Synergistic Effects of Boron and Rare Earth Elements on the Microstructure and Stress Rupture Properties in a Ni-Based Superalloy.

The synergistic effects of boron (B) and rare earth (RE) elements on the microstructure and stress rupture properties were investigated in a Ni-based superalloy. The stress rupture lifetime at 650 °C/873 MPa significantly increased with the addition of B as a single element. Furthermore, the stress rupture lifetime reached its peak (303 h), with a certain amount of B and RE added together in test alloys. Although the grain size and morphology of the γ' phase varied a little with the change in B and RE addition, they were not considered to be the main reasons for stress rupture performance. The enhancement in stress rupture lifetime was mostly attributed to the segregation of the B and RE elements, which increased the binding force of the grain boundary and improved its strength and plasticity. In addition, the enrichment of B and RE inhabited the precipitation of carbides along grain boundaries. Furthermore, nano-scale RE precipitates containing sulfur (S) and phosphorus (P) were observed to be distributed along the grain boundaries. The purification of grain boundaries by B and RE elements was favorable to further improve the stress rupture properties.

Novel Insight into Rechargeable Aluminum Batteries with Promising Selenium Sulfide@Carbon Nanofibers Cathode.

Due to the unique electronic structure of aluminum ions (Al3+ ) with strong Coulombic interaction and complex bonding situation (simultaneously covalent/ionic bonds), traditional electrodes, mismatching with the bonding orbital of Al3+ , usually exhibit slow kinetic process with inferior rechargeable aluminum batteries (RABs) performance. Herein, to break the confinement of the interaction mismatch between Al3+ and the electrode, a previously unexplored Se2.9 S5.1 -based cathode with sufficient valence electronic energy overlap with Al3+ and easily accessible structure is potentially developed. Through this new strategy, Se2.9 S5.1 encapsulated in multichannel carbon nanofibers with free-standing structure exhibits a high capacity of 606 mAh g-1 at 50 mA g-1 , high rate-capacity (211 mAh g-1 at 2.0 A g-1 ), robust stability (187 mAh g-1 at 0.5 A g-1 after 3,000 cycles), and enhanced flexibility. Simultaneously, in/ex-situ characterizations also reveal the unexplored mechanism of Sex Sy in RABs.

Facile Synthesis of FePS3 Nanosheets@MXene Composite as a High-Performance Anode Material for Sodium Storage.

Searching for advanced anode materials with excellent electrochemical properties in sodium-ion battery is essential and imperative for next-generation energy storage system to solve the energy shortage problem. In this work, two-dimensional (2D) ultrathin FePS3 nanosheets, a typical ternary metal phosphosulfide, are first prepared by ultrasonic exfoliation. The novel 2D/2D heterojunction of FePS3 nanosheets@MXene composite is then successfully synthesized by in situ mixing ultrathin MXene nanosheets with FePS3 nanosheets. The resultant FePS3 nanosheets@MXene hybrids can increase the electronic conductivity and specific surface area, assuring excellent surface and interfacial charge transfer abilities. Furthermore, the unique heterojunction endows FePS3 nanosheets@MXene composite to promote the diffusion of Na+ and alleviate the drastic change in volume in the cyclic process, enhancing the sodium storage capability. Consequently, the few-layered FePS3 nanosheets uniformly coated by ultrathin MXene provide an exceptional reversible capacity of 676.1 mAh g-1 at the current of 100 mA g-1 after 90 cycles, which is equivalent to around 90.6% of the second-cycle capacity (746.4 mAh g-1). This work provides an original protocol for constructing 2D/2D material and demonstrates the FePS3@MXene composite as a potential anode material with excellent property for sodium-ion batteries.