Phase Formation during Solidification of Mg-Nd-Zn Alloys: An In Situ Synchrotron Radiation Diffraction Study

Tolnai, D.; Subroto, Tungky; Gavras, Sarkis; Buzolin, Ricardo Henrique; Stark, Andreas; Schell, Norbert; Hort, Norbert

doi:10.3390/ma11091637

Cited by 5 publications

(6 citation statements)

References 27 publications

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“…The liquidus temperature of Elektron 21 is ≈640 °C with a solidification range of 120 °C. [ 15 ] The first slice depicts an already advanced state of dendritic solidification approximately at a temperature of 620 °C. The images before this state cannot be properly reconstructed and segmented due to the movement of dendrites being fast when compared with the acquisition time for a full tomogram and due to the poor contrast between the dendrites and the melt at the onset of solidification.…”

Section: Resultsmentioning

confidence: 99%

In Situ Synchrotron Tomography of the Solidification of an Elektron 21 Mg Alloy

et al. 2021

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The directional solidification of an Elektron 21 magnesium alloy is investigated by in situ synchrotron radiation tomography. To visualize the solidification process, samples of Elektron 21 are first heated to 800 °C, and the melt is held at this temperature for 5 min, to ensure temperature homogeneity. Subsequently, the samples are cooled with a cooling rate of 10 K min−1, while for every 35 s, one full tomogram is acquired. The evolution of the microstructure can be followed in 3D on the reconstructed tomograms. The contrast between rare‐earth metals and Mg enables to quantitatively analyze the changes in the morphology of the dendritic structure during solidification. At the onset of the detection, the growth of secondary dendrite arms occurs, which ends at the dendritic coherency point. From this temperature on, only the coarsening and coalescence of existing dendrite arms occurs.

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Section: Resultsmentioning

confidence: 99%

In Situ Synchrotron Tomography of the Solidification of an Elektron 21 Mg Alloy

et al. 2021

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Section: Alloy Developmentmentioning

confidence: 99%

“…Moreover, the phase evolution dependent on increasing addition of certain alloying elements to binary alloys can be studied, such as Zn (3, 5, and 8 wt%) to Mg–4Nd. [ 67 ] Tolnai et al found that Mg 5 Nd 8 Zn 42 phases were present for 5 and 8 wt% Zn and Mg 3 (Nd,Zn) for all alloys with Zn addition. The experimentally observed phases differed somewhat from those predicted using thermodynamic calculations, thus the data could be used to improve the underlying databases.…”

Section: Alloy Developmentmentioning

confidence: 99%

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Utilizing Synchrotron Radiation for the Characterization of Biodegradable Magnesium Alloys—From Alloy Development to the Application as Implant Material

et al. 2021

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Magnesium (Mg)-based alloys are investigated for the use as lightweight structural metals, e.g., in the automotive industry, [1] as biodegradable implant materials [2] and for hydrogen storage. [3] The choice of alloying system and subsequent processing of the material is a crucial factor for the degradation profile of the alloy and its mechanical properties. [4][5][6][7] This review focuses on use of Mg alloys as implant material, with some references to its application as a structural metal.The degradation profile of Mg alloys is of particular importance for their application as implant materials, as a controlled degradation is required to ensure cell viability and implant stability in vivo. [8,9] During the development of Mg alloys for the application as a biodegradable implant, alloying systems are carefully selected and manufactured, with their microstructure being tailored according to specifications by selecting the appropriate processing route. The microstructure and the mechanical properties of the alloy will be evaluated and the alloy is then tested for in vitro degradation in an aqueous environment under physiological conditions (pH %7.4, 37 C, 5% CO 2 , 21% O 2 , 95% rel. humidity) with and without cells to assess its general degradation properties and cell viability. [10] The mechanical properties and degradation profile need to be tailored depending on the application of the implant. Mg alloys for bone support, for example, require mechanical properties close to that of bone. For bone, the average Young's modulus is between 7 and 31 GPa, depending on the type of bone and its hydration state. [11,12] In longitudinal direction, the bone's tensile and compressive ultimate strength have been reported to be between 93 and 135 MPa, and 154 and 205 MPa, respectively. [13,14] Finally, the elongation to failure of the clinically approved MAGNEZIX screw by Syntellix AG (Hanover, Germany) was determined to be 8%. [15] By contrast, Mg alloys designed for the use as stents must possess a minimum ultimate tensile strength of 300 MPa, low yield strength of 200-300 MPa, and higher ductility (min. 15%-18% elongation to failure, preferably 30%) for their successful deployment. [16,17] Finally, in vivo animal experiments are conducted to evaluate the alloy suitability for the translation into the clinic.

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“…However, under realistic casting conditions, the Mg 12 Nd metastable phase is formed [12]. Given that the presence of Zn stabilizes the metastable Mg 3 (Nd, Zn) phase [13], extensive research has been recently devoted to the Mg–Nd–Zn system, aiming to characterize the mechanical behavior of the alloys at ambient and elevated temperatures under different load conditions and fatigue [9]. Because Nd is also biocompatible, these alloys are considered to be prospective implant materials for future medical applications [14].…”

Section: Introductionmentioning

confidence: 99%

In Situ Synchrotron Diffraction Analysis of Zn Additions on the Compression Properties of NK30

et al. 2019

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In situ synchrotron radiation diffraction was performed during the compression of as-cast Mg–3Nd–Zn alloys with different amounts (0, 0.5, 1, and 2 wt %) of Zn addition at room temperature. During the tests, the acoustic emission signals of the samples were recorded. The results show that the addition of Zn decreased the strength of the alloys but, at the same time, increased their ductility. In the earlier stages of deformation, twin formation and basal slip were the dominant deformation mechanisms. The twins tended to grow during the entire compression stage; however, the formation of new twins dominated only at the beginning of the plastic deformation. In order to accommodate the strain levels, the alloys containing Zn underwent nonbasal slip in the later stages of deformation. This can be attributed to the presence of precipitates containing Zn in the microstructure, inhibiting twin growth.

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Phase Formation during Solidification of Mg-Nd-Zn Alloys: An In Situ Synchrotron Radiation Diffraction Study

Cited by 5 publications

References 27 publications

In Situ Synchrotron Tomography of the Solidification of an Elektron 21 Mg Alloy

In Situ Synchrotron Tomography of the Solidification of an Elektron 21 Mg Alloy

Utilizing Synchrotron Radiation for the Characterization of Biodegradable Magnesium Alloys—From Alloy Development to the Application as Implant Material

In Situ Synchrotron Diffraction Analysis of Zn Additions on the Compression Properties of NK30

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