Oxide film characteristics of AZ91 magnesium alloy in casting conditions

Mirak, Alireza; Divandari, M.; Boutorabi, S. M. A.; Campbell, John B.

doi:10.1179/136404607x256042

Cited by 51 publications

(26 citation statements)

References 12 publications

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“…When the velocity exceeds 0.32 m s −1 , there is a significant turbulence in the melt entering the mould. This confirms the work carried out by Bahreinian et al (2006) and Mirak et al (2007).…”

Section: Resultssupporting

confidence: 90%

“…As a deterrent force, the friction, surface tension and temperature of the melt can be pointed. The special mode of moving of the melt has been reported by some researches on AZ91 (Mirak et al, 2007) and Al alloys (Montazerin and Boutorabi, 1998).…”

Section: Resultsmentioning

confidence: 78%

“…Previous investigations show that inclusions reduce the melt fluidity and increase the possibility of gas porosity formation (Campbell, 2003;Mirak et al, 2007). Finally these defects reduce mechanical properties, corrosion resistance and machinability considerably (Tian et al, 2002).…”

Section: Introductionmentioning

confidence: 95%

“…When the Mg alloy is poured, the freshly created surface oxidizes and creates oxide in the bulk of the molten alloy. This occurs by a folding process in which a double film is created and characterized by a dry surface contact (Mirak et al, 2007;Bahreinian et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Effect of filtration on the morphology and mechanical properties of Mg molten alloy entering the mould cavity

Nazari

Razavi

Boutorabi

2010

Journal of Materials Processing Technology

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of filtration on the morphology and mechanical properties of Mg molten alloy entering the mould cavity

Nazari

Razavi

Boutorabi

2010

Journal of Materials Processing Technology

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“…As a consequence of this intensive melt shearing the clusters of inclusions and oxide films naturally occurring in the melt will be dispersed into individual particles [9]. It is well documented that naturally occurring oxide films are hazardous to casting processes, and more importantly they deteriorate mechanical properties of the final cast products [14,15]. In the MC-DC process, the intensive melt shearing makes the usually harmful oxide films and other inclusions not only harmless, but also useful for grain refinement.…”

Section: Discussionmentioning

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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