A theoretical and experimental investigation on the SHS synthesis of (HfTiCN)-TiB2 high-entropy composite

Evseev, Nikolay; Matveev, Alexey; Nikitin, Pavel; Abzaev, Yu. A.; Жуков, И. А.

doi:10.1016/j.ceramint.2022.02.144

Cited by 7 publications

(4 citation statements)

References 36 publications

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“…The phase composition was refined using the Rietveld method. In this work, the CASTEP program code [ 14 , 15 ] was used to calculate the energies of the reference and refined crystal lattices within the framework of the density functional theory (DFT) using the generalized-gradient approximation (GGA). The microstructure of the Al 12 Mg 17 -B powder and sintered specimens (as well as the mean diameter) was determined using a JEOL JSM-6490 microscope with energy dispersive spectroscopy (EDS).…”

Section: Methodsmentioning

confidence: 99%

Phase Composition, Structure and Properties of the Spark Plasma Sintered Ceramics Obtained from the Al12Mg17-B-Si Powder Mixtures

Nikitin¹,

Zhukov²,

Matveev³

et al. 2022

Nanomaterials

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In this work, composite materials were obtained by spark plasma sintering of an Al12Mg17-B-Si powder mixture. The structure, phase composition, and mechanical properties of the obtained composites were studied. It was found that various compounds based on B12 icosahedrons, such as AlB12, B4Si, and B6Si, are formed during spark plasma sintering. Based on the SEM images and results of XRD analysis of the obtained specimens, a probable scheme for the formation of the phase composition of composite materials during spark plasma sintering was proposed. An increase in the Al12Mg17-B powder content in the initial mixture from 30 to 70 wt% leads to an increase in hardness from 16.55 to 21.24 GPa and a decrease in the friction coefficient and wear rate from 0.56 to 0.32 and 13.60 to 5.60 10−5 mm−3/(N/m), respectively.

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Section: Methodsmentioning

confidence: 99%

Phase Composition, Structure and Properties of the Spark Plasma Sintered Ceramics Obtained from the Al12Mg17-B-Si Powder Mixtures

Nikitin¹,

Zhukov²,

Matveev³

et al. 2022

Nanomaterials

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“…The theoretical XRD pattern was obtained by combining three reference XRD patterns of AlMgB 14 , TiB 2 and Al 4 B 2 O 9 phases. The CASTEP program code [ 12 , 13 ] was used to calculate the free energies (E) of the reference and refined crystal lattices within the framework of the density functional theory (DFT) using the generalized-gradient approximation (GGA). Ultrasoft pseudopotentials were used, and the cutoff energy was 500 eV.…”

Section: Methodsmentioning

confidence: 99%

Experimental and Theoretical Study of Ultra-Hard AlMgB14-TiB2 Composites: Structure, Hardness and Self-Lubricity

et al. 2022

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It is known that the presence of oxygen phases in hard materials leads to an undesirable decrease in the mechanical properties. In materials based on AlMgB14, the main oxygen impurity is spinel MgAl2O4; it significantly reduces the hardness of AlMgB14 and its formation during sintering is inevitable. In this work, the ultra-hard spark plasma sintered (SPSed) AlMgB14-TiB2 composite material was fabricated from the AlMgB14-TiB2 precursor obtained by self-propagating high-temperature synthesis (SHS). Due to the high synthesis temperatures, the main oxygen phase in the obtained composite was Al4B2O9 instead of spinel MgAl2O4. It was found that the obtained composite has excellent mechanical properties. The maximum hardness of the sample is 44.1 GPa. The presence of oxygen in the form of the Al4B2O9 phase led to unexpected results: the friction coefficient of the obtained AlMgB14-TiB2 composite under dry conditions against the Al2O3 counter-specimen is approximately four times lower than the friction coefficient of pure ceramic AlMgB14 (0.18 against 0.7, respectively). Based on the observed results, it was found that the Al4B2O9 particles formed during the SHS are responsible for the low friction coefficient. The quantum chemical calculations showed that the elastic moduli of Al4B2O9 are significantly smaller than the elastic moduli of AlMgB14 and TiB2. Thus, during sliding, Al4B2O9 particles are squeezed out onto the composite surface, form the lubricating layer and reduce the friction coefficient.

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“…The structure was formed in the course of in situ synthesis supported by exothermic reactions between the initial mixture components. It should be noted that the SH synthesis process is supported by the heat produced by these reactions, thus making it possible to obtain powder materials without external energy input [ 14 , 15 , 16 , 17 ]. One of the main disadvantages of the SHS method is high porosity of synthesized materials [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

Structure, Properties and Phase Composition of Composite Materials Based on the System NiTi-TiB2

et al. 2022

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This article considers issues pertinent to the research of the phase composition, structure and mechanical properties of materials obtained from powders of composite (Ni-Ti)-TiB2, which have prospective applications in aerospace and automotive industry and engine construction. The starting powder materials (Ni-Ti)-TiB2 were obtained by self-propagating high-temperature synthesis (SHS). Research samples were produced using high-temperature vacuum sintering. It was shown that the use of such materials increases the wettability of the particles and allows the production of composites, the density of which is 95% of the theoretical one. Average particle size was 1.54 µm, average microhardness was 8 GPa, which is an order of magnitude higher than the average microhardness of pure nickel-based and titanium-based alloys, and the ultimate strength values were comparable to those of tungsten-based heavy alloys.

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A theoretical and experimental investigation on the SHS synthesis of (HfTiCN)-TiB2 high-entropy composite

Cited by 7 publications

References 36 publications

Phase Composition, Structure and Properties of the Spark Plasma Sintered Ceramics Obtained from the Al12Mg17-B-Si Powder Mixtures

Phase Composition, Structure and Properties of the Spark Plasma Sintered Ceramics Obtained from the Al12Mg17-B-Si Powder Mixtures

Experimental and Theoretical Study of Ultra-Hard AlMgB14-TiB2 Composites: Structure, Hardness and Self-Lubricity

Structure, Properties and Phase Composition of Composite Materials Based on the System NiTi-TiB2

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