ПОСЛІДОВНІ ТВЕРДОФАЗНІ ПЕРЕТВОРЕННЯ hBN(1)-cBN-hBN(2) ПРИ 7 ГПa В УМОВАХ ЕКСТPЕМАЛЬНО ВИСОКИХ ТЕМПЕРАТУРНИХ ГРАДІЄНТІВ
New technical solution for high-pressure cell (HPC) design was developed appling to toroidal type apparatus (HPA-T30). The cell assembly allows creating a significant radially directed gradient (ÑT) of around ~250 °C/mm in the reaction volume of the apparatus. From the point of view of HPHT experime...
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| Date: | 2024 |
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| Main Authors: | , , , , , |
| Format: | Article |
| Language: | English |
| Published: |
Институт сверхтвердых материалов им. В. Н. Бакуля Национальной академии наук Украины
2024
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| Subjects: | |
| Online Access: | http://altis-ism.org.ua/index.php/ALTIS/article/view/365 |
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| Journal Title: | Tooling materials science |
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Tooling materials science| Summary: | New technical solution for high-pressure cell (HPC) design was developed appling to toroidal type apparatus (HPA-T30). The cell assembly allows creating a significant radially directed gradient (ÑT) of around ~250 °C/mm in the reaction volume of the apparatus. From the point of view of HPHT experiment methodology this approach gives an opportunity to record structural changes and solid-phase transformations of compounds depending on temperature within the only one sample volume. The capabilities of the method were demonstrated by the example of the thermobaric behavior of graphite-like boron nitride (hBN) at a pressure of 7 GPa in a wide temperature range reaching the level of~ 3000 °C. The evolution of solid-phase transformations of primary hBN(1) followed the sequence hBN(1)-cBN-hBN(2), i.e., included the stage of reconversion of cubic cBN into secondary hBN(2) at temperatures above 2680°C. The structural features of the final phase indicated the formation of a polycrystalline structure of hBN(2) at the stages of recrystallization annealing (grain growth process) under high-temperature thermobaric triatment. |
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