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Nanometric hetero‐interfaces provide a wealth of scientific and engineering opportunities due to their complex and often misunderstood properties that can differ from their respective bulk constituents. In this work, the ability for engineered nanostructures within a bulk U─Mo alloy to arrest simulant fission products is investigated experimentally and computationally. Nanostructured 90 wt% U/ 10 wt% Mo (U‐10Mo) with 7.1 at% Nd is consolidated using spark‐plasma‐ sintering (SPS) techniques and is heat‐treated at 500 °C under vacuum for 24, 100, 500, and 1000 h. Analysis on the sintered and heat‐treated U‐10Mo reveals rapid kinetics in Nd diffusion to nanocluster sites, with evidence of Nd diffusion occurring during sintering and during the following heat‐treatment. The segregation behavior of Nd at two different U─Mo/UN interfaces is computationally verified using density functional theory (DFT) to reinforce experimental data. This work endeavors to engineer uranium mononitride (UN) nanostructures within a metallic nuclear fuel (U─Mo), in order to trap potential fission products (Nd). From consolidation of the nanostructured U─Mo powders all the way to 1000 h at reactor‐like temperatures (500 °C), Nd preferentially migrates to nanostructure boundaries (hetero‐interfaces). This technology can help prevent fuel‐cladding chemical interactions while not reducing fuel smear density within nuclear reactor cores.

Oxide-dispersion-strengthened (ODS) steel is considered as a promising candidate structural material for nuclear applications. In this study, the microstructure and mechanical properties of Y4Zr3O12-added Fe–13.5Cr–2W ODS steels, containing high contents of C and N, prepared by mechanical alloying (MA) and two-step spark plasma sintering (SPS), were investigated. The results showed that pure Y4Zr3O12 powders, with a grain size of 3.5 nm, were well prepared with NH3·H2O addition by the sol-gel method in advance, in order to avoid the formation of some coarse or undesired oxides. W was completely dissolved into the matrix after 48 h of ball milling at 300 rpm, and the main elements were uniformly distributed on the surface of the milled powders. The unexpected face-centered cubic (FCC, γ)/body-centered cubic (BCC, α) dual-phase structure of the sintered specimens, could be explained by the unexpectedly high contents of C and N from the raw powder production process, fast-sintering characteristic of SPS, and inhibitory effect of W on the diffusion of C. The experimental results were approximately consistent with the simulation results from the Thermo Calc software. The temperature combination of 800 °C and 1100 °C during the SPS process, provided a relatively more homogeneous microstructure, while the combination of 750 °C and 1150 °C, provided the highest ultimate tensile strength (UTS), of 1038 MPa, with the highest uniform elongation (UE), of 6.2%. M23C6, Cr2O3, M2(C,N), and other precipitates, were mainly distributed at grain boundaries, especially at the triple junctions, which led to Cr depletion at grain boundaries.

This paper investigates and analyses use of numerical modeling by finite element method (FEM) at studying of consolidation processes of materials from powder by spark plasma sintering (SPS). Tasks of SPS process optimization is discussed in detail. Examples of numeric analysis of SPS of current conducting and non-conducting materials are given. Numeric modeling of sample sintering with hybrid method when SPS process is combined with hot pressing (HP) process is studied. Also paper presents development prospects of principles of SPS process numeric modeling.

In this study, Fe-40wt% TiB2 nanocomposite powders were fabricated by two different methods: (1) conventional powder metallurgical process by simple high-energy ball-milling of Fe and TiB2 elemental powders (ex-situ method) and (2) high-energy ball-milling of the powder mixture of (FeB+TiH2) followed by reaction synthesis at high temperature (in-situ method). The ex-situ powder was prepared by planetary ball-milling at 700 rpm for 2 h under an Ar-gas atmosphere. The in-situ powder was prepared under the same milling condition and heat-treated at 900oC for 2 h under flowing argon gas in a tube furnace to form TiB2 particulates through a reaction between FeB and Ti. Both Fe-TiB2 composite powder compacts were sintered by a spark-plasma sintering (SPS) process. Sintering was performed at 1150℃ for the ex-situ powder compact and at 1080℃ for the in-situ powder for 10 minutes under 50 MPa of sintering pressure and 0.1 Pa vacuum for both processes. The heating rate was 50o/min to reach the sintering temperature. Results from analysis of shrinkage and microstructural observation showed that the in-situ composite powder compacts had a homogeneous and fine microstructure compared to the ex-situ preparation, even though the sintered densities were almost the same (99.6 and 99.8% relative density, respectively).

Multi-component solid solutions with non-stoichiometric compositions are characteristics of ultra-high temperature carbides as promising materials for hypersonic vehicles. However, for group IV transition-metal carbides, the oxidation behavior of multi-component non-stoichiometric (Zr,Hf,Ti)C x carbide solid solution has not been clarified yet. The present work fabricated four kinds of (Zr,Hf,Ti)C x carbide solid solution powders by free-pressureless spark plasma sintering to investigate the oxidation behavior of (Zr,Hf,Ti)C x in air. The effects of metallic atom composition on oxidation resistance were examined. The results indicate that the oxidation kinetics of (Zr,Hf,Ti)C x are composition dependent. A high Hf content in (Zr,Hf,Ti)C x was beneficial to form an amorphous Zr-Hf-Ti-C-O oxycarbide layer as an oxygen barrier to enhance the initial oxidation resistance. Meanwhile, an equiatomic ratio of metallic atoms reduced the growth rate of (Zr,Hf,Ti)O 2 oxide, increasing its phase stability at high temperatures, which improved the oxidation activation energy of (Zr, Hf, Ti)C x .

