In situ ZA27/TiB₂ composites were synthesized successfully by diluting the in situ Al/TiB₂ composite, which was used as a master alloy. The microstructure and hardness of the developed in situ composites have been investigated. Results have shown that TiB₂ particles distribute uniformly through the matrix and significantly refine the matrix grain. The hardness of the composites was higher than that of the matrix alloy and increased with the increasing TiB₂ content. The dry sliding wear behavior under heavy loads and high rotation speed were studied in detail by using a pin-on-disc wear tester at room temperature. The results revealed that the wear resistance of the composites increased monotonically with the increase in the TiB₂ content. The composites had a lower coefficient of friction, friction temperature, wear rate, and specific wear rate especially under high loads when compared with the matrix alloy. An increase in the applied load increased the wear severity by changing the wear mechanism from abrasion and oxidation to adhesive wear. The composites possess better adhesive wear resistance properties compared with the matrix, which shows obvious adhesive wear as the load increased to 36 N, while the ZA27/3.0% TiB₂ composite did not show adhesive wear until the load increased to 54 N.

Refractory high-entropy or medium-entropy alloys (RHEAs, RMEAs) exhibit outstanding strength and hold significant promise for high-temperature applications. However, their pronounced brittleness at room temperature restricts their industrial application. Recently, the introduction of interstitial oxygen has proven effective in refining the microstructure and improving the mechanical properties of RMEAs. In this study, we investigated the effect of interstitial oxygen content ranging from 0.5 to 6 at.% on the microstructures and mechanical properties of TiZrNb MEA. The alloys display a single BCC structure, showing a dendritic crystal morphology. At an oxygen content of 4 at.%, the alloy shows a room-temperature compressive yield strength of 1300 MPa and compressive strain of over 50%, achieving a balanced strength and ductility combination. Moreover, it shows excellent high-temperature mechanical properties, with yield strength exceeding 500 MPa at 800 °C. The Toda-Caraballo and Labusch theoretical models were used in the study to clarify the strengthening mechanism of the alloys, and the theoretical yield strengths obtained by calculation coincided with the experimental yield strengths. This validation not only confirms that the primary strengthening mechanism is solid solution strengthening, but also proves the reliability of the model in predicting the mechanical properties of MEAs and provides a theoretical basis for the use of interstitial atoms to strengthen MEAs.

It is still highly desired to develop efficient, resource-abundant and inexpensive electrocatalysts to improve the sluggish kinetics of oxygen evolution reaction (OER) in electrochemical water splitting systems. In this work, the large-area ultrathin (2.52 nm thick) Ce-doped La ₂ O ₃ nanofilms were developed via a facile and reliable ionic layer epitaxy method with different Ce content. The ultrathin Ce-doped La ₂ O ₃ nanofilm with optimum composition of La _1.22 Ce _0.78 O ₃ exhibited an excellent OER performance with a very low overpotential of 221 mV at 10 mA cm ⁻² and a small Tafel slope of 33.7 mV dec ⁻¹ . A remarkable high mass activity of 6263.2 A g ⁻¹ was also obtained from ultrathin La _1.22 Ce _0.78 O ₃ nanofilm at the overpotential of 221 mV. Such a high mass activity was three orders of magnitude higher than state-of-the-art commercial IrO ₂ powders (3.8 A g ⁻¹ ) and more than 30 times higher than La ₂ O ₃ nanofilm (196.7 A g ⁻¹ ) without Ce doping at the same overpotential. This high mass activity was even significantly higher than other recently reported typical OER catalysts. The substantial OER performance gain by the Ce doping was attributed to the improved conductivity and electrochemical active surface areas of nanofilms as a result of favorable tuning on the charge transfer and electronic structures. This work provides a promising approach to develop high-performance two-dimensional (2D) electrocatalysts by effective heteroatom doping strategy.

In this paper, as-annealed FeCoNiCrMn plates were laser-welded with preplaced FeCoNiCrMn and FeCoNiCrAl powders, respectively. The grains in the fusion zone of the weld with FeCoNiCrMn powder have a reduced aspect ratio compared to those without preplaced powders and the weld with FeCoNiCrAl powder presents relative equiaxed grains. The yield strength of each weld has been remarkably enhanced when referring to the base alloy, and the ultimate tensile strength of each weld with preplaced powder exceeds 80% of that of the base and the maximum reaches 88.5% when referring to the weld with preplaced FeCoNiCrMn powder. Cleavage fractography was observed in the welds. The finding of this work will service the engineering practices of high-entropy alloys.