TY  - JOUR
AU  - Corlett, Cole A.
AU  - Obradović, Nina
AU  - Watts, Jeremy L.
AU  - Bohannan, Eric W.
AU  - Fahrenholtz, William G.
PY  - 2023
UR  - https://dais.sanu.ac.rs/123456789/14708
AB  - The synthesis, densification behavior, and crystallographic site occupancy were investigated for four different spinel-based ceramics, including a high-entropy spinel (Co0.2Cu0.2Mg0.2Ni0.2 Zn0.2)Al2O4. Each composition was reacted to form a single phase, but analysis of X-ray diffraction patterns revealed differences in cation site occupancy with the high-entropy spinel being nearly fully normal. Densification behavior was investigated and showed that fully dense ceramics could be produced by hot pressing at temperatures as low as 1375°C for all compositions. Vickers’ hardness values were at least 10 GPa for all compositions. The cations present in the high-entropy spinel appear to have a stabilizing effect that led to nearly normal site occupancy compared to full cation inversion behavior of nickel aluminate spinel. This is the first report that compares cation site occupancy of a high-entropy spinel to conventional spinel ceramics.
PB  - Informa UK Limited
T2  - Journal of Asian Ceramic Societies
T1  - Synthesis, densification, and cation inversion in high entropy (Co,Cu,Mg,Ni,Zn)Al2O4 spinel
SP  - 1
SP  - 330
EP  - 8
EP  - 337
VL  - 11
IS  - 3
DO  - 10.1080/21870764.2023.2227535
UR  - https://hdl.handle.net/21.15107/rcub_dais_14708
ER  - 

@article{
author = "Corlett, Cole A. and Obradović, Nina and Watts, Jeremy L. and Bohannan, Eric W. and Fahrenholtz, William G.",
year = "2023",
abstract = "The synthesis, densification behavior, and crystallographic site occupancy were investigated for four different spinel-based ceramics, including a high-entropy spinel (Co0.2Cu0.2Mg0.2Ni0.2 Zn0.2)Al2O4. Each composition was reacted to form a single phase, but analysis of X-ray diffraction patterns revealed differences in cation site occupancy with the high-entropy spinel being nearly fully normal. Densification behavior was investigated and showed that fully dense ceramics could be produced by hot pressing at temperatures as low as 1375°C for all compositions. Vickers’ hardness values were at least 10 GPa for all compositions. The cations present in the high-entropy spinel appear to have a stabilizing effect that led to nearly normal site occupancy compared to full cation inversion behavior of nickel aluminate spinel. This is the first report that compares cation site occupancy of a high-entropy spinel to conventional spinel ceramics.",
publisher = "Informa UK Limited",
journal = "Journal of Asian Ceramic Societies",
title = "Synthesis, densification, and cation inversion in high entropy (Co,Cu,Mg,Ni,Zn)Al2O4 spinel",
pages = "1-330-8-337",
volume = "11",
number = "3",
doi = "10.1080/21870764.2023.2227535",
url = "https://hdl.handle.net/21.15107/rcub_dais_14708"
}

Corlett, C. A., Obradović, N., Watts, J. L., Bohannan, E. W.,& Fahrenholtz, W. G.. (2023). Synthesis, densification, and cation inversion in high entropy (Co,Cu,Mg,Ni,Zn)Al2O4 spinel. in Journal of Asian Ceramic Societies
Informa UK Limited., 11(3), 1-8.
https://doi.org/10.1080/21870764.2023.2227535
https://hdl.handle.net/21.15107/rcub_dais_14708

Corlett CA, Obradović N, Watts JL, Bohannan EW, Fahrenholtz WG. Synthesis, densification, and cation inversion in high entropy (Co,Cu,Mg,Ni,Zn)Al2O4 spinel. in Journal of Asian Ceramic Societies. 2023;11(3):1-8.
doi:10.1080/21870764.2023.2227535
https://hdl.handle.net/21.15107/rcub_dais_14708 .

Corlett, Cole A., Obradović, Nina, Watts, Jeremy L., Bohannan, Eric W., Fahrenholtz, William G., "Synthesis, densification, and cation inversion in high entropy (Co,Cu,Mg,Ni,Zn)Al2O4 spinel" in Journal of Asian Ceramic Societies, 11, no. 3 (2023):1-8,
https://doi.org/10.1080/21870764.2023.2227535 .,
https://hdl.handle.net/21.15107/rcub_dais_14708 .

