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P-type Fe3CoSb12-based skutterudite thin films are successfully fabricated, exhibiting high thermoelectric performance, stability, and flexibility at medium-to-high temperatures, based on preparing custom target materials and employing advanced pulsed laser deposition techniques to address the bonding challenge between the thin films and high-temperature flexible polyimide substrates. Through the optimization of fabrication processing and nominal doping concentration of Ce, the thin films show a power factor of >100 μW m−1 K−2 and a ZT close to 0.6 at 653 K. After >2000 bending cycle tests at a radius of 4 mm, only a 6 % change in resistivity can be observed. Additionally, the assembled p-type Fe3CoSb12-based flexible device exhibits a power density of 135.7 µW cm−2 under a temperature difference of 100 K with the hot side at 623 K. This work fills a gap in the realization of flexible thermoelectric devices in the medium-to-high-temperature range and holds significant practical application value. The authors fabricate p-type Fe3CoSb12-based skutterudite films exhibiting high thermoelectric performance, stability, and flexibility at medium-to-high temperatures, based on preparing custom target materials and pulsed laser deposition techniques. [ABSTRACT FROM AUTHOR]

The propagation of hydraulic fractures is highly influenced by the geological structure of the reservoir in unconventional reservoirs, such as natural fractures. In this paper, a new fluid–solid coupling dynamic model was built which presents the failure mechanism of hydraulic fracture with pre-existing simple and complex natural fractures. The cohesive element method and the maximum principal stress fracture criterion were used in the new model. An analysis was conducted to investigate the impact of various factors, including encounter angle, in situ stress, elastic modulus, and Poisson's ratio, on the propagation of hydraulic fractures. The simulation results indicate that the encounter angle and the in situ stress are the main factors affecting the fracture morphology. When the encounter angle and the in situ stress difference are small, hydraulic fractures propagate along natural fractures. When the elastic modulus is small, it is advantageous for the advancement of both hydraulic and natural fractures. The Poisson's ratio has a slight effect on the fracture propagation pattern. [ABSTRACT FROM AUTHOR]

In this work, silica‐based ceramic cores with alumina as a mineralizer were prepared via an injection molding method, and the effects of alumina on the microstructural evolution and properties at 1450°C (simulating the process of equiaxed castings) and 1550°C (simulating the process of columnar/single crystal castings) were investigated. It was found that alumina promoted the cristobalite crystallization of fused silica refractory during sintering but inhibited the devitrification rate in the subsequent heating. The flexural strength of silica‐based ceramic cores at an ambient temperature and 1450°C improved with an increasing alumina content, whereas the opposite trend appeared at 1550°C. The creep resistances of silica‐based cores were improved significantly and then slightly deteriorated with an increasing alumina content from 5% to 20%, depending on the competition effects of alumina hindering the viscous flow of liquid silica (favorable), but suppressing the devitrification rate (unfavorable). The results of this work show that silica‐based cores need to follow different compositional design principles for equiaxed and columnar/single‐crystal turbine blade castings. [ABSTRACT FROM AUTHOR]

Al-4.5wt.%Cu alloy has been directionally solidified at constant and abruptly changing withdrawal rates, respectively. The effects of the withdrawal rate on solidification microstructure, primary dendrite arm spacing (PDAS) and liquid solute distribution in front of the solid-liquid interface were investigated. The experimental results for the PDAS at a constant withdrawal rate agree well with the values calculated by the Hunt, Trivedi and Hunt-Lu models. At an abrupt change in the withdrawal rate, the maximum to minimum ratio of the PDAS at a given solidification parameter, i.e. λ1max/λ1min, is more than 2, and the PDAS values are remarkably history-dependent. Further, the liquid-solute distribution curve based on theoretical calculation shows that the larger the initial withdrawal rate is, the smaller the minimum of liquid solute concentration in front of the solid-liquid interface is after the abrupt change in withdrawal rate.

The directionally solidifi ed microstructure of Sn-16%Sb hyperperitectic alloy has been investigated at various solidifi cation rates using a high-thermal gradient directional solidifi cation apparatus. The results indicate that the solidifi cation microstructure consists of hard primary intermetallic SnSb phase embedded in a matrix of soft peritectic β-Sn phase. The primary SnSb phase exhibits faceted growth with tetragonal or trigonal shapes. At the same time, the primary SnSb phase is refi ned with an increase in the solidifi cation rate and dispersed more uniformly in the matrix of β-Sn phase. The volume fraction of the SnSb phase fi rstly decreases and then increases when the solidifi cation rate increases in directional solidifi cation of Sn-16%Sb hyperperitectic alloy.