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In this paper, Al-CaB6 alloys were prepared by in situ melt reaction. The CaB6 particles through in situ growth are cubic with a regular shape, evenly distributed in the Al matrix. By edge-to-edge matching model’s calculation, mismatch between CaB6 particles and α-Al was ~2.34%, which is less than 6%, so CaB6 can serve as the core of α-Al nucleation. When the amount of CaB6 addition reaches 6 wt.%, hardness of the Al-CaB6 alloy reached 34.4 HV. Besides, CaB6-particle reinforced hypereutectic Al-Si composites were prepared, and the positive influence of CaB6 particles on microstructure and properties of hypereutectic Al-Si composites was studied. The CaB6 particles show significant effect on the modification of primary silicon. Owing to the addition of CaB6 particles, the hardness of hypereutectic Al-Si alloys increased and the hardness of Al-18Si-CaB6 reached 95.1 HV. The electrochemical test of the manufactured composites revealed that the corrosion resistance of Al-18Si-CaB6 composites improved as the amount of CaB6 particle content increased. This work serves as a reference for the investigation of Al and Al-Si composites reinforced with ceramic particles. [ABSTRACT FROM AUTHOR]

For atomically thin two-dimensional materials, variations in layer thickness can result in significant changes in the electronic energy band structure and physicochemical properties, thereby influencing the carrier dynamics and device performance. In this work, we employ time- and energy-resolved photoemission electron microscopy to reveal the ultrafast carrier dynamics of PdSe 2 with different layer thicknesses. We find that for few-layer PdSe 2 with a semiconductor phase, an ultrafast hot carrier cooling on a timescale of approximately 0.3 ps and an ultrafast defect trapping on a timescale of approximately 1.3 ps are unveiled, followed by a slower decay of approximately tens of picoseconds. However, for bulk PdSe 2 with a semimetal phase, only an ultrafast hot carrier cooling and a slower decay of approximately tens of picoseconds are observed, while the contribution of defect trapping is suppressed with the increase of layer number. Theoretical calculations of the electronic energy band structure further confirm the transition from a semiconductor to a semimetal. Our work demonstrates that TR- and ER-PEEM with ultrahigh spatiotemporal resolution and wide-field imaging capability has great advantages in revealing the intricate details of ultrafast carrier dynamics of nanomaterials.

Optoelectronic synapses are currently drawing significant attention as fundamental building blocks of neuromorphic computing to mimic brain functions. In this study, a two-terminal synaptic device based on a doped PdSe 2 flake is proposed to imitate the key neural functions in an optical pathway. Due to the wavelength-dependent desorption of oxygen clusters near the intrinsic selenide vacancy defects, the doped PdSe 2 photodetector achieves a high negative photoresponsivity of -7.8 × 10 3 A W -1 at 473 nm and a positive photoresponsivity of 181 A W -1 at 1064 nm. This wavelength-selective bi-direction photoresponse endows an all-optical pathway to imitate the fundamental functions of artificial synapses on a device level, such as psychological learning and forgetting capability, as well as dynamic logic functions. The underpinning photoresponse is further demonstrated on a flexible platform, providing a viable technology for neuromorphic computing in wearable electronics. Furthermore, the p-type doping results in an effective increase of the channel's electrical conductivity and a significant reduction in power consumption. Such low-power-consuming optical synapses with simple device architecture and low-dimensional features demonstrate tremendous promise for building multifunctional artificial neuromorphic systems in the future., (© 2023 Wiley‐VCH GmbH.)