TY  - CONF
AU  - Kosanović, Darko
AU  - Fahrenholtz, William G.
AU  - Obradović, Nina
AU  - Filipović, Suzana
AU  - Watts, Jeremy L.
AU  - Hilmas, G. E.
PY  - 2023
UR  - https://dais.sanu.ac.rs/123456789/15009
AB  - The thermal properties of zirconium diboride (ZrB2) ceramics with tungsten additions of up to 5 wt% were characterized up to 2000°C. Densification was promoted by the addition of 0.5 wt% carbon. ZrB2 ceramics were prepared from commercially available powder by hot pressing. The crystalline phases present were determined by x-ray diffraction. The microstructure and density change as a result of the addition of tungsten, but this does not affect much the thermal behavior of ZrB2 at room and elevated temperatures. Thermal diffusivity at 200°C decreased from 0.158 cm2/s for nominally pure ZrB2 to 0.149 cm2/s for ZrB2 with 5 wt% Tungsten carbide (WC). The thermal diffusivity decreased with increasing temperature, reaching a value of 0.145 cm2/s at 2000°C for ZrB2 with 5 wt% Tungsten carbide (WC). Heat capacity, unlike thermal diffusivity, did not change during thermal cycling. Thermal conductivity, which was calculated from thermal diffusivity, heat capacity, and density, was as high as 77.9 W/(m·K) at 2000°C for ZrB2 with 5 wt% Tungsten carbide (WC). Any level of Tungsten carbide (WC) contamination reduces thermal conductivity. Properties, including hardness, oxygen content, elastic modulus, strength were measured and will be discussed.
PB  - Belgrade : University of Belgrade - Faculty of Mechanical Engineering
C3  - Programme and The Book of Abstracts / International Conference of Experimental and Numerical Investigations and New Technologies - CNN TECH 2023, 04 – 07 July 2023, Zlatibor, Serbia
T1  - Elevated Temperature Thermal Properties of ZrB2 with Tungsten Additions
SP  - 79
UR  - https://hdl.handle.net/21.15107/rcub_dais_15009
ER  - 

@conference{
author = "Kosanović, Darko and Fahrenholtz, William G. and Obradović, Nina and Filipović, Suzana and Watts, Jeremy L. and Hilmas, G. E.",
year = "2023",
abstract = "The thermal properties of zirconium diboride (ZrB2) ceramics with tungsten additions of up to 5 wt% were characterized up to 2000°C. Densification was promoted by the addition of 0.5 wt% carbon. ZrB2 ceramics were prepared from commercially available powder by hot pressing. The crystalline phases present were determined by x-ray diffraction. The microstructure and density change as a result of the addition of tungsten, but this does not affect much the thermal behavior of ZrB2 at room and elevated temperatures. Thermal diffusivity at 200°C decreased from 0.158 cm2/s for nominally pure ZrB2 to 0.149 cm2/s for ZrB2 with 5 wt% Tungsten carbide (WC). The thermal diffusivity decreased with increasing temperature, reaching a value of 0.145 cm2/s at 2000°C for ZrB2 with 5 wt% Tungsten carbide (WC). Heat capacity, unlike thermal diffusivity, did not change during thermal cycling. Thermal conductivity, which was calculated from thermal diffusivity, heat capacity, and density, was as high as 77.9 W/(m·K) at 2000°C for ZrB2 with 5 wt% Tungsten carbide (WC). Any level of Tungsten carbide (WC) contamination reduces thermal conductivity. Properties, including hardness, oxygen content, elastic modulus, strength were measured and will be discussed.",
publisher = "Belgrade : University of Belgrade - Faculty of Mechanical Engineering",
journal = "Programme and The Book of Abstracts / International Conference of Experimental and Numerical Investigations and New Technologies - CNN TECH 2023, 04 – 07 July 2023, Zlatibor, Serbia",
title = "Elevated Temperature Thermal Properties of ZrB2 with Tungsten Additions",
pages = "79",
url = "https://hdl.handle.net/21.15107/rcub_dais_15009"
}

Kosanović, D., Fahrenholtz, W. G., Obradović, N., Filipović, S., Watts, J. L.,& Hilmas, G. E.. (2023). Elevated Temperature Thermal Properties of ZrB2 with Tungsten Additions. in Programme and The Book of Abstracts / International Conference of Experimental and Numerical Investigations and New Technologies - CNN TECH 2023, 04 – 07 July 2023, Zlatibor, Serbia
Belgrade : University of Belgrade - Faculty of Mechanical Engineering., 79.
https://hdl.handle.net/21.15107/rcub_dais_15009

Kosanović D, Fahrenholtz WG, Obradović N, Filipović S, Watts JL, Hilmas GE. Elevated Temperature Thermal Properties of ZrB2 with Tungsten Additions. in Programme and The Book of Abstracts / International Conference of Experimental and Numerical Investigations and New Technologies - CNN TECH 2023, 04 – 07 July 2023, Zlatibor, Serbia. 2023;:79.
https://hdl.handle.net/21.15107/rcub_dais_15009 .

