Grain refinement of Mg–Al(–Mn) alloys by SiC additions

Easton, Mark; Schiffl, Andreas; Yao, Ji Yong; Kaufmann, Helmut

doi:10.1016/j.scriptamat.2006.04.014

Cited by 121 publications

(91 citation statements)

References 11 publications

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“…Experimental studies have produced a large amount of data relating grain size with various solute based parameters 27,30,[32][33][34][44][45][46][47][48][49][50][51][52][53] . It is fortunate that what is a complex relationship between grain size and alloy composition 36,38,54 can be in the first instance related to some simple parameters.…”

Section: Constitutional Supercooling and The Supercooling Parametmentioning

confidence: 99%

Grain Refinement of Al-Si Hypoeutectic Alloys by Al3Ti1B Master Alloy and Ultrasonic Treatment

Gui

Wang

Prasad

et al. 2016

Shape Casting: 6th International Symposium

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The concept of constitutional supercooling (CS) including the term itself was first described and discussed qualitatively by in order to understand the formation of cellular structures during the solidification of tin, and then quantified by Tiller, Jackson, Rutter, and Chalmers (1953). On that basis, Winegard and Chalmers (1954) further considered 'supercooling and dendritic freezing of alloys' where they described how CS promotes the heterogeneous nucleation of new crystals and the formation of an equiaxed zone. Since then the importance of CS in promoting the formation of equiaxed microstructures in both grain refined and unrefined alloys has been clearly revealed and quantified. This paper describes our current understanding of the role of CS in promoting nucleation and grain formation. It also highlights that CS, on the one hand, develops a nucleation-free zone surrounding each nucleated and growing grain and, on the other hand, protects this grain from readily remelting when temperature fluctuations occur due to convection. Further, due to the importance of the diffusion field that generates CS recent analytical models are evaluated and compared with a numerical model. A comprehensive description of the mechanisms affecting nucleation and grain formation and the prediction of grain size is presented with reference to the influence of the casting conditions applied during the practical casting of an alloy.

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Section: Constitutional Supercooling and The Supercooling Parametmentioning

confidence: 99%

Grain Refinement of Al-Si Hypoeutectic Alloys by Al3Ti1B Master Alloy and Ultrasonic Treatment

Gui

Wang

Prasad

et al. 2016

Shape Casting: 6th International Symposium

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“…Grain refinement by inoculation with chemical grain refiners is an important and effective approach for mitigating such problems [3,4]. Although grain refinement of magnesium alloys has attracted intensive research [2,[5][6][7] the search for new and effective grain refiners, and methods for grain refinement still continues. Contemporary research on grain refinement of magnesium alloys has mainly focused on searching and developing new chemical grain refiners and on the application of external physical fields including electromagnetic and ultrasonic fields, for example [8].…”

