The wide Mg alloy sheets produced by hot extrusion usually can easily form an inhomogeneous texture, resulting in anisotropic mechanical properties and poor formability. However, few studies have been carried out on the bulk texture investigation at different areas of as-extruded Mg alloy sheets, especially the Mg alloys with different alloying elements. In this work, the effect of Al on the bulk texture and mechanical properties at different areas for three wide Mg-Al-Zn alloy sheets with different Al contents (Mg-3Al-0.5Zn, Mg-8Al-0.5Zn and Mg-9Al-0.5Zn) are mainly investigated by neutron diffraction. The results showed that a strong and uneven basal texture was formed in the Mg-3Al-0.5Zn sheet. Meanwhile, the intensity of the basal texture was significantly weakened due to the numerous fine precipitates of Mg₁₇Al₁₂ particles, with the Al content increasing, which hinder the grain growth during extrusion, while fine recrystallized grains have a more random orientation. The enhanced tensile properties in Mg-8Al-0.5Zn and Mg-9Al-0.5Zn alloy sheets are ascribed to the cooperation effect of a refined microstructure, precipitates and weakened basal texture. Among the three Mg alloy sheets, the Mg-8Al-0.5Zn alloy sheet has a yield strength of about 270 MPa, an ultimate tensile strength of about 330 MPa and ultimate elongation of about 16% in the extrusion direction, which possesses the most excellent comprehensive mechanical properties.

Engineering Materials Diffractometer (EMD) is included in Project Phase Two of the China Spallation Neutron Source (CSNS), which focuses on strain scanning, thermomechanical investigation and phase transformation analysis under different sample environments, as well as other novel industrial research for engineering materials. After a comprehensive analysis and optimization, the total length of EMD is designed to be 51.5 m where the primary and secondary flight path are 49.5 m and 2 m, respectively. The neutron optical components mainly consist of insert guides, curved guides, bandwidth choppers, straight guides (including both straight and focusing sections), slits, collimators, detectors, etc. Particularly, an individual 9 m logarithmic spiral focusing guide to optimize instrument performance was confirmed by Monte Carlo simulation with the McStas package. Under the target power of 100 kW, for high resolution mode, the resolution Δ d/d is about 0.25% for 2θ=90^∘ and the neutron flux is 4.5× 10⁶ n/cm²/s at the sample position; for high intensity mode, the neutron flux is 1.4× 10⁷ n/cm²/s and the resolution is about 0.50%. The high instrument flexibility could allow and extend a broad of applications in materials science and engineering fields in the future. This paper will discuss the details of EMD instrument optical system design especially the focusing guide and combinations of slits.

英国散裂中子源(ISIS)在工程材料中子衍射领域有着十余年丰富的研究经验, 最为典型的衍射谱仪之一的Engin-X在材料、加工等方向有着广泛应用, 包括残余应力分布测量、金属相变分析、微观力学研究等. Engin-X通过设置红外加热型高温炉配套材料试验机的样品环境以实现中子衍射原位高温力学实验, 目前原位实验中高温炉最高设计温度可达1100 ℃. 通过优化高温炉反射罩形状、布局、反射涂层, 以及合理设置反射挡板等措施(例如采用一种椭圆-圆组合形状的反射罩), 可实现更优的光线聚焦效果. 模拟计算得知样品的能量吸收可提高109%以上, 最终高温可达1400 ℃. 相关研究有望拓展Engin-X中子衍射技术在材料研究领域的应用, 同时也为中国散裂中子源(CSNS)工程材料衍射谱仪样品环境设计提供借鉴经验.

In internet of vehicle (IOV) system, vehicle-to-vehicle (V2V) data transmission is influenced by multipath interference, which often causes bad consequences. In order to improve the data transmission reliability, a new estimate algorithm is proposed, that is an evaluation algorithm for V2V communication reliability based on sample judgment and balanced modulation. This study structures a transmission channel model of V2V in IOV, and analyses the characteristics of multipath transportation of communication channel. The simulation result indicates that the above-mentioned reliability estimate method can get an even better accuracy of V2V communication transmission and better effect of communication channel balance. Meanwhile, it can also reduce the error code ratio of the communication and improve the communication quality.

Carrier multiplication, that is, generation of multiple excitons by single photons is observed for the first time directly in ultrafast photocurrent of films of coupled PbSe quantum dots excited by sub-picosecond laser pulses.