Equiaxed grain formation by intrinsic heterogeneous nucleation via rapid heating and cooling in additive manufacturing of aluminum-silicon hypoeutectic alloy

Okugawa, Masayuki; Ohigashi, Yuta; Furishiro, Yuya; Nakano, Takayoshi

doi:10.1016/j.jallcom.2022.165812

Cited by 28 publications

(13 citation statements)

References 27 publications

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“…Columnar crystals grew epitaxially from the unmelted crystal placed outside. Furthermore, a previous study demonstrated the formation of equiaxed crystalline grains near the melt-pool boundary in Al-Si hypoeutectic alloy using Si crystalline particles as heterogeneous nucleation sites [ 30 ]. Under condition ②, Si crystalline particles did not remain after the remelting process, and therefore, equiaxed crystalline grains were absent from the resolidification microstructure.…”

Section: Resultsmentioning

confidence: 99%

“…The elucidation of the mechanism that underlies this phenomenon is a crucial challenge that would allow for the fabrication of metals with improved material properties through better control over the microstructures in AM. Through multiphase-field (MPF) simulations, we have demonstrated that the Si particles in eutectic regions near the melt-pool boundary of a solidified Al-Si alloy remain, even after the remelting process, because of the rapid heating rate of PBF-type AM; furthermore, such remaining crystalline Si particles act as heterogeneous nucleation sites for α-Al equiaxed crystalline grains [ 30 ]. This process has been proposed as the grain refinement and formation mechanism near the melt-pool boundaries.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Rapid Heating and Cooling Conditions on Microstructure Formation in Powder Bed Fusion of Al-Si Hypoeutectic Alloy: A Phase-Field Study

2022

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Al alloy parts fabricated by powder bed fusion (PBF) have attracted much attention because of the degrees of freedom in both shapes and mechanical properties. We previously reported that the Si regions in Al-Si alloy that remain after the rapid remelting process in PBF act as intrinsic heterogeneous nucleation sites during the subsequent resolidification. This suggests that the Si particles are crucial for a novel grain refinement strategy. To provide guidelines for grain refinement, the effects of solidification, remelting, and resolidification conditions on microstructures were investigated by multiphase-field simulation. We revealed that the resolidification microstructure is determined by the size and number of Si regions in the initial solidification microstructures and by the threshold size for the nucleation site, depending on the remelting and resolidification conditions. Furthermore, the most refined microstructure with the average grain size of 4.8 µm is predicted to be formed under conditions with a large temperature gradient of Gsol = 106 K/m in the initial solidification, a high heating rate of HR = 105 K/s in the remelting process, and a fast solidification rate of Rresol = 10−1 m/s in the resolidification process. Each of these conditions is necessary to be considered to control the microstructures of Al-Si alloys fabricated via PBF.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Rapid Heating and Cooling Conditions on Microstructure Formation in Powder Bed Fusion of Al-Si Hypoeutectic Alloy: A Phase-Field Study

2022

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“…Certain particles retain their solid state and are dispersed among the fused particles. [58,59] The outcome of this process is the creation of a cladding layer, in which the unfused powders serve as a protective coating for the fused particles. The surface integrity of the built components, as depicted in Figure 9, is significantly influenced by the solidification of the fused particles and the formation of the melt pool.…”

Section: Microstructural Influence Due To Lpmentioning

confidence: 99%

Investigating the Microstructural and Mechanical Characteristics of Laser Additive‐Manufactured AlSi10Mg Specimens Through Experimental and Phase‐Field Modeling Approaches

Panda,

Sahoo,

Kumar

et al. 2024

Adv Eng Mater

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Metal‐based additive manufacturing can make complicated parts that are complex or expensive to cast and process. Rapid cooling rates increase L‐PBF’s mechanical properties during manufacturing. The objective of this study is to examine the impact of process parameters in the L‐PBF technique on the characteristics of microstructure and mechanical properties, specifically, on the nano‐hardness influenced by Si segregation. The microstructures of the produced specimens were examined using FESEM and the analysis identified the existence of bimodal equiaxed α‐Al grains, accompanied by Si phases located within their grain boundaries. In addition, the solidified sample exhibited the segregation of secondary precipitates, particularly , which resulted in enhanced mechanical properties. Both cellular walls and Si precipitates impede the motion and generation of dislocations, thereby influencing the overall behavior of dislocations. The examination of segregation at the top layer was conducted in a comprehensive manner, subsequently employing EDS for analysis. The presence of , , and other phases in all samples was confirmed through XRD. The as‐built samples’ residual stress under different process conditions was also investigated. In addition, a comparison was made between the obtained microstructure and a phase field model that was developed in order to forecast the evolution of the microstructure.This article is protected by copyright. All rights reserved.

