This paper deals with the effect of microstructure condition on ignition temperature, mechanical and corrosion properties of commercial WE43 alloy prepared by various processing techniques including conventional casting, extrusion, and powder metallurgy methods such as spark plasma sintering. For different processing technique, differences in microstructures were observed, including different grain sizes, intermetallic phases, amount of alloying elements in the solid solutions, or specific structural elements. Mechanical and corrosion properties were improved especially by grain refinement. Precipitation from oversaturated solid solutions led to further improvement of mechanical properties, while corrosion resistance was just slightly decreased due to the fine and homogeneously distributed precipitates of Mg41Nd5. The obtained results indicate huge differences in ignition resistance based on the metallurgical state of the microstructure. An improved ignition resistance was obtained at the condition with a higher concentration of proper alloying elements (Y, Nd, Gd, Dy) in the solid solution and absence of eutectic phases in the microstructure. Thermally stable intermetallic phases had a minor effect on resulting ignition temperature.
3 April 2025 in Journal of Physics D: Applied Physics
This study evaluates the erosion resistance and thermal stability of Cu/W–La2O3 composite electrodes exposed to plasma arc conditions in ambient air. Through comparative analysis with pure copper and W–La2O3 electrodes, it was found that the Cu/W–La2O3 composites exhibit superior erosion resistance, with a notably advantageous negative erosion rate due to a self-formed oxide layer that mitigates surface degradation. Detailed microstructural characterization revealed that this oxide layer, primarily consisting of copper tungstates and lanthanum tungstates, enhances electrode durability by reducing oxidation rates and improving heat dissipation. This adaptive surface layer also contributes to a more stable arc, effectively minimizing material loss, particularly at higher current intensities where pure copper electrodes experience rapid thermal and oxidative degradation. The findings suggest that Cu/W–La2O3 composites, with their negative erosion rates, offer significant benefits for air plasma torches, making them promising candidates for applications demanding high-performance and long-lasting electrodes in oxidizing environments.
9 August 2023 in Journal of Engineering Materials and Technology
Powder metallurgy products display superior performance compared to traditionally cast ingots. The final properties of these products can be altered through various methods, such as pre-treatment of the powder. This study focuses on different pre-treatment techniques, including milling, chemical treatment, and heat treatment, as well as their combinations. The results show that distinct microstructures were produced, and their impact on mechanical and corrosion properties was evaluated. The results indicate that milling and chemical treatment increase the yield strength of the material by up to 34 MPa but decrease the elongation by up to 5%. On the other hand, heat treatment increases the elongation by up to 7% but decreases the yield strength by up to 36 MPa. Corrosion resistance is improved especially by chemical and heat treatment of powders, where the corrosion rate was observed to decrease by up to 50% in comparison to the value of product from atomized powder. Additionally, all types of powder pre-treatment were found to improve the corrosion resistance of the final product. This provides an opportunity to tailor the mechanical and corrosion properties of these materials to meet specific applications.
The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered (LPSO) phases that improves strength and ductility with minimal amounts of alloying elements. Even better improvements are associated with the specific microstructure known as the Mille-Feuille structure (MFS) that can occur in this alloy as well after proper heat treatment. This study systematically compares the traditional ingot metallurgy method with the Bridgman method (slow cooling), coupled with diverse heat treatments and extrusion process. Microscopic analyses reveal variations in the presence of LPSO phases, Mille-Feuille structure, and especially grain size, leading to divergent mechanical and corrosion properties. The Bridgman approach surprisingly stands out, ensuring superior mechanical properties due to kink and texture strengthening.
Zinc oxide (ZnO) nanostructures suffer from fast electron–hole recombination, limiting their applicability in photocatalytic environmental remediation, and carbon additives such as detonation nanodiamonds (DNDs) are constrained by their high defect density. To address this, ZnO nanocomposites modified with high-pressure, high-temperature nanodiamonds (HPHT NDs) were synthesized to evaluate whether their intrinsically lower defect density—evidenced by a dominant diamond Raman peak at 1330 cm−1 and a low sp2 carbon fraction of 6.6% compared to oxidized DNDs with strong D/G bands (~1350/1580 cm−1) and ~25–35% sp2 carbon—can enhance charge separation and improve photocatalytic activity. Oxidized HPHT NDs bearing carbonyl, carboxyl, and hydroxyl groups enabled covalent attachment to ZnO, and the resulting ND–ZnO composites were characterized by SEM/EDX, ATR-FTIR, Raman spectroscopy, XPS, and cathodoluminescence (CL). EDX confirmed increasing carbon incorporation from 13.0 to 52.9 at.%, while XPS revealed a 0.5 eV shift in the Zn 2p3/2 peak and an increase in Zn–O–Zn lattice oxygen from 31.3% to 61.6% in ND–ZnO 10. CL showed enhanced near-band-edge emission and reduced Zni-related luminescence (~3.0 eV). ND–ZnO 10 achieved a nearly threefold-higher degradation rate constant (0.0251 min−1) than pristine ZnO (0.0087 min−1) and retained 88% efficiency after five cycles, demonstrating strong potential for durable wastewater treatment.