The paper describes the method for producing WC-10wt%Co hard alloy with 99.6% of the theoretical density and a Vickers hardness of ~1400 HV 0.5. Experimental data on densification dynamics, phase composition, morphology, mechanical properties, and grain size distribution of WC-10%wtCo using spark plasma sintering (SPS) within the range of 1000–1200 °C are presented. The high quality of the product is provided by the advanced method of high-speed powder mixture SPS-consolidation at achieving a high degree of densification with minimal calculated grain growth at 1200 °C.

This paper presents the possibilities of using the reaction sintering method for the production of tool steel used in medicine. The applied method enables the sintering of powders in one technological process. The SPS (spark plasma sintering) process is a technology in which electric pulses generate heat and pressure, which allows for the quick and effective connection of powder particles into a homogeneous material with high density and good mechanical properties. As a result, a product of small dimensions and a precisely defined chemical composition, established at the stage of preparing the powder mixture, is obtained. The advantages of the applied production process are the sintering time and small amounts of post-production waste compared to conventional methods of producing a finished product from steel. The method of producing a semi-finished product is particularly useful in the case of small-scale and small-sized production. The subject of the research was the analysis of the conditions for obtaining X30Cr13 martensitic steel used for the production of surgical instruments. This paper analyzes the effect of sintering temperature and time on sinterability and on selected physical and mechanical properties of the obtained materials. The sintering parameters of the starting mixture have been optimized to obtain the highest possible sinter properties, such as density and hardness. Based on the analysis of the results, it was found that the powder preparation method for the SPS process and the grain size significantly affect the microstructure and mechanical properties of the final product. The optimal sintering parameters for X30Cr13 steel are a temperature of 950 °C and a sintering time of 12 min. Furthermore, the use of the SPS method allows for a reduction in the manufacturing costs of martensitic steel semi-finished products.

AA7075 aluminum alloy is widely used for several high-technology applications for its high mechanical strength to weight ratio but is still the subject of several studies seeking a further increase in its mechanical properties. A commercial powder is used, either as-received or after ball-milling. Dense AA7075 samples are prepared in one step by Spark Plasma Sintering, at 550 °C with a holding time of 15 min and a uniaxial pressure of 100 MPa. No additional heat treatment is performed. Laser granulometry, X-ray diffraction and optical- and scanning electron microscopy show that both grain size and morphology are preserved in the dense samples, due to the relatively low temperature and short sintering time used. The samples prepared using the ball-milled powder exhibit both higher Vickers microhardness and transverse fracture strength values than those prepared using the raw powder, reflecting the finer microstructure.

Gradual evolution of bulk equimolar (Nb, Ti, Zr, Cr)B 2 was studied via boro-carbothermal reduction of metal oxides with varying B 4 C content (0.45 mol–0.75 mol) at 1800 °C for 75 min, adopting single-stage reactive spark plasma sintering scheme. The phase evolution and microstructural investigation revealed almost fully formed high-entropy boride (HEB) phase for B 4 C content of 0.7 mol with a small amount of retained phases; graphite, Cr 2 O 3, and intermittent Nb 0.8 Zr 0.2 C. The HEB phase in the sintered specimens exhibits hardness up to 37 GPa with elastic modulus up to 415 GPa, depending on the B 4 C content in the pre-mix. The sintered specimen's thermal conductivity increases with temperature, attaining 28 W/m K at 1600 °C. Thermodynamic and diffusion calculations reveal that the boro-carbothermal reaction between oxides yields individual metal borides, which are then interdiffused to form the HEB phase. The unique methodology is expected to serve as a promising route for obtaining multicomponent diborides. Graphical abstract Reaction and diffusion controlled pathway can yield multicomponent diborides in an in-situ reactive-spark plasma sintering process.

To achieve high oxygen blocking structure of the ZrB 2 -MoSi 2 coating applied on carbon structural material, ZrB 2 -MoSi 2 coating was prepared by spark plasma sintering (SPS) method utilizing ZrB 2 -MoSi 2 composite powders synthesized by self-propagating high-temperature synthesis (SHS) technique as raw materials. The oxygen blocking mechanism of the ZrB 2 -MoSi 2 coatings at 1973 K was investigated. Compared with commercial powders, the coatings prepared by SHS powders exhibited superior density and inferior oxidation activity, which significantly heightened the structural oxygen blocking ability of the coatings in the active oxidation stage, thus characterizing higher oxidation protection efficiency. The rise of MoSi 2 content facilitated the dispersion of transition metal oxide nanocrystals (5–20 nm) in the SiO 2 glass layer and conduced to the increasing viscosity, thus strengthening the inerting impact of the compound glass layer in the inert oxidation stage. Nevertheless, the ZrB 2 -40 vol%MoSi 2 coating sample prepared by SHS powders presented the lowest oxygen permeability of 0.3% and carbon loss rate of 0.29×10 −6 g·cm −2 ·s −1 . Owing to the gradient oxygen partial pressure inside the coatings, the Si-depleted layer was developed under the compound glass layer, which brought about acute oxygen erosion.