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1

Effect of Fabrication Method of Fe-TiB2 Nanocomposite Powders on Spark-Plasma Sintering Behavior

Bae Sun-Woo, Huynh Xuan-Khoa, Kim Ji-Soon

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 3

1023--1028

EN

In this study, Fe-40wt% TiB2 nanocomposite powders were fabricated by two different methods: (1) conventional powder metallurgical process by simple high-energy ball-milling of Fe and TiB2 elemental powders (ex-situ method) and (2) high-energy ball-milling of the powder mixture of (FeB+TiH2 ) followed by reaction synthesis at high temperature (in-situ method). The ex-situ powder was prepared by planetary ball-milling at 700 rpm for 2 h under an Ar-gas atmosphere. The in-situ powder was prepared under the same milling condition and heat-treated at 900°C for 2 h under flowing argon gas in a tube furnace to form TiB2 particulates through a reaction between FeB and Ti. Both Fe-TiB2 composite powder compacts were sintered by a spark-plasma sintering (SPS) process. Sintering was performed at 1150°C for the ex-situ powder compact and at 1080°C for the in-situ powder for 10 minutes under 50 MPa of sintering pressure and 0.1 Pa vacuum for both processes. The heating rate was 50°/min to reach the sintering temperature. Results from analysis of shrinkage and microstructural observation showed that the in-situ composite powder compacts had a homogeneous and fine microstructure compared to the ex-situ preparation, even though the sintered densities were almost the same (99.6 and 99.8% relative density, respectively).

2

On Adsorption of Hydrogen on (100) Titanium Hydride Surface

Gryciuk M., Górecki J.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 10

1981-1990

EN

We apply quantum density functional theory methods to calculate the reaction path linking a free hydrogen molecule placed over TiH2 (100) surface with a pair of hyrogen atoms ad sorbed on it. The considered path is composed of highly symmetrical orientations of H2 molecule; in the process of dissociative adsorption the line linking hydrogen atoms is al ways parallel to the surface and located on the symmetry plane of the supercell. The results indicate that adsorption is characterized by the energetic barrier (1.18 eV/molecule) and the reaction heat (0.26 eV/ atom).

3

On hydrogen Layers on the (100)Titanium Hydride Surface

Gryciuk M., Górecki J.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 7

993-999

EN

Electronic structure calculations based on the density functional theory (DFT) have been applied to the adsorption of hydrogen on the (100) plane of TiH2. Calculations have been performed for a supercell of TiH2 and the periodic boundary conditions have been used. Three different monolayers, two double layers and one selected submonolayer of hydrogen have been considered. It is shown that the most dense coverage corresponds to a submonolayer composed of atoms in the bridge position with respect to titanium atoms on the surface. Both, binding energy and the hydrogen density on the surface agree with the experimental results.