Kosanović, Darko, Fahrenholtz, William G., Obradović, Nina, Filipović, Suzana, Watts, Jeremy L., Hilmas, G. E., "Elevated Temperature Thermal Properties of ZrB2 with Tungsten Additions" in Programme and The Book of Abstracts / International Conference of Experimental and Numerical Investigations and New Technologies - CNN TECH 2023, 04 – 07 July 2023, Zlatibor, Serbia (2023):79,
https://hdl.handle.net/21.15107/rcub_dais_15009 .

TY  - CONF
AU  - Silvestroni, Laura
AU  - Gilli, Nicola
AU  - Obradović, Nina
AU  - Filipović, Suzana
AU  - Watts, Jeremy L.
AU  - Fahrenholtz, William G.
PY  - 2022
UR  - https://dais.sanu.ac.rs/123456789/13617
AB  - ZrB2 is widely recognized as the most prominent ultra-high temperature ceramic for aerospace applications, in view of its melting point above 3000°C, and despite it exhibits lower oxidation and ablation resistance as compared to HfB2, it has a much lower density. The addition of TiB2 further lowers the overall weight, which is a relevant factor for materials intended to flight, but it also worsen the oxidation resistance. In this work, different Mecompounds, where Me = Nb, Hf, Cr, V, are added to the ZrB2-TiB2 system to study their effect on the densification, microstructure and thermo-mechanical properties. By adjusting the processing and sintering cycles, fully dense multi-phase ceramics with density in the 5.3-5.7 g/cm3 range and hardness close to 24 GPa have been obtained. A common feature to all materials, is the formation of solid solutions and microstructural details obtained by x-ray diffraction, scanning and electron microscopy are highlighted. Particularly, we explored the nanotexturing of the shell within micron-sized boride grains of the matrix, which resulted from the preferential precipitation of Me-compounds with poor solubility within ZrB2 or TiB2 lattice. Preliminary bending strength and oxidation behavior of these intricate bulk multiphase ceramics are also provided.
PB  - Belgrade : Serbian Ceramic Society
C3  - Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application X New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 26-27. September 2022.
T1  - Multi-phase (Zr,Ti,Me)B2 solid solutions: preparation and microstructure evolution
SP  - 37
EP  - 37
UR  - https://hdl.handle.net/21.15107/rcub_dais_13617
ER  - 

@conference{
author = "Silvestroni, Laura and Gilli, Nicola and Obradović, Nina and Filipović, Suzana and Watts, Jeremy L. and Fahrenholtz, William G.",
year = "2022",
abstract = "ZrB2 is widely recognized as the most prominent ultra-high temperature ceramic for aerospace applications, in view of its melting point above 3000°C, and despite it exhibits lower oxidation and ablation resistance as compared to HfB2, it has a much lower density. The addition of TiB2 further lowers the overall weight, which is a relevant factor for materials intended to flight, but it also worsen the oxidation resistance. In this work, different Mecompounds, where Me = Nb, Hf, Cr, V, are added to the ZrB2-TiB2 system to study their effect on the densification, microstructure and thermo-mechanical properties. By adjusting the processing and sintering cycles, fully dense multi-phase ceramics with density in the 5.3-5.7 g/cm3 range and hardness close to 24 GPa have been obtained. A common feature to all materials, is the formation of solid solutions and microstructural details obtained by x-ray diffraction, scanning and electron microscopy are highlighted. Particularly, we explored the nanotexturing of the shell within micron-sized boride grains of the matrix, which resulted from the preferential precipitation of Me-compounds with poor solubility within ZrB2 or TiB2 lattice. Preliminary bending strength and oxidation behavior of these intricate bulk multiphase ceramics are also provided.",
publisher = "Belgrade : Serbian Ceramic Society",
journal = "Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application X New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 26-27. September 2022.",
title = "Multi-phase (Zr,Ti,Me)B2 solid solutions: preparation and microstructure evolution",
pages = "37-37",
url = "https://hdl.handle.net/21.15107/rcub_dais_13617"
}

