Changes in the phase microstructure and composition of the Cr3C2 – Ti system of powdered solid alloys made though explosive compaction were considered at temperatures from 300 to 1200 °C in an ...oxidizing atmosphere. Measurements were taken with scanning transmission electron microscopy (FEI Versa 3d), energy dispersive X-ray (EDAX Apollo-X), and thermographic analysis (NETZSCH STA 449 F3 Jupiter). The results show the temperature ranges at which the chemical reactions between carbide and metal phases with atmospheric oxygen and with each other occur.
The results of studying the fine structure, chemical composition, and phase composition of boundaries between components of the Cr
3
C
2
–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 Cr
3
C
2
–Ti hard alloys into the two-phase state. Alternating layers consisting of carbon-depleted chromium carbides (Cr
7
C
3
, Cr
23
C
6
) and titanium carbide (TiC), formed due to the carbon diffusion from the initial chromium carbide (Cr
3
C
2
) to titanium, are formed along interfacial boundaries at a temperature of 700°C.
An overview of the results of an experimental study of the effect of the type and content of the metal binder, the parameters of shock-wave compression and subsequent heating on the formation of hard ...alloys and coatings from them during the explosive treatment of CrC-Ti powder mixtures on steel substrates is presented, the mechanism of wear and antifriction properties of the obtained materials is described.
The kinetics of the processes of primary hydrogenation of material based on TiFe obtained by explosive pressing of titanium and iron powders with subsequent heat treatment has been investigated. ...Using the results obtained and mathematical processing of the curves using the Avraami-Erofeev equation, it was revealed that the mechanism of their saturation with hydrogen corresponds to the classical concepts of reaction diffusion. The process begins with the formation of a layer of solid solutions of hydrogen on the surface of the material in the initial phases of the material and after the latent period continues with the formation of a layer of hydride phases. t is shown that the hydrogen storage material TiFe + TiFe has a significantly higher hydrogen capacity than single-phase TiFe.
The paper presents the results of studies of diffusion processes in a five-layer explosion-welded composite titanium VT-20+steel 08Cr18Ni10Ti after heat treatment at temperatures of 850 and 900 ° C ...and holding times of 20-100 hours. The features of the formation of the microstructure, microhardness, and the chemical composition of the diffusion zones of the composite have been studied using optical and electron microscopy and X-ray spectral analysis.
The results of optical and electron microscopic metallographic studies and energy-dispersive analysis of the structure and composition in the zone of connection of copper M3 with steel 30 CrMnSiA ...after explosion welding, subsequent quenching from a temperature of 880 ° C and high tempering at a temperature of 520 ° C are presented. The change in the distribution of hardness and chemical elements over the cross section of the bimetal, the formation of martensite in melts after quenching and its decomposition during high tempering are shown.
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