Changes in the microstructure and mechanical properties of additively manufactured AlSi10Mg alloy after exposure to elevated temperatures

Fousová, Michaela; Dvorský, Drahomír; Michalcová, Alena; Vojtěch, Dalibor

doi:10.1016/j.matchar.2018.01.028

Cited by 197 publications

(92 citation statements)

References 29 publications

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“…29 Small kinks observed on the DSC curves near 480°C during DSC measurements in both as-built and reference samples may be an indication of the latter event. However, the low temperature event (i.e., GPZ formation) was absent in AM fabricated AlSi10Mg parts in our study 14 and other studies 13,18,22,32 Additionally, the nanoscale precipitates observed in the primary a aluminum are not intermetallic compounds but pure Si. 18,32 The disparity can be attributed to the differences in microstructure and chemical distribution during the quenching/ solidification process.…”

Section: Disscussioncontrasting

confidence: 52%

“…However, the low temperature event (i.e., GPZ formation) was absent in AM fabricated AlSi10Mg parts in our study 14 and other studies 13,18,22,32 Additionally, the nanoscale precipitates observed in the primary a aluminum are not intermetallic compounds but pure Si. 18,32 The disparity can be attributed to the differences in microstructure and chemical distribution during the quenching/ solidification process. In a conventional solution treated alloy, in addition to a dendritic solidification structure, the primary a aluminum forms a homogenous solid solution with maximum levels of Mg and Si as predicted by solubility and alloy composition limits 3 while the rapid solidified AM part develops a unique cellular microstructure with inhomogeneous compositions and different phases due to chemical partitioning or microsegregation.…”

Section: Disscussioncontrasting

confidence: 52%

“…Above the Debye temperature of Al (h D ; 150°C, Table I) where Si diffusion becomes active, Si exolution occurs and forms uniformly dispersed nanosized Si precipitates in the a aluminum as illustrated by Fig. 6(c) as well as supporting evidence from the change in thermal expansion, the exolution of Si with in situ X-ray structural refinement, 14 as well as the energy dispersive X-ray spectroscopy imaging 32 and the selective area diffraction pattern from transmission electron microscopy. 18 The precipitation of smaller Si atoms from the Al lattice releases the extra stored elastic strain energy in the lattice and constitutes the first exothermic event peaked at 250°C.…”

Section: Disscussionmentioning

confidence: 55%

“…33 In the AM fabricated part, the primary a Al inside of the cellular structure is supersaturated with Si and most of the Mg and trace impurities are preferentially located in the cellular walls and triple junctions. 13,18,32 If the cellular structure remains intact at low temperatures, the deficiency of Mg in the primary a Al will prevent the formation of Mg and Si rich GPZs. Above the Debye temperature of Al (h D ; 150°C, Table I) where Si diffusion becomes active, Si exolution occurs and forms uniformly dispersed nanosized Si precipitates in the a aluminum as illustrated by Fig.…”

Section: Disscussionmentioning

confidence: 99%

“…This is evidenced by the monotonic yet moderate increase (first measurement, solid legends) in thermal diffusivity and the thermal conductivity between À50 and 150°C and the progressive increase in hardness with time by annealing at temperature below 150°C. 32 The increase in heat transfer with increasing temperature is uniquely related to the change in microstructure, as both thermal diffusivity and thermal conductivity are expected to decrease due to the increase of collisions between electrons and phonons as temperature increases in this temperature range. This is illustrated by the second measurement (hollow symbols) when some of these scattering centers are removed by thermal treatment at high temperatures.…”

Section: Disscussionmentioning

confidence: 99%

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Microstructure evolution and thermal properties of an additively manufactured, solution treatable AlSi10Mg part

et al. 2018

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Because of rapid solidification involved in the laser or e-beam based additive manufacturing (AM) process, solution treatable metallic parts made by these methods usually possess a unique nonequilibrium microstructure which changes significantly during subsequent thermal treatment. Such evolution alters the size, morphology, length scale, and distribution of microstructural features and has a substantial impact on thermal properties and possibly on electrical properties as well. This study focuses on effects of microstructural evolution on thermal properties of an additively manufactured AlSi10Mg part. The changes of thermal properties such as thermal expansion, heat capacity, thermal diffusivity, and thermal conductivity as a function of thermal treatment are reported. The results show that the formation of supersaturated primary a aluminum and unique cellular structure imparted by fast solidification in the AM process are the major cause for the low thermal diffusivity and low thermal conductivity observed in this solution treatable, as-built part. A correlation between microstructural evolution and changes in thermal properties is established. Advantages and tailoring of the thermal properties of additively built parts are discussed. Implications of these results are important for other additively manufactured components based on popular solution treatable alloys.

