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At present, no consensus has been reached on the generation mechanism of anisotropy in materials fabricated by laser powder bed fusion (LPBF), and most attention has been focused on crystallographic texture. In this paper, an analysis and test were carried out on the hardness, defect distribution, residual stress distribution, and microstructure of WE43 magnesium alloy fabricated by LPBF. The results indicate that LPBF WE43 exhibits obvious anisotropy—the hardness HV of X–Z surface (129.9 HV on average) and that of Y–Z surface (130.7 HV on average) are about 33.5% higher than that of X–Y surface (97.6 HV on average), and the endurable load is smaller in the stacking direction Z compared to the X and Y directions. The factors contributing more to the anisotropy are listed as follows in sequence. Firstly, the defect area of the X–Y projection surface is about 13.2% larger than that of the other two surfaces, so this surface shows greatly reduced mechanical properties due to the exponential relationship between the material strength and the number of defects. Secondly, for laser scanning in each layer/time, the residual stress accumulation in the Z direction is higher than that in the X and Y directions, which may directly reduce the mechanical properties of the material. Finally, more fine grains are distributed in X–Z and Y–Z surfaces when comparing them with those in an X–Y surface, and this fine-grain strengthening mechanism also contributes to the anisotropy. After T5 aging heat treatment (250 °C/16 h), a stronger crystallographic texture is formed in the <0001> direction, with the orientation density index increasing from 10.92 to 21.38, and the anisotropy disappearing. This is mainly caused by the enhancement effect of the texture in the <0001> direction on the mechanical properties in the Z direction cancelling out the weakening effect of the defects in the X–Y surface in the Z direction. [ABSTRACT FROM AUTHOR]

To explore the size, morphology, and distribution patterns of internal pore defects in WE43 magnesium alloy formed by laser powder bed fusion (LPBF), as well as their impact on its mechanical properties, computer tomography (CT), metallographic microscopy, and scanning electron microscopy were used to observe the material's microstructure and the morphology of tensile test fractures. The study revealed that a large number of randomly distributed non-circular pore defects exist internally in the LPBF-formed WE43 magnesium alloy, with a defect volume fraction of 0.16%. Approximately 80% of the defects had equivalent diameters concentrated in the range of 10∼40 μm, and 56.2% of the defects had sphericity values between 0.65∼0.7 μm, with the maximum defect equivalent diameter being 122 μm. There were a few spherical pores around 20 μm in diameter in the specimens, and unfused powder particles were found in pore defects near the edges of the parts. Under the test conditions, the fusion pool structure of LPBF-formed WE43 magnesium alloy resembled a semi-elliptical shape with a height of around 66 μm, capable of fusion three layers of powder material in a single pass. Columnar grains formed at the edge of individual fusion pools, while the central area exhibited equiaxed grains. The "scale-like pattern" formed by overlapping fusion pool structures resulted in the microstructure of LPBF-formed WE43 magnesium alloy mainly consisting of fine equiaxed grains with a size of 2.5 μm and columnar grains distributed in a band-like manner. [ABSTRACT FROM AUTHOR]

This paper address the performance optimization of the battery heat sink module by analyzing the lattice structure of the battery heat sink module through in-depth modeling and simulation, and combining the laser powder bed fusion (LPBF)-forming technology with mechanical and corrosion resistance experiments for a comprehensive study. It is found that the introduction of the lattice skeleton significantly improves the thermal conductivity of the phase change material (PCM), realizing the efficient distribution and fast transfer of heat in the system. At the same time, the lattice skeleton makes the heat distribution in the heat exchanger more uniform, improves the utilization rate of the PCM, and helps to maintain the stability of the cell temperature. In addition, the melting of PCM in the lattice heat exchanger is more uniform, thus maximizing its latent heat capacity. In summary, by optimizing the lattice structure and introducing the lattice skeleton, this study successfully improves the performance of the battery heat dissipation system, which provides a strong guarantee for the high efficiency and stable operation of the battery, and provides new ideas and references for the development of the battery heat dissipation technology. [ABSTRACT FROM AUTHOR]

Despite the well-documented benefits of sprint interval training (SIT) and plyometric training (PT) in improving the physical fitness of soccer players, it remains unclear which of these training methods is superior for enhancing players' aerobic and anaerobic performance. Therefore, this study aimed to compare the effects of SIT and PT on physical performance measures of male soccer players. Thirty male soccer players were randomly assigned to PT (n = 10), SIT (n = 10), and an active control group (CON, n = 10). Before and after the training period, participants underwent a battery of tests consisting of vertical jump, Wingate, linear sprint with and without ball dribbling, change of direction, ball kick, and the Yo-Yo intermittent recovery level 1 (Yo-Yo IR1) tests. Both groups exhibited similar improvements in maximal kicking distance (PT, effect size [ES] = 0.68; SIT, ES = 0.92) and measures of aerobic fitness including maximum oxygen uptake (PT, ES = 1.24; SIT, ES = 1.26) and first (PT, ES = 0.85; SIT, ES = 1.08) and second (PT, ES = 0.86; SIT, ES = 0.98) ventilatory thresholds. However, PT intervention resulted in greater changes in vertical jump (ES = 1.72 vs. 0.82, p = 0.001), anaerobic power (peak power, ES = 1.62 vs. 0.97, p = 0.009; mean power, ES = 1.15 vs. 1.20, p = 0.05), linear speed (20-m, ES = -1.58 vs. -0.98, p = 0.038; 20-m with ball, ES = -0.93 vs. 0.71, p = 0.038), and change of direction ability (ES = -2.56 vs. -2.71, p = 0.046) than SIT. In conclusion, both PT and SIT demonstrated effectiveness in enhancing aerobic performance among male soccer players. However, PT yielded superior improvements in anaerobic power, vertical jump, linear speed, and change of direction performance compared to SIT. These findings suggest that PT may offer additional benefits beyond aerobic conditioning., (© Journal of Sports Science and Medicine.)