“…This suggests that while the generation of large dislocation densities in rapid solidification is not inherently tied to competitive growth of neighbouring crystals, the shrinkage stresses and the dislocation density distributions are magnified by grain-grain interactions. This stress magnification is consistent with experimental metal additive manufacturing (rapid solidification) of aluminium–copper alloys, where solidification cracking is observed more commonly along grain boundaries [ 22 ]. Figure 8 Phase field–crystal plasticity coupled simulation of Al–4.5at%Cu rapid solidification for all four considered cases, showing the copper concentration, solidification shrinkage induced von Mises stresses, and the densities of statistically stored dislocations.…”
Section: Resultssupporting
confidence: 86%
“…This suggests that while the generation of large dislocation densities in rapid solidification is not inherently tied to competitive growth of neighbouring crystals, the shrinkage stresses and the dislocation density distributions are magnified by grain-grain interactions. This stress magnification is consistent with experimental metal additive manufacturing (rapid solidification) of aluminium-copper alloys, where solidification cracking is observed more commonly along grain boundaries [22].…”
Section: (Ii) Crystal Plasticity Couplingsupporting
confidence: 87%
“…transport industry, where rapid solidification conditions are known to significantly alter the mechanical properties of the material [16,[18][19][20]. In metal additive manufacturing of aluminium alloys, one of the key issues is controlling rapid solidification induced shrinkage and the associated cracking [21,22].…”
Rapid solidification leads to unique microstructural features, where a less studied topic is the formation of various crystalline defects, including high dislocation densities, as well as gradients and splitting of the crystalline orientation. As these defects critically affect the material’s mechanical properties and performance features, it is important to understand the defect formation mechanisms, and how they depend on the solidification conditions and alloying. To illuminate the formation mechanisms of the rapid solidification induced crystalline defects, we conduct a multiscale modelling analysis consisting of bond-order potential-based molecular dynamics (MD), phase field crystal-based amplitude expansion simulations, and sequentially coupled phase field–crystal plasticity simulations. The resulting dislocation densities are quantified and compared to past experiments. The atomistic approaches (MD, PFC) can be used to calibrate continuum level crystal plasticity models, and the framework adds mechanistic insights arising from the multiscale analysis.
This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’.
“…This suggests that while the generation of large dislocation densities in rapid solidification is not inherently tied to competitive growth of neighbouring crystals, the shrinkage stresses and the dislocation density distributions are magnified by grain-grain interactions. This stress magnification is consistent with experimental metal additive manufacturing (rapid solidification) of aluminium–copper alloys, where solidification cracking is observed more commonly along grain boundaries [ 22 ]. Figure 8 Phase field–crystal plasticity coupled simulation of Al–4.5at%Cu rapid solidification for all four considered cases, showing the copper concentration, solidification shrinkage induced von Mises stresses, and the densities of statistically stored dislocations.…”
Section: Resultssupporting
confidence: 86%
“…This suggests that while the generation of large dislocation densities in rapid solidification is not inherently tied to competitive growth of neighbouring crystals, the shrinkage stresses and the dislocation density distributions are magnified by grain-grain interactions. This stress magnification is consistent with experimental metal additive manufacturing (rapid solidification) of aluminium-copper alloys, where solidification cracking is observed more commonly along grain boundaries [22].…”
Section: (Ii) Crystal Plasticity Couplingsupporting
confidence: 87%
“…transport industry, where rapid solidification conditions are known to significantly alter the mechanical properties of the material [16,[18][19][20]. In metal additive manufacturing of aluminium alloys, one of the key issues is controlling rapid solidification induced shrinkage and the associated cracking [21,22].…”
Rapid solidification leads to unique microstructural features, where a less studied topic is the formation of various crystalline defects, including high dislocation densities, as well as gradients and splitting of the crystalline orientation. As these defects critically affect the material’s mechanical properties and performance features, it is important to understand the defect formation mechanisms, and how they depend on the solidification conditions and alloying. To illuminate the formation mechanisms of the rapid solidification induced crystalline defects, we conduct a multiscale modelling analysis consisting of bond-order potential-based molecular dynamics (MD), phase field crystal-based amplitude expansion simulations, and sequentially coupled phase field–crystal plasticity simulations. The resulting dislocation densities are quantified and compared to past experiments. The atomistic approaches (MD, PFC) can be used to calibrate continuum level crystal plasticity models, and the framework adds mechanistic insights arising from the multiscale analysis.
This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’.
“…Thus, this review differs from other similar articles such as [29][30][31]. Additionally, there are also other reviews that cover various aspects of these LPBF alloys such as [32][33][34][35][36][37][38][39][40][41][42][43] for Ti-6Al-4 V, [32,33,[44][45][46][47] for Inconel 718, [32-37, 48, 49] for AISI 316L and [33,[50][51][52][53][54][55][56] for AlSi10Mg.…”
Laser powder bed fusion (LPBF) is an emerging additive manufacturing technique that is currently adopted by a number of industries for its ability to directly fabricate complex near-net-shaped components with minimal material wastage. Two major limitations of LPBF, however, are that the process inherently produces components containing some amount of porosity and that fabricated components tend to suffer from poor repeatability. While recent advances have allowed the porosity level to be reduced to a minimum, consistent porosity-free fabrication remains elusive. Therefore, it is important to understand how porosity affects mechanical properties in alloys fabricated this way in order to inform the safe design and application of components. To this aim, this article will review recent literature on the effects of porosity on tensile properties, fatigue life, impact and fracture toughness, creep response, and wear behavior. As the number of alloys that can be fabricated by this technology continues to grow, this overview will mainly focus on four alloys that are commonly fabricated by LPBF—Ti-6Al-4 V, Inconel 718, AISI 316L, and AlSi10Mg.
“…One of the most promising technologies from this point of view is electron beam additive manufacturing (EBAM) of large-sized products, which is based on the principle of metal wire melting in a molten pool. This method is very effective in producing high-quality components of different materials: titanium alloys [3,4], steels [5], copper alloys [6], aluminum alloys [7,8] and bimetallic products [9]. However, the products fabricated by the additive manufacturing method often require additional treatments to improve the structure and mechanical properties.…”
Friction stir processing of additive workpieces in the sample growth direction (the vertical direction) and the layer deposition direction (the horizontal one) was carried out. The hardening regularities of aluminum-silicon alloy A04130 and aluminum-magnesium alloy AA5056 manufactured by electron beam additive technology were studied. For each material, 1 to 4 subsequent tool passes were performed in both cases. It was found that the formation of the stir zone macro-structure does not significantly change with the processing direction relative to the layer deposition direction in additive manufacturing. The average grain size in the stir zone after the fourth pass for AA5056 alloy in the horizontal direction was 2.5 ± 0.8 μm, for the vertical one, 1.6 ± 0.5 μm. While for the alloy A04130, the grain size was 2.6 ± 1.0 μm and 1.8 ± 0.7 for the horizontal and vertical directions, respectively. The fine-grained metal of the stir zone for each alloy in different directions had higher microhardness values than the base metal. The tensile strength of the processed metal was significantly higher than that of the additively manufactured material of the corresponding alloy. The number of tool passes along the processing line is different for the two selected alloys. The second, third and fourth passes have the most significant effect on the mechanical properties of the aluminum-magnesium alloy.
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