Settling of undissolved zirconium particles in pure magnesium melts

Qian, Ma; Zheng, Lanqin; Graham, D.A.; Frost, M. T.; StJohn, David H.

doi:10.1016/s1471-5317(01)00009-8

Cited by 84 publications

(36 citation statements)

References 6 publications

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“…Due to their density (much higher than those of the Mg melt) they settle and deposit at the bottom of the ingots. Secondly, if Zr is not reacting with alloying elements or impurities it forms metallic Zr particles in a peritectic reaction during solidification or holding at the given temperatures [42,43]. Zr has a density of 6.5 g cm -3 .…”

Section: Chemical Compositionsmentioning

confidence: 99%

“…Mg alloys have attracted much attention for their potential use in medical applications due to the low Young's modulus (40)(41)(42)(43)(44)(45) GPa) compared with Ti alloys (Ti6Al4V, 114 GPa) and stainless steels (193 GPa), appropriate strength compared to bone, good biodegradability and bioresorbability [1][2][3]. Even though Mg and its alloys have been investigated as implants for almost two centuries, implants of Mg and its alloys are yet to be commercialized.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure, mechanical and corrosion properties of Mg–Dy–Gd–Zr alloys for medical applications

et al. 2013

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In previous investigations Mg-10Dy (wt.%) alloy with a good combination of corrosion resistance and cytocompatibility showed a great potential for the use as biodegradable implant material. However, the mechanical properties of Mg-10Dy alloy are not satisfactory. In order to allow the tailoring of mechanical properties required for various medical applications, four Mg-10(Dy+Gd)-0.2Zr (wt.%) alloys were investigated with respect to microstructure, mechanical and corrosion properties.With the increase of Gd content, the amount of second phase particles increased in the as-cast alloys and the age hardening response increased at 200 °C. The yield strength increased while the ductility reduced especially for peak-aged alloys with the addition of Gd. Additionally, with increasing Gd content, the corrosion rate increased in the as-cast condition due to galvanic effect, but all the alloys have a similar corrosion rate (about 0.5 mm/year) in solution treated and aged condition.

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Section: Chemical Compositionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microstructure, mechanical and corrosion properties of Mg–Dy–Gd–Zr alloys for medical applications

et al. 2013

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“…Either can cause an increase in the average grain size of the final alloy. [34,35] The soluble Zr content in a magnesium alloy is also affected by the alloy composition; e.g., it has been found that the soluble Zr content is a function of the Zn content in Mg-Zn alloys and Zn and Zr form stable intermetallic compounds when the Zn content exceeds about 4 pct. [36] A detailed examination of the size distribution of active zirconium particles that were observed at the centers of Zr-rich cores, in a fully grain-refined magnesium alloy, showed that the majority of particles were in the range between 1 and 5 m in size when measured on polished sections, and that the most active group of particles were ϳ2 m when solidified in a mild steel cone mold.…”

Section: B Grain Refinement Of Magnesium Alloys By Zrmentioning

confidence: 99%

Grain refinement of magnesium alloys

StJohn

Qian

Easton

et al. 2005

Metall Mater Trans A

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619

389

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The literature on grain refinement of magnesium alloys is reviewed with regard to two broad groups of alloys: alloys that contain aluminum and alloys that do not contain aluminum. The alloys that are free of aluminum are generally very well refined by Zr master alloys. On the other hand, the understanding of grain refinement in aluminum bearing alloys is poor and in many cases confusing probably due to the interaction between impurity elements and aluminum in affecting the potency of nucleant particles. A grain refinement model that was developed for aluminum alloys is presented, which takes into account both alloy chemistry and nucleant particle potency. This model is applied to experimental data for a range of magnesium alloys. It is shown that by using this analytical approach, new information on the refinement of magnesium alloys is obtained as well as providing a method of characterizing the effectiveness of new refiners. The new information revealed by the model has identified new directions for further research. Future research needs to focus on gaining a better understanding of the detailed mechanisms by which refinement occurs and gathering data to improve our ability to predict grain refinement for particular combinations of alloy and impurity chemistry and nucleant particles.

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“…[13] Additionally, when the melt cools from the alloying or remelt temperature to the peritectic temperature (653.56°C), Zr particles could precipitate from the melt as the solubility decreases. Hence, there is Zr dissolved in the melt and there are also Zr particles (undissolved Zr) floating in the melt at the peritectic temperature.…”

Section: E Analysis Of the Dissolved Zr Contentmentioning

confidence: 99%

The Loss of Dissolved Zirconium in Zirconium-Refined Magnesium Alloys after Remelting

Qian

Hildebrand

StJohn

2009

Metall Mater Trans A

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Magnesium-rare earth-zirconium (Mg-RE-Zr) materials are a high value-added class of speciality alloys used chiefly for aerospace applications, where the use of zirconium ensures the critically needed structural uniformity and consistency in performance through potent grain refinement. However, the manufacture of these alloy components has proved to be problematic and volatile. A viable approach preferred by manufacturers is to simply remelt fully grainrefined prealloyed ingot materials and cast. Unfortunately, the dissolved Zr content in these alloys decreases appreciably after remelting, leading to significantly increased grain sizes and inhomogeneity. This work investigates the mechanisms responsible for the loss of dissolved Zr in Zr-refined magnesium alloys after remelting. It was revealed that the phenomenon stems from the unique Zr-rich cores existing in these alloys. Precipitation of zirconium from these supersaturated cores during heating reduces the dissolved Zr content in the a-Mg phase. On the other hand, once precipitated out, the zirconium precipitates show very limited dissolution in molten magnesium due to their discontinuous dissolution behavior in the absence of agitation. The loss of dissolved Zr was found to be reversible by agitation when remelted in an iron-free environment while irreversible in steel crucibles due to the interference from iron.

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Settling of undissolved zirconium particles in pure magnesium melts

Cited by 84 publications

References 6 publications

Microstructure, mechanical and corrosion properties of Mg–Dy–Gd–Zr alloys for medical applications

Microstructure, mechanical and corrosion properties of Mg–Dy–Gd–Zr alloys for medical applications

Grain refinement of magnesium alloys

The Loss of Dissolved Zirconium in Zirconium-Refined Magnesium Alloys after Remelting

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