Thermodynamic modelling of growth-restriction effects in aluminium alloys

Quested, T. E.; Dinsdale, Alan; Greer, A.L.

doi:10.1016/j.actamat.2004.11.024

Cited by 167 publications

(125 citation statements)

References 19 publications

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“…[2]) and based upon an idealized system with straight transus boundaries. [28] Therefore, the implementation of these methods are an idealized approximation to additive manufacturing process, not dissimilar from an idealized approximation of casting.…”

Section: The High Level Of Interest In Additive Manufacturingmentioning

confidence: 99%

Microstructures and Grain Refinement of Additive-Manufactured Ti-xW Alloys

Mendoza

Samimi

Brice

et al. 2017

Metall Mater Trans A

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It is necessary to better understand the composition-processing-microstructure relationships that exist for materials produced by additive manufacturing. To this end, Laser Engineered Net Shaping (LENSä), a type of additive manufacturing, was used to produce a compositionally graded titanium binary model alloy system (Ti-xW specimen (0 £ x £ 30 wt pct), so that relationships could be made between composition, processing, and the prior beta grain size. Importantly, the thermophysical properties of the Ti-xW, specifically its supercooling parameter (P) and growth restriction factor (Q), are such that grain refinement is expected and was observed. The systematic, combinatorial study of this binary system provides an opportunity to assess the mechanisms by which grain refinement occurs in Ti-based alloys in general, and for additive manufacturing in particular. The operating mechanisms that govern the relationship between composition and grain size are interpreted using a model originally developed for aluminum and magnesium alloys and subsequently applied for titanium alloys. The prior beta grain factor observed and the interpretations of their correlations indicate that tungsten is a good grain refiner and such models are valid to explain the grain-refinement process. By extension, other binary elements or higher order alloy systems with similar thermophysical properties should exhibit similar grain refinement.

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Section: The High Level Of Interest In Additive Manufacturingmentioning

confidence: 99%

Microstructures and Grain Refinement of Additive-Manufactured Ti-xW Alloys

Mendoza

Samimi

Brice

et al. 2017

Metall Mater Trans A

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“…SEM was carried out on a Philips 525 FEGSEM with an energy dispersive Xray analysis (EDX) system in un-etched condition. The CALPHAD method was used to predict the phases developed in these alloys using the JMatPro software package (Saunders, 2001) for both equilibrium (Guo et al, 2005;Zhang, Han, & Liu, 2006;Lacaze & Valdes, 2005) and the non-equilibrium Scheil-Gulliver cooling condition (Ohno, Mirkovic, & Schmid-Fetzer, 2006;Quested, Dinsdale, & Greer, 2005). The hardness of the specimens was measured using a standard Rockwell Hardness testing machine in HRF scale with a 60 kg load and using a 1/16" diamond indenter.…”

Section: Methodsmentioning

confidence: 99%

Effects of Copper and Magnesium on Phase Formation Modeling and Mechanical Behavior in AL-CU-MG Alloys

Nafsin¹,

Rashed²

2013

Int J Automot Mech Eng

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The current work emphasizes the establishment of a relationship between microstructure, and copper and magnesium addition in aluminum based alloys. Aluminum alloys containing 4 and 6% copper and 0.50 and 1% magnesium were cast from commercially pure aluminum ingots and homogenized at 400 o C. Images of the microstructures of the as-cast and homogenized alloys were acquired, and image analysis of the phases was performed on the acquired images to obtain area fractions of the phases present in the microstructure. Using the CALPHAD modeling method, thermodynamic modeling of the alloys was carried out in the equilibrium cooling condition since after homogenization for a prolonged time the alloys should reach a close to equilibrium cooling condition. Phase fractions predicted in modeling were matched closely with image analysis data, given that phases present in the homogenized alloys can be interpreted through modeling in the equilibrium cooling condition. EDX analysis of the samples identified the phases present in the alloys as Al 2 Cu, Mg 2 Si and Al 7 Cu 2 Mg. With increasing copper content, it was found both in modeling and experimentally that the amount of Al 2 Cu phase increased, which improved the hardness values of the alloys. However, in the homogenized condition, the hardness values slightly decreased compared to those of the as-cast condition due to retention of a lower fraction of Al 2 Cu phase in the homogenized condition. This was ascertained in the modeling of the alloys. In contrast, Mg 2 Si and Al 7 Cu 2 Mg phases were formed when magnesium was added in the predefined amount; however, these phases were not found to be effective at improving the hardness of the alloys, and the hardness values were barely modified. Apparently, the hardness enhancement after magnesium addition occurred due to a solute effect. To observe the phase effect of magnesium in aluminum alloys, binary alloys of aluminum-magnesium should be cast.

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“…To improve the grain refining efficiency of inoculation, many methods and strategies have been proposed, including chemical modification [3], rapid solidification [4][5][6][7][8], and ultrasonic processing [9], etc. Meanwhile, many theoretical and experimental investigations have aimed at revealing the procedure when inoculants are added to melts [10][11][12][13]. However, the detailed behavior of the interaction of different grain refiners with aluminum melt during grain refining treatment has not yet been fully understood.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cooling Rate on Microstructure and Grain Refining Behavior of In Situ CeB6/Al Composite Inoculant in Aluminum

Liu

Cui

Wang

et al. 2017

Metals

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Abstract:Melt spinning was performed to process an in situ CeB 6 /Al inoculant at different rotating speeds to investigate the influence of cooling rate on the grain refining behavior of inoculants. It has been found that a high cooling rate caused two obvious changes in the inoculant: the supersaturated solid solution of Ce in the α-Al matrix and the miniaturization of CeB 6 particles. At high cooling rates of~10 8 K/s, the Ce content is largely beyond the theoretical solid solubility of Ce in Al, and the size of the CeB 6 particles in ribbons is reduced to~100 nm. The grain refining effect of melt-spun CeB 6 /Al composite inoculant shows significant dependence on holding time of which the best value should be no more than 2 min. The excellent grain refinement of the inoculant can be attributed to the combined effect of the nano-sized refiner particles and the large undercooling caused by the sudden melting of supersaturated Al-Ce solution.

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Thermodynamic modelling of growth-restriction effects in aluminium alloys

Cited by 167 publications

References 19 publications

Microstructures and Grain Refinement of Additive-Manufactured Ti-xW Alloys

Microstructures and Grain Refinement of Additive-Manufactured Ti-xW Alloys

Effects of Copper and Magnesium on Phase Formation Modeling and Mechanical Behavior in AL-CU-MG Alloys

Effect of Cooling Rate on Microstructure and Grain Refining Behavior of In Situ CeB6/Al Composite Inoculant in Aluminum

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