Chemical Composition and Structure of Interfacial Boundaries in Cr3C2–Ti Powder Hard Alloys after Explosive Compaction and Subsequent Heatingстатья
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Дата последнего поиска статьи во внешних источниках: 1 апреля 2022 г.
Авторы:
Krokhalev A.V. ,
Kharlamov V.O. ,
Kuzmin S.V. ,
Lysak V.I.
Журнал:
Russian Journal of Non-Ferrous Metals
Том:
61
Номер:
6
Год издания:
2020
Первая страница:
667
Последняя страница:
674
DOI:
10.3103/S1067821220060139
Аннотация:
The results of studying the fine structure, chemical composition, and phase composition of boundaries between components of the Cr3C2–Ti hard alloy containing 40 wt % titanium binder in the state after the explosion compaction, as well as after heat treatment, are presented. The heating temperature of the powder mixture during the shock-wave loading is 730°C and the pressure is 14 GPa, which provides the maximal compaction and consolidation of the powder mixture without sintering. Compact samples are heat-treated at a temperature from 400 to 700°C with holding in the furnace for 1 h with subsequent cooling in calm air. The equilibrium phase composition is calculated by numerical thermodynamic modeling using the Thermo-Calc software complex. The structure and elemental composition are investigated using FEI Quanta 3D and Versa 3D electron microscopes with an integrated system of the focused ion beam for foil preparation, as well as FEI Techai G2 20F and Titan 80-300 transmission electron microscopes with the mode of transmission foil scanning. A Bruker D8 Advance diffractometer is used to perform X-ray phase analysis. It is shown that the formation of strong interphase boundaries during the explosion compaction of mixtures of titanium carbide and chromium carbide powders is accompanied by chemical interaction between components with the formation of near-boundary layers having a total thickness on the order of 90 nm. The continuous monotonic variation in Cr and Ti contents is observed in the limits of the transient layer with an almost invariable carbon concentration. The phase composition of the layers corresponds to the equilibrium one calculated under the shockwave compression pressure of 12 GPa, but it is thermodynamically nonequilibrium under standard conditions. Heating to 400°C leads to the dissolution of near-boundary layers and transition of Cr3C2–Ti hard alloys into the two-phase state. Alternating layers consisting of carbon-depleted chromium carbides (Cr7C3, Cr23C6) and titanium carbide (TiC), formed due to the carbon diffusion from the initial chromium carbide (Cr3C2) to titanium, are formed along interfacial boundaries at a temperature of 700°C. © 2020, Allerton Press, Inc.
Добавил в систему:
Кузьмин Сергей Викторович