2026-04-22T20:18:28Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/55942024-07-25T07:18:53Zcom_10259_9476com_10259.4_106com_10259_2604col_10259_9477

High-entropy transition metal diborides by reactive and non-reactive spark plasma sintering: A comparative investigation Tallarita, Giovanna Licheri, Roberta Garroni, Sebastiano Barbarossa, Simone Orrù, Roberto Cao, Giacomo High-entropy ceramics Borides Spark plasma sintering Self-propagating high-temperature synthesis Resistance to oxidation The direct synthesis and consolidation by SPS (1950 °C, 20 min, 20 MPa) of high-entropy (Hf0.2Mo0.2Zr0.2Nb0.2Ti0.2)B2 from elemental powders resulted in a multiphase product. An increase of the heating rate determined a change of the mechanism governing the synthesis reaction from gradual solid-state diffusion to rapid combustion regime, while the final conversion degree was 67 wt.%. The sintered product displayed a non-uniform microstructure with the presence of 10–15 μm sized pores, due to volatilization phenomena occurring during the combustion synthesis reaction. In contrast, when the SPS process was preceded by powder synthesis via SHS, a homogeneous single-phase ceramic was obtained. Clear benefits are derived by the use of SHS, able to provide very shortly powders with elemental species very well intermixed, so that the obtainment of (Hf0.2Mo0.2Zr0.2Nb0.2Ti0.2)B2 during the subsequent SPS stage is strongly promoted. The resulting 92.5% dense product shows superior oxidation resistance with respect to individual borides prepared with the same method. 2021-01-13T11:25:12Z 2021-01-13T11:25:12Z 2021-01-13T11:25:12Z 2020-04 info:eu-repo/semantics/article 0955-2219 http://hdl.handle.net/10259/5594 10.1016/j.jeurceramsoc.2019.10.031 eng Journal of the European Ceramic Society. 2020, V. 40, n. 4, p. 942-952 https://doi.org/10.1016/j.jeurceramsoc.2019.10.031 http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess Attribution-NonCommercial-NoDerivatives 4.0 Internacional Elsevier