY DIFFRACTION

This research deals with the study of additively manufactured AlSi10Mg alloy samples by X-ray diffraction. The effect of sample orientation during 3D printing by Selective Laser Melting on the values of macroscopic residual stresses and microstructural parameters and their possible inhomogeneities of the cylindrical sample was investigated. Phase analysis identified the intermetallic phase Mg2Si in addition to the major phases (solid solutions of Al and Si). Tensile residual stresses weredetected in the surface layer for all samples. Inhomogeneities of the investigated parameters of all samples were observed along the circumference of the shank. These effects may be related to the direction of the layers relative to the axis of the sample. These inhomogeneities form so-called microstructural notches or weak spots that are prone to the formation of fatigue cracks, which have a major influence on the fatigue life.

Effect of placement configuration on the microstructure, porosity and mechanical performance of dissimilar remote laser welding of additive manufactured AlSi10Mg alloy and conventionally manufactured 1050 aluminium sheet

Additive manufacturing (AM) has gained significant attention in automotive applications, while the low weldability of AM material poses challenges when assembling AM materials with conventionally manufactured materials. This study investigated the laser welding of AM AlSi10Mg and AA1050 sheet metal in an overlap configuration, specifically focusing on the impact of placement configuration of two materials on weld properties. This aims to provide valuable insights for optimizing the localized geometry of AM components to enhance the joint performance. Results showed that positioning AM AlSi10Mg on top leads to a higher weld penetration and higher Si content within the molten pool, especially in the upper sheet. Additionally, weld zone grain structure was greatly influenced by alternating the placement configuration, where welds with AM AlSi10Mg on top exhibiting more equiaxed grains in the weld centre and refined columnar grains near the fusion boundary of upper sheet. Furthermore, significantly reduced weld porosity was determined by positioning AM AlSi10Mg at the bottom (3.2 ± 0.4 %∼7.1 ± 0.9 %) compared to placing it on top (16.9 ± 0.9 %∼20.1 ± 0.9 %) in all scenarios ranging from full penetration to partial penetration. This can be related to the fact that the hydrogen bubbles originating from AM AlSi10Mg experienced a shorter exposure in the molten pool, limiting the merging and growth of small bubbles. However, a slightly lower joint strength was determined in welds with AM AlSi10Mg at the bottom which may be due to the plastic deformation incompatibility between large columnar grains in the fusion zone and the fine grains in the as-printed material.

Study of the effect of functionalization with inhibitors on the corrosion properties of PEO-coated additive manufactured AlSi10Mg alloy

Plasma electrolytic oxidation (PEO) was carried out on SLM-produced AlSi10Mg alloy using various corrosion inhibitor additives. The study investigated the effects of these additives on microstructural evolution, phase composition, and corrosion behavior by comparing the functionalized coating to a standard base silicate PEO one. The results revealed that, in most cases, the additives significantly altered the coatings' thickness, density, and adherence, leading to improved corrosion resistance due to an enhanced barrier effect over electrolyte penetration. Long-term immersion electrochemical impedance spectroscopy (EIS) tests proved the additives’ corrosion inhibitor capability, as they all were able to enhance coating stability.

The effect of thermal history on the additively manufactured AlSi10Mg alloy response to ion irradiation

Aluminum alloys, mainly from the 5xxx and 6xxx families, are used extensively in research reactors due to their suitable properties. However, alloys common in nuclear applications are not yet suitable for Additive Manufacturing (AM). The alloy AlSi10Mg has good engineering properties and is the most used and investigated AM Al-alloy. In this work, stress relieved (SR) samples of AM AlSi10Mg have been compared to samples that underwent a subsequent heat treatment at 500°C (SHT), producing two distinctly different microstructures. The SHT samples contain larger grains with a cleaner matrix and coarser silicon particles compared to the SR samples. Samples with the two microstructures were irradiated using silicon ions up to damage of ∼20 dpa at a depth of about 1 µm. To compare the response of both conditions to irradiation, properties were measured using nano-indentation and transient grating spectroscopy (TGS). Microstructure was characterized using TEM. Results show that the SHT condition is much more sensitive to irradiation, compared to SR. Irradiation caused thermal diffusivity to decrease by ∼5% in the SR condition and by more than 50% in the SHT condition. Hardness increased by 12 and 24% in the SR and SHT conditions, respectively. Also, the void number density was significantly larger in the SHT condition. No change was observed in young's modulus. The lower sensitivity of the SR condition is attributed to a higher sink density present in the initial microstructure, resulting in overall less irradiation damage retained in the material after irradiation. The explanation offered for the major drop in thermal diffusivity observed only in the SHT condition is the large size of the silicon particles, which increases their instability during irradiation, causing them to partly dissolve and release atomic silicon into the matrix around them. These silicon atoms are effective electron and phonon scatter centers. The findings of this work show that the pre-irradiated microstructure of AM AlSi10Mg has a crucial role in the material's performance in nuclear reactor core conditions. Careful thought and care need to be implemented to the heat treatment applied to an as-built part.

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.

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

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.

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.

In situ X-ray imaging of electrochemical dissolution behavior at low current density of as-built additively manufactured AlSi10Mg alloy

Despite extensive research on electrochemical machining (ECM) for improving the surface quality of additively manufactured (AMed) metals, common problems of stray corrosion and uneven dissolution remain. Here, in-situ synchrotron X-ray imaging was firstly used for observing the dissolution behavior of as-built AlSi10Mg alloy at low current density. The bubble evolution, surface roughness and dissolved depth was investigated. The results demonstrated that surfaces with higher roughness exhibited a greater dissolution rate and consumed a larger proportion of electrons compared to smooth surfaces. The study also identified three distinct stages of surface roughness change at low current density, providing valuable insights for the development of ECM techniques for AMed parts.

