Effects of Mg content on primary Mg2Si phase in hypereutectic Al–Si alloys

In order to investigate the effect of Mg2Si formation on the microstructure and properties of an Al−Si alloy, the critical point of a hypereutectic Al−17Si−4Cu−Mg alloy was calculated by Pandat software. The calculation results of the equilibrium phase diagram show that the critical point for Mg2Si phase formation for the alloy was obtained when the Mg content was 2.2%. The contents of 0.5 wt.% Mg and 2.5 wt.% Mg were selected as the research object. The content of Mg increased from 0.5 wt.% to 2.5 wt.%, the eutectic Si in the matrix was reduced, and the Chinese character-like Mg2Si phase appeared in the microstructure. In the peak ageing state, in addition to θ” and Q’ phases that were mainly precipitated, there was also needle-like β” precipitation in the 2.5 wt.% Mg content alloy. Larger precipitates were found in 2.5 wt.% content alloys, mainly due to the promotion of the solid solution having the aggregation and segregation of more solute elements in the matrix. The tensile strength, elongation, and hardness of hypereutectic Al−17Si−4Cu−0.5Mg alloy under peak ageing were 331 MPa, 3.11%, and 152.1 HB, respectively. The tensile strength and the elongation decreased while the hardness increased with the 2.5 wt.% Mg content, which is due to the formation of hard and brittle Mg2Si and Al8FeMg3Si, which has a splitting effect on the matrix.

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Influence of barium addition on the formation of primary Mg2Si crystals from Al–Mg–Si melts

Journal of Materials Research and Technology ◽

10.1016/j.jmrt.2021.01.051 ◽

2021 ◽

Vol 11 ◽

pp. 448-465

Author(s):

Hamidreza Ghandvar ◽

Kadhim A. Jabbar ◽

Mohd Hasbullah Idris ◽

Norhayati Ahmad ◽

Muhammad Hafiz Jahare ◽

...

Keyword(s):

Primary Mg2si

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DC and AC Conductivity, Biosolubility and Thermal Properties of Mg-Doped Na2O–CaO–P2O5 Glasses

Materials ◽

10.3390/ma14102626 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2626

Author(s):

Natalia Anna Wójcik ◽

Sharafat Ali ◽

Jakub Lech Karczewski ◽

Bo Jonson ◽

Michał Bartmański ◽

...

Keyword(s):

Thermal Properties ◽

Saline Solution ◽

Glass Structure ◽

Glass Network ◽

Bioactive Glasses ◽

Dc And Ac Conductivity ◽

Impedance Spectroscopy Technique ◽

Mg Content ◽

Phosphate Buffered Saline ◽

Mg Doped

Bioactive glasses have recently been extensively used to replace, regenerate, and repair hard tissues in the human body because of their ability to bond with living tissue. In this work, the effects of replacing Na2O with MgO on the electrical, biosolubility, and thermal properties of the target glass 10Na2O–60P2O5–30CaO (in mol%) were investigated. The electrical properties of the glasses were studied with the impedance spectroscopy technique. At 473 K, DC conductivity values decreased from 4.21 × 10−11 to 4.21 × 10−12 S cm−1 after complete substitution of MgO for Na2O. All samples had a similar activation energy of the DC conduction process ~1.27 eV. Conduction mechanisms were found to be due to hop of ions: Na+, Mg2+, and probable H+. FTIR analysis showed that, as the Mg content increased, the Q2 unit (PO2−) shifted towards higher wavenumbers. The proportion of Q3 unit (P2O5) decreased in the glass structure. This confirmed that the replacement of Na+ by Mg2+ was accompanied by concurrent polymerization of the calcium–phosphate glass network. The biosolubility test in the phosphate-buffered saline solution showed that the magnesium addition enhanced the biosolubility properties of Na2O–CaO–P2O5 glasses by increasing their dissolution rate and supporting forming CaP-rich layers on the surface. The glass transition temperature increased, and thermal stability decreased substantially upon substitution of Na2O by MgO.

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Novel Nickel- and Magnesium-Modified Cenospheres as Catalysts for Dry Reforming of Methane at Moderate Temperatures

Catalysts ◽

10.3390/catal9121066 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1066 ◽

Cited By ~ 2

Author(s):

Bogdan Samojeden ◽

Marta Kamienowska ◽

Armando Izquierdo Colorado ◽

Maria Elena Galvez ◽

Ilona Kolebuk ◽

...

Keyword(s):

Supported Catalysts ◽

Temperature Programmed Desorption ◽

Catalytic Performance ◽

Dry Reforming ◽

Dry Reforming Of Methane ◽

Temperature Programmed Reduction ◽

Fly Ashes ◽

Coal Fly Ashes ◽

Temperature Programmed ◽

Mg Content

Cenospheres from coal fly ashes were used as support in the preparation of Ni–Mg catalysts for dry reforming of methane. These materials were characterized by means of XRD, H2-temperature-programmed reduction (H2-TPR), CO2-temperature-programmed desorption (CO2-TPD), and low-temperature nitrogen sorption techniques. The cenosphere-supported catalysts showed relatively high activity and good stability in the dry reforming of methane (DRM) at 700 °C. The catalytic performance of modified cenospheres was found to depend on both Ni and Mg content. The highest activity at 750 °C and 1 atm was observed for the catalyst containing 30 wt % Mg and 10, 20, and 30 wt % Ni, yielding to CO2 and CH4 conversions of around 95%.

