22831-39-6Relevant articles and documents
Alternative route for the preparation of CoSb3 and Mg 2Si derivatives
Godlewska,Mars,Zawadzka
, p. 109 - 113 (2012)
An alternative manufacturing route has been developed for cobalt triantimonide and magnesium disilicide derivatives. Elemental powders were mixed in stoichiometric proportions, cold pressed into cylindrical preforms and heated in oxygen-free environment to initiate the exothermic reaction. According to DTA/TG measurements and observations under high-temperature microscope, the onset of reaction occurred at a temperature not exceeding the melting point of the more volatile component, i.e. antimony in the case of CoSb3 and magnesium in the case of Mg2Si. The reaction products were additionally heat treated to secure homogenization. Dense sinters were obtained by hot uniaxial pressing of the obtained powders in moderate temperature-and-pressure conditions. Several advantages were identified in the proposed technology: absence of liquid phases, relatively short time of the synthesis, possibility of in-situ or ex-situ doping and grain size control.
Thermoelectric Properties and Transport Mechanism of Pure and Bi-Doped SiNWs-Mg2Si
Yang, Xiaomeng,Chen, Shaoping,Zhang, Hua,Lv, Feng,Fan, Wenhao,Wang, Wenxian,Munir, Zuhair A.
, (2018)
Through the use of nano-Si wires as additive, a significant improvement in the thermoelectric (TE) properties of Mg2Si is achieved. SiNWs-Mg2Si materials are prepared by a wet etching method followed by field activated pressure assisted synthesis (FAPAS). The results show that the presence of SiNWs successfully decouples the relationship between the electrical resistivity and the Seebeck coefficient of Mg2Si. The effect of doping with Bi is also investigated. The results show that the addition of Bi changed the scattering mechanism, and a zT value of 0.47 is determined at 800 K for Mg2Si0.99Bi0.01-0.005SiNWs. The presence of MgO as an impurity and its effect on zT are discussed.
Electrochemical characteristics of intermetallic phases in aluminum alloys : An experimental survey and discussion
Birbilis,Buchheit
, p. B140-B151 (2005)
This paper presents a survey of corrosion potentials, pitting potentials, and electrochemical characteristics for intermetallic particles commonly present in high-strength aluminum-based alloys. Results from relevant pure metals and solid solutions are also presented. It is seen that corrosion potentials and pitting potentials vary over a wide range for various intermetallics. Elaboration of the results reveals that the electrochemical behavior of intermetallics is more detailed than the simple noble or active classification based upon corrosion potential or estimated from the intermetallic composition. Intermetallics capable of sustaining the largest cathodic current densities are not necessarily those with the most noble Ecorr, similarly those with the least noble Ecorr will not necessarily sustain the largest anodic currents. The data herein was collected via the use of a microcapillary electrochemical cell facilitating electrode investigations upon intermetallic particles in the micrometer-squared range. This survey may be used as a tool for clarification of localized corrosion phenomena in Al alloys.
Nanoporous silicon prepared through air-oxidation demagnesiation of Mg2Si and properties of its lithium ion batteries
Liang, Jianwen,Li, Xiaona,Hou, Zhiguo,Guo, Cong,Zhu, Yongchun,Qian, Yitai
, p. 7230 - 7233 (2015)
Nanoporous silicon has been prepared through the air-oxidation demagnesiation of Mg2Si at 600 °C for 10 hours (Mg2Si + O2 → Si + MgO), followed by HCl washing. Mg2Si was prepared from 200 mesh commercial Si at 500 °C for 5 h in an autoclave. The as-prepared Si exhibits a reversible capacity of 1000 mA h g-1 at 36 A g-1 and ～1200 mA h g-1 at 1.8 A g-1 over 400 cycles. This journal is
A metathesis reaction route to obtain fine Mg2Si particles
Itahara,Yamada,Oh,Asahi,Imagawa,Yamane
, p. 4315 - 4318 (2014)
We have developed a novel synthetic route for the production of fine Mg2Si particles (2, and Na. Mg2Si was suggested to be formed by a solid-state metathesis reaction, in which MgCl2 reacts with Na to form Mg and NaCl, and then Mg reacts with NaSi.
Structural, electronic, and hydriding properties of Li2MgSi
Herbst,Meyer
, p. 65 - 68 (2010)
An investigation of Li2MgSi, with particular emphasis on its potential as a hydrogen storage material, is reported. A cubic P over(4, ?) 3 m crystal structure, differing from previous determinations, is established. We find that the material reversibly sorbs ～2.8 mass% hydrogen at T ～ 300 °C according to the reaction Li2MgSi + H2 ? 1/2Mg2Si + 2LiH + 1/2Si. Electronic structure calculations indicate that Li2MgSi is a semiconductor with a small, indirect gap of ～0.2 eV.