Characterisation of Microstructure and Special Grain Boundaries in LPBF AlSi10Mg Alloy Subjected to the KoBo Extrusion Process

Grain boundary engineering (GBE) enhances the properties of metals by incorporating specific grain boundaries, such as twin boundaries (TB). However, applying conventional GBE to parts produced through additive manufacturing (AM) poses challenges, since it necessitates thermomechanical processing, which is not desirable for near-net-shape parts. This study explores an alternative GBE approach for post-processing bulk additively manufactured aluminium samples (KoBo extrusion), which allows thermo-mechanical treatment in a single operation. The present work was conducted to examine the microstructure evolution and grain boundary character in an additively manufactured AlSi10Mg alloy. Microstructural evolution and grain boundary character were investigated using Electron Back Scattered Diffraction (EBSD) and Transmission Electron Microscopy (TEM). The results show that along with grain refinement, the fraction of Coincidence Site Lattice boundaries was also increased in KoBo post-processed samples. The low-Σ twin boundaries were found to be the most common Coincidence Site Lattice boundaries. On the basis of EBSD analysis, it has been proven that the formation of CSL boundaries is directly related to a dynamic recrystallisation process. The findings show prospects for the possibility of engineering the special grain boundary networks in AM Al–Si alloys, via the KoBo extrusion method. Our results provide the groundwork for devising GBE strategies to produce novel high-performance aluminium alloys.

Microstructural analysis of the influences of platform preheating and post-build heat treatment on mechanical properties of laser powder bed fusion manufactured AlSi10Mg alloy

Platform preheating is a common strategy towards reducing residual stress and distortion of additively manufactured metal components by powder bed fusion – laser beam (PBF-LB) due to the lowered thermal gradient. However, platform preheating can lead to in-situ ageing for aluminium alloy components in the building process, which will affect the mechanical properties. In this work, the microstructures of PBF-LB AlSi10Mg built on preheated (150 °C) and un-preheated (ambient) platforms have been characterized in detail by various electron microscopy techniques in order to better understand the influence of platform preheating on mechanical properties. Furthermore, the influences of T5 ageing and solution treatment plus ageing (T6) on microstructure and mechanical properties have also been examined. Platform preheating to 150 °C improves strength, which is associated with the in-situ precipitation of granular or rod-shaped Si phase and needle-like β'' phase. To the best of our knowledge, this is the first report on the observation of β'' precipitates in PBF-LB Al–Si–Mg alloys in the as-built state. Upon T5 treatment, the ambient platform material exhibits significant age hardening while only marginal age hardening is observed for the 150 °C platform material. Consequently, the materials built at different platform temperatures show similar mechanical properties after T5 treatment. The age hardening response is more pronounced when a rapid solution treatment (RST, 520 °C for 10 min) is adopted instead of the conventional solution treatment (CST, 520 °C for 2 h) owing to the precipitation of a higher number density of needle-like β'' phase during ageing. The T5 treatment improves both yield strength and tensile strength, but the improvements in strength are accompanied by a reduction in ductility. On the other hand, the RST-T6 treatment substantially improves ductility and reduces the tensile strength while maintaining the yield strength for the 150 °C platform material. Based on the microstructural analysis, the influences of platform preheating and post-build heat treatment on mechanical properties of PBF-LB AlSi10Mg are discussed.

Insights into the microstructure evolution and mechanical behavior of dissimilar friction stir welded joints of additively manufactured AlSi10Mg and conventional 7075-T651 aluminum alloys

Metal 3D printing through laser powder bed fusion (L-PBF) has revolutionised the manufacturing industry. However, size limitations and production costs persist as challenges for the 3D printing of metallic alloys. Thus, joining L-PBF components to other parts becomes a vital aspect to produce composite structures for engineering applications. Among the dissimilar joining of various non-ferrous alloys, the integration of L-PBF components with difficult-to-join materials, such as aerospace-grade AA-7XXX aluminum alloys, still remains an unaddressed industrial problem. To address this problem, the current study was carried out to investigate the feasibility of joining L-PBF manufactured AlSi10Mg alloy with a traditionally rolled AA7075-T651 alloy using friction stir welding process. In this study, the influence of the base material positioning and heat input on the mechanical and metallurgical characteristics of welded joints was examined, followed by their interrelationships for more efficient adoption of this technology. The results revealed that the base material placement significantly influenced the joint strength at low heat input but showed negligible impact at high heat input. The joints fabricated at high heat input exhibited higher hardness within the nugget zone owing to the higher concentration of MgZn2 and β-Mg2Si secondary-phase particles as compared to the joints fabricated at low heat input. Texture analysis of welds showed that the C {001} <110> shear component dominated the nugget zone when AA7075-T651 was placed on the retracting side. Whereas, the A1*/ A2* {111} <1‾12‾ >/{111} <112‾ > simple shear component was prominent when AA7075-T651 was placed on the advancing side of the joint. Finer grains and high dislocation density in the nugget zone at low heat input resulted in the maximum joint efficiency of 77% with respect to the AlSi10Mg alloy. In contrast, a coarse grain structure at high heat input reduced the joint efficiency to 74%. The findings from this research suggest friction sir welding to be an efficient method for dissimilar joining of additive components with conventionally manufactured parts.