Section: Introductionmentioning

confidence: 99%

Grain refinement of DC cast magnesium alloys with intensive melt shearing

Zuo¹,

Jiang²,

Zhang³

et al. 2012

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract.A new direct chill (DC) casting process, melt conditioned DC (MC-DC) process, has been developed for the production of high quality billets/slabs of light alloys by application of intensive melt shearing through a rotor-stator high shear device during the DC casting process. The rotor-stator high shear device provides intensive melt shearing to disperse the naturally occurring oxide films, and other inclusions, while creating a microscopic flow pattern to homogenize the temperature and composition fields in the sump. In this paper, we report the grain refining effect of intensive melt shearing in the MC-DC casting processing. Experimental results on DC casting of Mg-alloys with and without intensive melt shearing have demonstrated that the MC-DC casting process can produce magnesium alloy billets with significantly refined microstructure. Such grain refinement in the MC-DC casting process can be attributed to enhanced heterogeneous nucleation by dispersed naturally occurring oxide particles, increased nuclei survival rate in uniform temperature and compositional fields in the sump, and potential contribution from dendrite arm fragmentation. IntroductionMagnesium alloys have low density, high specific strength, high damping capacity, good castability and excellent electromagnetic shielding properties, which make them suitable for applications in many industrial sectors including automotive, aerospace, defence, electronics, healthcare, and sports equipment [1,2]. DC casting is a key technology for providing billets or slabs of magnesium alloys. However, the billets or slabs made by the conventional DC casting process often have coarse and nonuniform microstructures, severe chemical segregation, porosity, and hot tearing, which not only burden downstream thermo-mechanical processing, but also have a negative influence on the mechanical properties of the final products. Grain refinement by inoculation with chemical grain refiners is an important and effective approach for mitigating such problems [3,4]. Although grain refinement of magnesium alloys has attracted intensive research [2,[5][6][7] the search for new and effective grain refiners, and methods for grain refinement still continues. Contemporary research on grain refinement of magnesium alloys has mainly focused on searching and developing new chemical grain refiners and on the application of external physical fields including electromagnetic and ultrasonic fields, for example [8]. Recently, Fan and his co-workers [9][10][11][12] have found that the intensive melt shearing provided by a twin-screw mechanism has a significant grain refining effect on both aluminium and magnesium alloys. Based on a similar principle, a rotor-stator high shear device for intensive melt shearing has been developed [13]. In the present work, melt conditioned DC (MC-DC) casting by combining the conventional DC casting with the rotor-stator high shear device was used for the production of high quality magnesium alloy billets. This paper presents our experimental

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“…In the recent past extensive research has been focused on developing new grain refiner for magnesium cast alloys, and a number of grain refiners have been reported, such as zirconium for magnesium alloys which do not contain elements such as aluminum, manganese and silicon, since zirconium forms stable compounds with these elements [5] and Al 4 C 3 [47,48], SiC [49,50] or by carbon inoculation [51,52] for aluminum bearing magnesium alloy. Although the dependence of grain refining efficiency at different addition level of inoculated particles has been investigated [53,54] there is still lack of experimental data on the role of the active particles in grain refinement.…”

Section: Introductionmentioning

confidence: 99%

An Analysis of the Grain Refinement of Magnesium by Zirconium

Saha

Viswanathan

2011

Magnesium Technology 2011

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A Design of Experiments (DOE) approach was used to conduct a systematic study of the grain refinement of magnesium by zirconium; variables included the amount of zirconium, the pouring temperature, and the settling time prior to casting. Samples were poured into a special "hockey puck" mold designed to reproduce the conditions in permanent mold casting. Optical and scanning electron microscopy (SEM) was utilized to measure the grain size in the final microstructure. Sample dissolution followed by SEM was used to characterize zirconium particle size and morphology both in the master alloy and grain refined samples, while an AccuSizer 770 Photozone/Light Obscuration instrument was used to measure total particle size distributions in the master alloy and grain refined samples. Transmission Electron Microscopy (TEM) was used to identify particles that likely act as suitable heterogeneous nucleation sites for grain refinement.The TEM results show that a range of particle sizes are likely substrates and that only zirconium particles which are faceted are likely nucleation sites. It is apparent that only 1 to 3% of the total particles serve as nucleation sites, but a comparison of the grain density vs. faceted particle density shows close agreement. Equal Channel Angular Extrusion (ECAE) processing of the magnesium-15wt% zirconium master alloy to increase the number of faceted particles resulted in improved grain refinement efficacy. This work suggests that there is a tremendous potential to engineer a more efficient grain refiner.iii

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Grain refinement of Mg–Al(–Mn) alloys by SiC additions

Cited by 121 publications

References 11 publications

Grain Refinement of Al-Si Hypoeutectic Alloys by Al3Ti1B Master Alloy and Ultrasonic Treatment

Grain Refinement of Al-Si Hypoeutectic Alloys by Al3Ti1B Master Alloy and Ultrasonic Treatment

Grain refinement of DC cast magnesium alloys with intensive melt shearing

An Analysis of the Grain Refinement of Magnesium by Zirconium

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