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Section: Disscussioncontrasting

confidence: 52%

Section: Disscussioncontrasting

confidence: 52%

Section: Disscussionmentioning

confidence: 55%

Section: Disscussionmentioning

confidence: 99%

Section: Disscussionmentioning

confidence: 99%

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Microstructure evolution and thermal properties of an additively manufactured, solution treatable AlSi10Mg part

et al. 2018

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High‐Temperature Behavior of the Heat‐Treated and Overaged AlSi10Mg Alloy Produced by Laser‐Based Powder Bed Fusion and Comparison with Conventional Al–Si–Mg‐Casting Alloys

et al. 2023

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The continuous research of new technologies and materials to reduce the CO 2 footprint has led to a significant interest in additive manufacturing (AM). In particular, the laser-based powder bed fusion (L-PBF) process represents one of the most attractive technologies currently available for producing complex-shaped components characterized by light structures and high mechanical performance. [1,2] Transportation and energy are probably the main industrial sectors that can significantly benefit from reducing the mass and size of mechanical parts manufactured by the L-PBF process to reduce their environmental impact. [3,4] Fuel injectors, heat sinks, mixing and swirling burner tips, pistons, gas turbines, and aerodynamic parts are, in fact, a few examples of possible L-PBF-produced components. [5][6][7] However, thin-walled and lattice design solutions require the continuous development of new thermally stable materials capable of withstanding the thermomechanical stresses caused by the severe operating conditions (high temperatures and long service times) occurring in automotive, aeronautical, aerospace, and energy applications. [8][9][10] Among the metals used in the L-PBF process, the Al-Si-Mg alloys represent an up-and-coming solution for producing structural components. [11] They meet both mechanical (high strength-to-weight ratio) and production requirements (good fluidity and weldability) compared to other Al-casting alloys, such as the heat-resistant Al-Cu and Al-Zn alloys. [12][13][14][15] The Si content close to the eutectic point reduces the solidification range and increases the powder bed's laser absorption, thus improving the melt pool (MP) fluidity and simplifying the printing process. [16] In addition, the high Mg content enables precipitation of the Mg 2 Si precursor phases during the printing process, further strengthening the Al matrix. [17,18] The AlSi10Mg alloy is currently the most common Al-Si-Mg alloy used in the L-PBF process. The cellular structure of the as-built (AB) L-PBF AlSi10Mg alloy consists of sub-micrometric cells of supersatured α-Al phase surrounded by a eutectic-Si network, which gives high hardness and tensile strength values at the expense of ductility. [19][20][21] However, as widely described by the authors in previous work, [22] the thermally activated diffusion processes alter the metastable microstructure of the AB alloy, acting on the size and morphology of the dispersed (nano-sized Si precipitates and precursors of the Mg 2 Si equilibrium phase) and aggregated (eutectic-Si network) strengthening phases. Consequently, given the complexity of the topic, the literature in recent years has mainly focused on the effects of process parameters and heat treatments on the microstructure and the mechanical properties at room temperature (RT) of the L-PBF

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Improving the Defect Tolerance and Fatigue Strength of AM AlSi10Mg

2023

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Additively manufactured structures reveal a poor surface quality and a high number of process‐induced defects in the surface‐near area, leading to a significant reduction of the fatigue strength. As laser‐based powder bed fusion (PBF‐LB) processes are used to produce topologically optimized lightweight structures with complex geometries, which cannot be fully machined, the influence of the process‐induced surface on the fatigue behavior needs to be analyzed. For this, also the interrelation of the surface‐induced notch effects with the surrounding material volume must be considered. As thermal treatments can also be applied to filigree components with complex geometries, in the presented work the influence of different heat treatments, i.e., stress relief annealing (SR) and artificial aging (T6), on the material properties, especially the defect tolerance, of AlSi10Mg manufactured via PBF‐LB is analyzed. Both heat treatments lead to a dissolution of the cellular Si‐rich network, resulting in decreased hardness and tensile strength, but higher fatigue strength. The increased fatigue strength results from a reduction of the process‐induced residual stresses, but mainly a strongly improved defect tolerance. Consequently, to evaluate the fatigue strength of additively manufactured materials, besides the materials strength and the process‐induced defects, also the defect tolerance must be considered.

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Changes in the microstructure and mechanical properties of additively manufactured AlSi10Mg alloy after exposure to elevated temperatures

Cited by 197 publications

References 29 publications

Microstructure evolution and thermal properties of an additively manufactured, solution treatable AlSi10Mg part

Microstructure evolution and thermal properties of an additively manufactured, solution treatable AlSi10Mg part

High‐Temperature Behavior of the Heat‐Treated and Overaged AlSi10Mg Alloy Produced by Laser‐Based Powder Bed Fusion and Comparison with Conventional Al–Si–Mg‐Casting Alloys

Improving the Defect Tolerance and Fatigue Strength of AM AlSi10Mg

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