Silvestroni, L., Gilli, N., Obradović, N., Filipović, S., Watts, J. L.,& Fahrenholtz, W. G.. (2022). Multi-phase (Zr,Ti,Me)B2 solid solutions: preparation and microstructure evolution. in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application X New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 26-27. September 2022.
Belgrade : Serbian Ceramic Society., 37-37.
https://hdl.handle.net/21.15107/rcub_dais_13617

Silvestroni L, Gilli N, Obradović N, Filipović S, Watts JL, Fahrenholtz WG. Multi-phase (Zr,Ti,Me)B2 solid solutions: preparation and microstructure evolution. in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application X New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 26-27. September 2022.. 2022;:37-37.
https://hdl.handle.net/21.15107/rcub_dais_13617 .

Silvestroni, Laura, Gilli, Nicola, Obradović, Nina, Filipović, Suzana, Watts, Jeremy L., Fahrenholtz, William G., "Multi-phase (Zr,Ti,Me)B2 solid solutions: preparation and microstructure evolution" in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application X New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 26-27. September 2022. (2022):37-37,
https://hdl.handle.net/21.15107/rcub_dais_13617 .

TY  - JOUR
AU  - Corlett, Cole A.
AU  - Frontzek, Matthias D.
AU  - Obradović, Nina
AU  - Watts, Jeremy L.
AU  - Fahrenholtz, William G.
PY  - 2022
UR  - https://dais.sanu.ac.rs/123456789/13516
AB  - The synthesis and crystallographic site occupancy were investigated for MgAl2O4 with and without mechanical activation of the precursor powders. Heating to 1200 °C or higher resulted in the formation of a single spinel phase regardless of whether the powders were mechanically activated or not. Neutron diffraction analysis was used to determine cation site occupancy and revealed that mechanical activation resulted in a lower degree of cation site inversion compared to the nonactivated materials, which indicated that the powders were closer to thermodynamic equilibrium. This is the first study to characterize the effects of mechanical activation on crystallographic site occupancy in magnesium aluminate spinel using neutron diffraction. © 2022 by the authors.
T2  - Materials
T1  - Mechanical Activation and Cation Site Disorder in MgAl2O4
VL  - 15
IS  - 18
DO  - 10.3390/ma15186422
UR  - https://hdl.handle.net/21.15107/rcub_dais_13516
ER  - 

@article{
author = "Corlett, Cole A. and Frontzek, Matthias D. and Obradović, Nina and Watts, Jeremy L. and Fahrenholtz, William G.",
year = "2022",
abstract = "The synthesis and crystallographic site occupancy were investigated for MgAl2O4 with and without mechanical activation of the precursor powders. Heating to 1200 °C or higher resulted in the formation of a single spinel phase regardless of whether the powders were mechanically activated or not. Neutron diffraction analysis was used to determine cation site occupancy and revealed that mechanical activation resulted in a lower degree of cation site inversion compared to the nonactivated materials, which indicated that the powders were closer to thermodynamic equilibrium. This is the first study to characterize the effects of mechanical activation on crystallographic site occupancy in magnesium aluminate spinel using neutron diffraction. © 2022 by the authors.",
journal = "Materials",
title = "Mechanical Activation and Cation Site Disorder in MgAl2O4",
volume = "15",
number = "18",
doi = "10.3390/ma15186422",
url = "https://hdl.handle.net/21.15107/rcub_dais_13516"
}

Corlett, C. A., Frontzek, M. D., Obradović, N., Watts, J. L.,& Fahrenholtz, W. G.. (2022). Mechanical Activation and Cation Site Disorder in MgAl2O4. in Materials, 15(18).
https://doi.org/10.3390/ma15186422
https://hdl.handle.net/21.15107/rcub_dais_13516

Corlett CA, Frontzek MD, Obradović N, Watts JL, Fahrenholtz WG. Mechanical Activation and Cation Site Disorder in MgAl2O4. in Materials. 2022;15(18).
doi:10.3390/ma15186422
https://hdl.handle.net/21.15107/rcub_dais_13516 .

Corlett, Cole A., Frontzek, Matthias D., Obradović, Nina, Watts, Jeremy L., Fahrenholtz, William G., "Mechanical Activation and Cation Site Disorder in MgAl2O4" in Materials, 15, no. 18 (2022),
https://doi.org/10.3390/ma15186422 .,
https://hdl.handle.net/21.15107/rcub_dais_13516 .