arXiv subjects

Jozef Vleugels

Publications and source records attributed to Jozef Vleugels.

3 recordsLinked to original sources

arXiv2020

Deposition of MAX phase containing thin films from a (Ti,Zr)2AlC compound target

This work reports on sputter depositions carried out from a compound (Ti,Zr)2AlC target, whereupon Al-containing (Ti,Zr)C thin films (30-40 nm in thickness) were deposited on MgO(111) and Al2O3(0001) substrates at temperatures ranging between 500 and 900 °C. The presence of Al within the carbide structure was evidenced by lattice parameter variations. Furthermore, chemical analyses showed that the Al distribution throughout the film thickness was fairly homogeneous. Thicker films (80-90 nm) deposited from the same compound target consisted of the pseudo-binary (Ti,Zr)C and intermetallic compounds in the Ti-Zr-Al system up to 800 °C, as well as solid solution MAX phases with different Ti:Zr ratios at 900 °C. X-ray diffraction and transmission electron microscopy showed that both (Ti,Zr)2AlC and (Ti,Zr)3AlC2 solid solution MAX phases were formed. Moreover, this work discusses the growth mechanism of the thicker films, which started with the formation of the mixed (Ti,Zr)C carbide, followed by the nucleation and growth of aluminides, eventually leading to the formation of the MAX phases, which was the primary objective of the sputter depositions.

cond-mat.mtrl-sci↗

arXiv2020

Compatibility of $Zr_{2}AlC$ MAX phase-based ceramics with oxygen-poor, static liquid lead-bismuth eutectic

This work investigates the compatibility of $Zr_{2}AlC$ MAX phase-based ceramics with liquid LBE, and proposes a mechanism to explain the observed local $Zr_{2}AlC$/LBE interaction. The ceramics were exposed to oxygen-poor ($C_{O}\le2.2 \cdot10^{-10}$ mass%), static liquid LBE at 500°C for 1000 h. A new $Zr_{2}(Al,Bi,Pb)C$ MAX phase solid solution formed in-situ in the LBE-affected $Zr_{2}AlC$ grains. Out-of-plane ordering was favorable in the new solid solution, whereby $\textit{A}$-layers with high and low-Bi/Pb contents alternated in the crystal structure, in agreement with first-principles calculations. Bulk $Zr_{2}(Al,Bi,Pb)C$ was synthesized by reactive hot pressing to study the crystal structure of the solid solution by neutron diffraction.

cond-mat.mtrl-sci↗

arXiv2019

Synthesis, properties and thermal decomposition of the Ta4AlC3 MAX phase

The present work describes a synthesis route for bulk Ta4AlC3 MAX phase ceramics with high phase purity. Pressure assisted densification was achieved by both hot pressing and spark plasma sintering of tantalum hydride, aluminium and carbon powder mixtures in the 1200-1650°C range. The phases present and microstructures were characterized as a function of the sintering temperature by X-ray diffraction and scanning electron microscopy. High-purity alfa-Ta4AlC3 was obtained by hot pressing at 1500°C for 30 min at 30 MPa. The beta-Ta4AlC3 allotrope was observed in the samples produced by SPS. The elastic modulus, Vickers hardness, flexural strength and single-edge V-notch beam fracture toughness of the high-purity bulk sample were determined. The thermal decomposition of Ta4AlC3 into tantalum carbide and Al vapor in high vacuum at 1200°C and 1250°C was also investigated, as a possible processing route to produce porous tantalum carbide components.

cond-mat.mtrl-sci↗