(3-Ga2O3 is a promising ultrawide-bandgap semiconductor for next-generation power electronics and deep-ultraviolet optoelectronics, but its epitaxial growth generally requires substrate temperatures above 600 degrees C or post-annealing. Here, we report post-annealing-free heteroepitaxial growth of (201)-oriented (3-Ga2O3 thin films on c-plane sapphire using a 1064 nm ytterbium pulsed laser-assisted radio frequency magnetron sputtering process. Preferentially oriented (3-Ga2O3 films were formed at 100-400 degrees C, and a well-defined (201)-oriented heteroepitaxial film was obtained at 400 degrees C. To the best of our knowledge, this is among the lowest substrate temperatures reported for sputtering-based (3-Ga2O3 heteroepitaxy without post-annealing. RF power control experiments confirmed that increasing RF power alone did not reproduce the orientation selective growth achieved under laser irradiation. X-ray diffraction (XRD), reciprocal space mapping, phi-scan, high-resolution transmission electron microscopy (HR-TEM), and selected-area electron diffraction (SAED) confirmed the epitaxial relationship of (3-Ga2O3 (201) || Al2O3 (0001), with six in-plane rotational domains. The 400 degrees C film exhibited a sharp interface, a density of 6.34 g/cm3, and an optical bandgap of 4.95 eV. XPS showed enhanced Ga-O bonding and reduced oxygen-vacancy-related components at higher substrate temperatures. These results demonstrate laser-assisted RF sputtering as an effective low-thermal-budget route for (3-Ga2O3 heteroepitaxy on sapphire without post-annealing.
FFF (fused filament fabrication) is among the most popular additive manufacturing techniques; nevertheless, enhancing production efficiency without any degradation in mechanical properties is still a major issue. While numerous studies have investigated the influence of print speed and print temperature, the relationship between them, especially at higher print speeds, has not been researched extensively. Thus, the current research seeks to investigate the impact of high printing speed and temperature on the energy absorption capacity of FFF-printed structures in three repetitions. There was no deterioration of the energy absorption capability when printing speed was increased from 50 mm/s to 450 mm/s. At 230 degrees C, the specimen with a printing speed of 450 mm/s gave the highest total energy absorption (TEA) and specific energy absorption (SEA) of 31.4 J and 5.17 J/g, respectively, which were about 4.6% and 4.3% higher than those at a speed of 50 mm/s. In light of manufacturing time, normalized TEA and normalized SEA have risen by about 22.0% and 21.7%, respectively. The results confirm a pronounced interaction between printing speed and nozzle temperature, suggesting that high-speed FFF has the potential to increase manufacturing efficiency while maintaining and potentially improving the energy absorbing properties of PLA structures.
This study investigates the coupled evolution of gas pores and hydrogen in a spray-formed 2195 (SF-2195) aluminum alloy during solution treatment and quenching. The water-quenched (WQ) sample exhibited the highest gas porosity and the largest average pore size, followed by the air-cooled (AC) sample and then the hot-rolled (HR) sample. The quenching-induced stress gradient promoted pore expansion and coalescence, while the elevated internal pressure generated by the hydrogen trapped in pores further drove pore growth. The total hydrogen content was highest in the WQ sample (8.00 wt. ppm), exceeding that of the HR (4.87 wt. ppm) and AC (4.45 wt. ppm) samples. The significant hydrogen uptake during water quenching stemmed from the vigorous reaction between water vapor and the fresh alloy surface. The content of hydrogen trapped in pores was also the highest in the WQ sample because water quenching uniquely provided an additional hydrogen supply and induced the density of pores acting as trapping sites. These findings provide new insights into the coupled evolution of pores and hydrogen behavior during quenching and offer practical guidance for designing quenching protocols for spray-formed Al-Cu-Li alloys.
The intrinsically low strength of Au-Pt alloys remains a key obstacle to their wider use in advanced applications requiring high mechanical reliability and service durability. To address this issue, we employ first-principles calculations to systematically evaluate the effects of diverse alloying elements on their mechanical properties, aiming to identify promising candidates for alloy design. A combined analysis of solid-solution strengthening and slip barrier reveals that Re and Os, located near the boundary between the high-melting transition and platinum-group metals, together with rare-earth element Ce, exhibit an outstanding strength-ductility synergy. Notably, the strengthening induced by high-melting transition additions is primarily governed by chemical interactions, whereas lattice distortion arising from volume misfit dominates for most other solutes. Ce delivers the strongest solid-solution strengthening due to its largest size mismatch. Electronic structure analyses further reveal that solid-solution strengthening originates from the injection of additional valence electrons. Meanwhile, Ce uniquely reduces the slip barrier by weakening the local bonding character in the vicinity of the Fermi level, thereby effectively preserving the intrinsic slip capability of the Au-Pt base alloy while markedly enhancing strength. Overall, this work provides a quantitative basis and mechanistic guidance for performance optimization and ternary-alloy design of Au-Pt alloys
Bone tissue engineering (BTE) has emerged as a promising strategy for the treatment of diverse skeletal disorders. However, conventional BTE scaffolds often suffer from insufficient functional diversity, limited biological responsiveness, and inadequate spatiotemporal control over therapeutic factors and cellular responses. Ultrasound, particularly low-intensity pulsed ultrasound, has attracted increasing attention as a non-invasive and remotely controllable stimulus in regenerative medicine. By inducing mechanical, electrical, and chemical effects, ultrasound enables the regulation of stimuli-responsive biomaterials and transforms conventional scaffolds from passive structures into dynamically regulated therapeutic platforms. In this review, we summarize the fundamental mechanisms underlying ultrasound-responsive BTE and discuss the design strategies of representative scaffold biomaterials, including hydrogels, ceramics, polymers, and metals. We further highlight their applications in complex bone-related pathological conditions, such as infected bone defects, diabetic bone defects, osteoporosis, and osteosarcoma. In addition, we discuss current challenges associated with ultrasound parameter standardization, material optimization, clinical validation, and future development toward intelligent therapeutic systems. Collectively, ultrasound-responsive BTE provides a promising strategy for integrating remotely controlled acoustic stimulation with biomaterial design, advancing precise and clinically translatable bone regeneration.