Mill setting and microstructural evolution during mechanical alloying of Mg2Si
Riffel,Schilz
, p. 3427 - 3431 (1998)
The mechanical alloying behaviour of magnesium and silicon to form the intermetallic compound Mg2Si and the optimum setting of a planetary ball mill for this task, were examined. For the ductile-brittle magnesium-silicon system it was found that the efficiency of the mill is mostly influenced by the ratio of the angular velocity of the planetary wheel to that of the system wheel and the amount of load. The examination of the kinetics inside the planetary ball mill for different mill settings showed that a ratio of angular velocities of at least 3 is necessary to compensate the reduction of efficiency due to slip. The optimum powder load for the 500 ml vial was found to be 10-20 g. The milling process starts with elemental magnesium and silicon bulk particles. During the milling, the silicon pieces are rapidly diminished and together with the constantly forming Mg2Si they act as an emery powder for the magnesium bulk pieces. Simultaneous to the diminution of the magnesium, alloying occurs.
Thermoelectric properties of Bi-doped Mg2Si semiconductors
Tani, Jun-Ichi,Kido, Hiroyasu
, p. 218 - 224 (2005)
The thermoelectric properties of Bi-doped Mg2Si (Mg 2Si:Bi=1:x) fabricated by spark plasma sintering process have been characterized by Hall effect measurements at 300 K and by measurements of electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) between 300 and 900 K. Bi-doped Mg2Si samples are n-type in the measured temperature range. The electron concentration of Bi-doped Mg2Si at 300 K ranges from 1.8×1019 cm -3 for the Bi concentration x=0.001 to 1.1×1020 cm-3 for x=0.02. The solubility limit of Bi in Mg2Si is estimated to be about 1.3 at% and first-principles calculation revealed that Bi atoms are expected to be primarily located at the Si sites in Mg2Si. The electrical resistivity, Seebeck coefficient, and thermal conductivity are strongly affected by the Bi concentration. The sample of x=0.02 shows a maximum value of the figure of merit, ZT, is 0.86 at 862 K.
Combined effect of high-intensity ultrasonic treatment and Ca addition on modification of primary Mg2Si and wear resistance in hypereutectic Mg-Si alloys
Moussa,Waly,El-Sheikh
, p. 576 - 581 (2014)
The combined effect of high-intensity ultrasonic treatment (HIUST) and 0.3 wt.%Ca addition on modification of primary Mg2Si and wear resistance in the hypereutectic Mg-5 wt.%Si alloy has been investigated. The results show that without treatmen
Synthesis of a low-density Ti-Mg-Si alloy
Senkov,Cavusoglu,Froes
, p. 246 - 252 (2000)
A low-density titanium alloy was synthesized from blended elemental powders of TiH2, Mg, and Si by mechanical alloying and/or heat treatment. The titanium hydride was used in place of titanium. Phase transformations occurring in the system during heating at a constant rate were studied with the use of DTA and XRD. During heating of the blended elemental powders decomposition of titanium hydride occurred in the temperature range 550-750 °C and some silicon went into solid solution in titanium while the majority of the silicon reacted exothermically with magnesium at about 500 °C producing an intermetallic phase Mg2Si. This phase was stable on heating up to 950 °C, where a eutectic component of this phase began to melt leading to formation of a liquid solution of magnesium in silicon, followed by a reaction of the liquid silicon with titanium and formation of a Ti5Si3 phase. A third reaction in the system was detected at about 1100 °C due to formation of MgO, so that after annealing at 1150 °C three stable phases, Ti(Si), Ti5Si3, and MgO, were present in the alloy. No decomposition of the Ti5Si3 phase or formation of Mg2Si were detected either during subsequent cooling or a second heating of the alloy. Completely different kinetics of the phase reactions occurred in the mechanically alloyed powders. Magnesium and silicon dissolved in the titanium hydride during mechanical alloying. Decomposition of the titanium hydride occurred at 320-600 °C, the Mg2Si phase was formed after heating to 450 °C, and the Ti5Si3 phase was detected after heating to 570 °C. The Mg2Si decomposed completely at a temperature of 650 °C with the formation of MgO and Ti5Si3. After heating to 1150 °C, three stable phases, TiN0.3, Ti5Si3, and MgO, were present in the alloy. A discussion of the results is given.
