Discussions on grain refinement of magnesium alloys by carbon inoculation

Qian, Ma; Cao, Peng

doi:10.1016/j.scriptamat.2004.10.014

Cited by 133 publications

(104 citation statements)

References 8 publications

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“…44,51) For the case of weak bonding at the interface, interfacial slip may occur when the magnitude of the shear stress at the interface is sufficient to overcome frictional loads. In the present composites, the formation of the Al 4 C 3 phase observed in Al/C 60 composites processed by squeeze casting, 10) and the Al 4 C 3 or Al-C-O phases observed in carbon inoculated AZ91 alloy [52][53][54] may not be possible. This is because the processing temperature for the present study was low.…”

Section: Discussionmentioning

confidence: 60%

Mechanical and Damping Properties of Fullerene-Dispersed AZ91 Magnesium Alloy Composites Processed by a Powder Metallurgy Route

et al. 2006

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The microstructures and mechanical properties of fullerene powder dispersed AZ91 magnesium alloy composites were examined. The AZ91 with 0, 1 and 5 mass% fullerene additions were produced by extruding a mixture of AZ91 machined chips and fullerene powder. The matrix grains of the extruded materials were equiaxed, and the size was $ 5 mm irrespective of the fullerene content. The agglomerated fullerene powder was aligned parallel to the extrusion direction in the composites. The addition of 1 mass% fullerene had little effect on the elastic moduli, tensile strength and ductility, whereas the addition of 5 mass% fullerene slightly decreased them. A comparison between the tensile properties of the present composites and those of AZ91 alloys processed by various methods was also made. The damping capacity increased steeply by the fullerene addition. The effectiveness of the fullerene addition for the enhancement of the damping capacity of metallic alloys was verified. A good combination of damping capacity, elastic moduli, strength and ductility was attained in the present composites.

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Section: Discussionmentioning

confidence: 60%

Mechanical and Damping Properties of Fullerene-Dispersed AZ91 Magnesium Alloy Composites Processed by a Powder Metallurgy Route

et al. 2006

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“…The structure is entirely composed of equiaxed grains with an average grain size of 490 mm. Considering the cast structure of pure magnesium is essentially composed of columnar grains, 17,18) lanthanum exerted some degree of grain refinement effect to magnesium casting. The degree of grain refinement effect of solute elements has been correlated by StJohn et al 19) in terms of grain growth restriction factor (GRF), which is an indicator of the initial rate of development of constitutional undercooling and expressed as m i C o ðk i À 1Þ, where m i is the slope of liquidus line, C o is the initial concentration of element i, and k i is the equilibrium distribution coefficient.…”

Section: Resultsmentioning

confidence: 99%

Effects of Lanthanum and Zirconium on Cast Structure and Room Temperature Mechanical Properties of Mg-La-Zr Alloys

et al. 2011

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Cast Mg-La and Mg-La-Zr alloy ingots were prepared from 99.96% magnesium and 99.9% lanthanum with a zirconium addition made using a Mg-33Zr master alloy. The microstructure was examined and tensile tests performed for the cast alloys. Lanthanum showed a mild grain refinement effect on magnesium, generating coarse equiaxed grains in the casting. The microstructure within the equiaxed grain contained the primary Mg dendrites and degenerated lamellar eutectic in the interdendritic regions. An addition of zirconium to the Mg-La alloys transformed coarse primary -Mg dendrites into fine globular grains surrounded by eutectic regions. With this change tensile properties improved significantly in comparison with the binary Mg-La alloys of comparative lanthanum content. The hardness value increased linearly with lanthanum content due to an increase in the eutectic Mg 12 La phase. Fracture occurred owing to the decohesion between the primary Mg grains and eutectic Mg 12 La phases. An increase in the eutectic regions thus leads to a reduction in ductility by means of crack propagation through the regions.

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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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Discussions on grain refinement of magnesium alloys by carbon inoculation

Cited by 133 publications

References 8 publications

Mechanical and Damping Properties of Fullerene-Dispersed AZ91 Magnesium Alloy Composites Processed by a Powder Metallurgy Route

Mechanical and Damping Properties of Fullerene-Dispersed AZ91 Magnesium Alloy Composites Processed by a Powder Metallurgy Route

Effects of Lanthanum and Zirconium on Cast Structure and Room Temperature Mechanical Properties of Mg-La-Zr Alloys

An Analysis of the Grain Refinement of Magnesium by Zirconium

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