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“…Okugawa et al [100] studied the mechanism of grain refinement in the L-PBF additively manufactured high-strength Al-Si hypoeutectic alloy. It was revealed that the Si phase played a crucial role in the refinement of grains in the alloy while the inherent heterogeneous nucleation supported the formation of equiaxed grains adjacent to the fusion lines in the deposited Al alloy [100]. The use of pre-alloyed powders of high-strength alloys for L-PBF was regarded as the most effective approach to maintain the strength of the alloys or age harden the alloys at stress-relieving (heat) treatments between 250°C and 400°C [99].…”

Section: Post-processing Treatments Of Al Alloysmentioning

confidence: 99%

“…Rometsch et al [99] reviewed the latest developments on the L-PBF-produced high-strength Al alloys. Okugawa et al [100] studied the mechanism of grain refinement in the L-PBF additively manufactured high-strength Al–Si hypoeutectic alloy. It was revealed that the Si phase played a crucial role in the refinement of grains in the alloy while the inherent heterogeneous nucleation supported the formation of equiaxed grains adjacent to the fusion lines in the deposited Al alloy [100].…”

Section: Post-processing Treatments Of Al Alloysmentioning

confidence: 99%

Post-processing treatments–microstructure–performance interrelationship of metal additive manufactured aerospace alloys: A review

Ojo

Taban

2023

Materials Science and Technology

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The application of Metal Additive Manufacturing (MAM) in the aerospace industry has been gaining attention. The poor surface quality of parts greatly limits the prospects of MAM-produced parts in the aerospace industry as fatigue performance hinges on a good surface finish and homogeneous microstructure. Post-processing treatments are important to improve the surface quality and the overall performance of MAM-produced parts during static and dynamic loadings. This paper provides a review of the current state of post-processing treatment options for MAM-produced parts. The advances in the post-processing treatments of MAM parts to improve fatigue strength, tensile strength, surface integrity and other properties of parts are reviewed. Future research prospects on metal additive manufacturing of aerospace parts are briefly expounded. Abbreviations: AM: Additive Manufacturing; CMT-WAAM: Cold Metal Transfer-Based Wire Arc Additive Manufacturing; CSD: Cold Spray Deposition; DA: Direct Aging; DED: Directed Energy Deposition; E: Elongation; EBAM: Wire-feed Electron Beam Additive Manufacturing; EBAM Electron Beam Additive Manufacturing; EBSD: Electron Back Scattered Diffraction; FRAM: Friction Rolling Additive Manufacturing; FSAM: Friction Stir Additive Manufacturing; FSP: Friction Stir Processing; HFDB: Hybrid Friction Diffusion Bonding; HIP: Hot Isostatic Pressing; HSA Homogenisation + Solution Treatment + Aging; IFSP: Interlayer Friction Stir Processing; IPF: Inverse Pole Figure; KAM: Kernel Average Misorientation; LAM: Laser Additive Manufacturing Process; LENS: Laser Engineered Net Shaping; LDM: Laser Deposition Manufacturing; L-PBF: Laser Powder Bed Fusion; MAM: Metal Additive Manufacturing; MTFS: Multi-track Multi-layer Friction Surfacing; O-WLAM: Wire Oscillating Laser Additive Manufacturing (O-WLAM); S: Solution Treatment; SA: Solution Treatment + aging; TEM: Transmission Electron Microscope; UAM: Ultrasonic Additive Manufacturing; UTS: Ultimate Tensile Strength; WAAM: Wire Arc Additive Manufacturing; YS: Yield Strength

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Equiaxed grain formation by intrinsic heterogeneous nucleation via rapid heating and cooling in additive manufacturing of aluminum-silicon hypoeutectic alloy

Cited by 28 publications

References 27 publications

Effect of Rapid Heating and Cooling Conditions on Microstructure Formation in Powder Bed Fusion of Al-Si Hypoeutectic Alloy: A Phase-Field Study

Effect of Rapid Heating and Cooling Conditions on Microstructure Formation in Powder Bed Fusion of Al-Si Hypoeutectic Alloy: A Phase-Field Study

Investigating the Microstructural and Mechanical Characteristics of Laser Additive‐Manufactured AlSi10Mg Specimens Through Experimental and Phase‐Field Modeling Approaches

Post-processing treatments–microstructure–performance interrelationship of metal additive manufactured aerospace alloys: A review

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