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[en] The geometrical structures and electronic properties of six fullerene isomers of C₁₀₀ were studied at the HF/6-31G^* and B3LYP/6-31G* levels, respectively. The results of the fully optimized calculations show that three C₁₀₀ isomers 449:D₂, 425:C₁ and 442:C₂ are near isoenergetic isomers. The energies and properties of C₁₀₀ hexaanions were calculated. The C₁₀₀^6- (450:D₅) isomer is predicted to be the most stable isomer at the B3LYP/6-31G* level, and the C₁₀₀^6- (449:D₂) isomer is 44.1 kcal/mol higher in energy. The heterofullerenes C₉₆X₄ (X=N, P, B, Si) formed from the initial C₁₀₀ (449:D₂) have also been investigated at the B3LYP/6-31G* level. The HOMO-LUMO gaps and aromaticities show that the replacement of fullerene carbon atoms with four heteroatoms can enhance the electronic stabilization of C₁₀₀ (449:D₂).

[en] The present report summarizes and discusses the recent results on developing a modern, nuclear grade FeCrAl alloy designed to have enhanced radiation tolerance and weldability. The alloys used for these investigations are modern FeCrAl alloys based on a Fe-13Cr-5Al-2Mo-0.2Si-0.05Y alloy (in wt.%, designated C35M). Development efforts have focused on assessing the influence of chemistry and microstructure on the fabricability and performance of these newly developed alloys. Specific focus was made to assess the weldability, thermal stability, and radiation tolerance.

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[en] The aging alloy of AIMgSil containing Mg₂Si of 1.29 % has been done with the following steps: e.q (a) part of the specimen was heated at 400^oC during 3 hours, and (b) the other part was done with solution treatment at 550^oC followed by quenching. After quenching a part of the specimen was aged at room temperature and other specimen was aged at 160^oC during 16 hours. After the specimen had been heated, then it was shaped into thin foil to be examined by Transmission Electron Microscope. The result showed that the heating at temperature of 400^oC during 3 hours created a second phase (i.e.Mg₂Si) was like stick shape with the hexagonal structure at [0111] orientation and matrix [001], and the hardness was 31 HB. The aging of specimen at room temperature gave result a GP zone which was like the needles shape in the dislocation area of the face center cubic structure at [111] orientation and [111] matrix. The hardness obtained was 64 HB. In the other hand the aging process at temperature of 160^oC within 16 hours have resulted the precipitate which was greater than that of the former needle shaped as the face center cubic structure without dislocation at matrix with [111] orientation and [114] matrix. The hardness at this condition was 94 HB

[en] The amorphous alloys of the Fe_81.4-Cr_4.0-Mo_6.0-Ni_5.2C_1.0-Mn_2.1-Al_0.3, Fe_71.7-Ni_6.0-Co_2.4-Cr_7.5-Mo_7.9-B_4.0Si_0.5, Fe₈₆-P_9.8C_1.0-Si_0.9-Al_1.7-B_0.6 systems obtained through the method of the melt fast quenching on the copper disk external side, are studied. The thickness of bands was varied in the limits of 50-80 μm. The cooling rate of bands was constituted 8 x 10⁵ deg C/s. The plastic deformation of the obtained alloys was accomplished through the procedure of the local deformation of amorphous alloy surface by the Vickers diamond pyramid. Thereafter the indenter deformation picture was investigated by the optical and electron microscopes. The anisotropy of the iron base amorphous alloys plastic deformation was revealed. This event is explained on the basis of the notions on the internal strains in the isotropic amorphous bands

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[en] We have used Moessbauer spectroscopy to study the influence of Si addition to Fe₆₀Al₄₀ composition without changing the iron content of the alloy. The study has been performed in ordered and mechanically deformed samples. This work shows that the B2 structure present in ordered Fe₆₀Al₄₀ alloy does not change with Si introduction in the studied ternary alloys. However, the binary Fe₆₀Si₄₀ alloy shows D03 and B20 structures. Mechanical deformation of the ordered samples induces a clear change of the Moessbauer spectra of binary alloys with the presence of new sextets or variation of the previous ones; however, the Moessbauer spectra of the studied ternary alloys are very similar to the ordered ones.

[en] The Si addition has a great impact on the glass forming ability of Cu${}_{50}$Zr${}_{43}$Al${}_7$ bulk metallic glass (BMG). To investigate the effective role of Si doping on the crystallization behavior of the BMGs, crystallization transformation kinetics of Cu${}_{50}$Zr${}_{43}$Al${}_7$ and (Cu${}_{50}$Zr${}_{43}$Al${}_7$)${}_{99}$Si${}_1$ BMGs were explored at non-isothermal and isothermal conditions by differential scanning calorimetry (DSC) experiments. The Si doping enhances the activation energy of crystallization transformation (resistance against crystallization) under both thermal circumstances. Avrami exponents were obtained by employing the Johnson–Mehl–Avrami–Kolmogorov (JMAK) model. In the isothermal regime, Avrami exponents in both BMGs were 2.2, which reveals that the dominant mechanism of crystallization is the three-dimensional growth with a decreasing nucleation rate of crystals. The time-temperature-transformation or TTT diagram displayed that minor alloying of Si displaced the crystallization transformation to elevated temperatures and longer incubation times.