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In situ neutron diffraction experiments have been performed to investigate the deformation mechanisms on CoCrFeNi high entropy alloys (HEAs) with various amounts of doped Cu. Lattice strain evolution and diffraction peak analysis were used to derive the stacking fault probability, stacking fault energy, and dislocation densities. Such diffraction analyses indirectly uncovered that a lower degree of Cu doping retained the twinning behavior in undoped CoCrFeNi HEAs, while increasing the Cu content increased the Cu clusterings which suppressed twinning and exhibited prominent dislocation strengthening. These results agree with direct observations by transmission electron microscopy. [ABSTRACT FROM AUTHOR]

III–V Indium Arsenide (InAs) nanowire photodetectors have attracted intensive research attention due to their high carrier mobility, direct and narrow bandgap, and nanoscale dimensions, offering immense potential in nanoscale optoelectronics, particularly for applications in photonic integrated circuits. Despite extensive studies on the properties of InAs nanowires, their photoresponse remains intricate, displaying bipolar behavior (i.e., positive and negative photoresponse) within the same device under varying conditions. However, the underlying driving mechanism remains unclear. In this work, we have systematically studied the transition between the negative photoresponse and positive photoresponse in the InAs nanowire photodetector under different conditions. We found the bipolar photoresponse is directly related to the occupation status of the surface trap states, and it could be effectively regulated by the gate voltage, power intensity, as well as the illumination duration. Furthermore, we developed a waveguide-integrated InAs nanowire photodetector using electron photoresist with an optical loss as low as 0.122 dB/μm. This achievement underscores its potential for application in photonic integrated photodetectors, laying the groundwork for future integration of InAs nanowire photodetectors into photonic integrated circuits. [ABSTRACT FROM AUTHOR]

Acoustic emission, AE, spectroscopy identifies dislocation avalanches and crack propagation in high-purity Cu with self-stabilized dislocation networks. These samples were produced by additive manufacturing where thermal gradients form cellular structures. These structures confine avalanches of dislocation movements (∼confined dislocations) with an energy exponent ε = 1.82 ± 0.04. Free dislocation movement follows force-integrated mean-field behavior with ε = 1.6 ± 0.02. Additional crack propagation under tension exhibits a critical failure exponent of ε = 1.45 ± 0.01. These three mechanisms combine to generate sample failure under tension. We use this example to demonstrate how different avalanche mechanisms can be disentangled in AE spectroscopy of additive manufactured metal and how the specific self-stabilized dislocation networks influence these avalanche dynamics. [ABSTRACT FROM AUTHOR]