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Effects of Thermal Annealing on the Properties of Zirconium-Doped MgxZn1−XO Films Obtained through Radio-Frequency Magnetron Sputtering

Membranes ◽

10.3390/membranes11050373 ◽

2021 ◽

Vol 11 (5) ◽

pp. 373

Author(s):

Wen-Yen Lin ◽

Feng-Tsun Chien ◽

Hsien-Chin Chiu ◽

Jinn-Kong Sheu ◽

Kuang-Po Hsueh

Keyword(s):

Magnetron Sputtering ◽

Radio Frequency ◽

Photoelectron Spectroscopy ◽

Annealing Temperature ◽

Radio Frequency Magnetron ◽

Radio Frequency Magnetron Sputtering ◽

X Ray Diffraction ◽

Free Electrons ◽

X Ray ◽

Mg Content

Zirconium-doped MgxZn1−xO (Zr-doped MZO) mixed-oxide films were investigated, and the temperature sensitivity of their electric and optical properties was characterized. Zr-doped MZO films were deposited through radio-frequency magnetron sputtering using a 4-inch ZnO/MgO/ZrO2 (75/20/5 wt%) target. Hall measurement, X-ray diffraction (XRD), transmittance, and X-ray photoelectron spectroscopy (XPS) data were obtained. The lowest sheet resistance, highest mobility, and highest concentration were 1.30 × 103 Ω/sq, 4.46 cm2/Vs, and 7.28 × 1019 cm−3, respectively. The XRD spectra of the as-grown and annealed Zr-doped MZO films contained MgxZn1−xO(002) and ZrO2(200) coupled with Mg(OH)2(101) at 34.49°, 34.88°, and 38.017°, respectively. The intensity of the XRD peak near 34.88° decreased with temperature because the films that segregated Zr4+ from ZrO2(200) increased. The absorption edges of the films were at approximately 348 nm under 80% transmittance because of the Mg content. XPS revealed that the amount of Zr4+ increased with the annealing temperature. Zr is a potentially promising double donor, providing up to two extra free electrons per ion when used in place of Zn2+.

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Effect of washing procedures on trace-element content of hair.

Clinical Chemistry ◽

10.1093/clinchem/23.9.1771 ◽

1977 ◽

Vol 23 (9) ◽

pp. 1771-1772 ◽

Cited By ~ 51

Author(s):

G S Assarian ◽

D Oberleas

Keyword(s):

Trace Element ◽

Trace Element Analysis ◽

Trace Element Content ◽

Magnesium Content ◽

Preparation Technique ◽

Element Analysis ◽

Significant Difference ◽

Trace Element Status ◽

Mg Content ◽

Source Of Information

Abstract A pooled sample of hair was divided and portions prepared for analysis by three washing procedures, to evaluate the effect of washing procedure on the subsequent trace-element (Zn, Cu, Mg) content. The methods selected were a detergent wash, a hexane-ethanol wash, and an acetone-ether-detergent wash. For all elements, there was a significant difference among the results after these wash procedures. Magnesium content of hair was most affected by washing, containing less than half of the magnesium of the unwashed hair. The detergent wash removed the most zinc and magnesium; the acetone-ether-detergent wash removed the most copper. Our results indicate that the trace-element analysis of hair is sensitive to the preparation technique and therefore is an unreliable source of information about trace-element status.

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Influence of Mg on Resistivity, Adhesion, Agglomeration of Ag(Mg)/SiO2/Si Multilayers

MRS Proceedings ◽

10.1557/proc-686-a9.9 ◽

2001 ◽

Vol 686 ◽

Author(s):

Bongjoo Kang ◽

Heejung Yang ◽

Sungjin Hong ◽

Yeonkyu Ko ◽

Chang-Oh Jeong ◽

...

Keyword(s):

High Temperature ◽

Annealing Temperature ◽

Enhanced Resistance ◽

Free Silicon ◽

Mg Content ◽

Mgo Layers

AbstractThe effect of Mg in Ag(Mg)/SiO2/Si multilayers on adhesion, agglomeration, and resistivity after annealing in vacuum at 200 to 500 have been investigated. The annealing of Ag(Mg)/SiO2/Si multilayers produced surface and interfacial MgO layers, resulting in MgO/Ag(Mg)/MgO/SiO2/Si structure. The presence of surface MgO provided the passivation against air, thus leading to the significantly enhanced resistance to agglomeration. In addition, the resistivity of Ag(Mg) film decreased by lowering Mg content and increasing the annealing temperature as well. Furthermore, Ag adhesion to SiO2 was improved due to the formation of the interfacial MgO layer resulting from the reaction of segregated Mg with SiO2. Also, the negligible solubility of Si in Ag prevented the dissolution of free silicon produced from the reaction, Mg + SiO2 = MgO + Si, which was in contrast with the dissolution of a significant amount of silicon released from the SiO2 substrate in Cu(Mg)/SiO2/Si multilayers after annealing at high temperature, e.g., 400. The dissolved Si in Cu caused the rapid increase in resistivity in Cu(Mg)/SiO2/Si.

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