关键词： ODS-HT9钢   纳米Y2O3含量   显微结构   性能  

摘要： 为了研究纳米Y2O3对HT9钢的显微结构和力学性能的影响,采用粉末冶金工艺,制备了纳米Y2O3含量为0.1%~0.9%的ODS-HT9钢样品,测定了样品的抗拉强度、伸长率、维氏硬度等力学性能,利用透射电子显微镜(TEM)观察和分析了样品中纳米Y2O3颗粒的分布状况、形状和相结构,利用扫描电子显镜(SEM)观察了样品拉伸断口的形貌。研究表明,球磨和热压烧结后,纳米Y2O3颗粒能够均匀地分布于基体中,相结构和形状未发生明显变化。弥散分布的纳米Y2O3硬质颗粒,具有明显的弥散强化作用,导致ODS-HT9钢的抗拉强度和维氏硬度随Y2O3含量的增加而显著增加,伸长率显著降低。Y2O3含量低于0.7%时,样品以韧性断裂为主,进一步增加含量,断裂方式将由韧性断裂转变成脆性断裂。纳米Y2O3含量为0.3%~0.5%的ODS-HT9钢,抗拉强度达到了913~936 MPa,伸长率为10.7%~11.2%,具有良好的综合力学性能。本文研究结果有助于ODS-HT9钢高温性能的研究及其在反应堆中的实际应用。

关键词： 艺术鉴赏能力   材料微结构   专家评委   仪器使用   微观世界   大赛   参赛作品   参赛者  

摘要： 材料之美不仅体现在宏观,也表现在其微观组织。为了让更多材料人欣赏到美轮美奂的材料组织,培养探索微观世界的兴趣,提高仪器使用水平与艺术鉴赏能力,第六届材料微结构大赛经过多番比拼已于日前圆满落幕。本次大赛征稿阶段共收到来自104家单位的392份参赛作品,感谢所有参赛者的来稿!评选阶段超过1.5万人次投票,5位专家打分点评。感谢所有专家评委的支持!感谢所有读者的投票!

关键词： Microstructural materials   Material design   Deep learning   Generative adversarial network   Convolutional neural network  

摘要： Due to their designable properties, microstructural materials have emerged as an important class of materials that have the potential for used in a variety of applications. The design of such materials is challenged by the multifunctionality requirements and various constraints stemmed from manufacturing limitations and other practical considerations. Traditional design methods such as those based on topological optimization techniques rely heavily on high-dimensional physical simulations and can be inefficient. In addition, it is difficult to impose geometrical constraints in those methods. In this work, we propose a deep learning model based on deep convolutional generative adversarial network (DCGAN) and convolutional neural network (CNN) for the design of microstructural materials. The DCGAN is used to generate design candidates that satisfy geometrical constraints and the CNN is used as a surrogate model to link the microstructure to its properties. Once trained, the two networks are combined to form the design network which is utilized to for the inverse design. The advantages of the method include its high efficiency and the simplicity in handling geometrical constraints. In addition, no high-dimensional sensitivity simulations are required. The performance of the method is demonstrated on the design of microstructural materials with desired compliance tensor, subject to specified geometrical constraints.

关键词： Fatigue   Multiscale modelling   Ferritic steels   Microstructure   Fracture mechanics  

摘要： This paper presents a modelling strategy for accurately predicting the high-cycle fatigue strengths of ferritic steels based on only microstructural information, tensile properties, and loading conditions, without any adjustable material constants. The most important feature of the proposed strategy is that total fatigue life is estimated from crack growth life alone. In preparation for model development, the opening/closure behaviour of a microstructurally small crack was quantified from a huge amount of image data obtained by combining an automatic in-situ observation system and a digital image correlation technique. In the proposed modelling strategy, the entire model comprises three sub-models, for: (i) a macroscopic finite element analysis, (H) microstructure, and (Hi) crack growth. The model was strictly validated against the results of experiments performed on three different steels under three different loading conditions (specimen geometries and load ratios). Although the experimental fatigue life results exhibited wide variation, the predicted and experimental data were accurately matched over the entire range. The results demonstrate that the fatigue life of steels under high-cycle fatigue can be accurately predicted from crack growth life alone. Furthermore, the proposed strategy is capable of effectively explaining the dependence of fatigue strength on microstructure and loading conditions based on the fracture mechanics.

关键词： 断路器   机械特性   调试  

摘要： 分析常规弹簧机构断路器机械特性涉及的各项重要技术参数特点,结合现场检修经验探讨其调试。

关键词： 艺术鉴赏能力   材料微结构   仪器使用   微观世界   大赛   培养探索   美轮美奂   微观组织  

摘要： 材料之美不仅体现在宏观,也表现在其微观组织。为了让更多材料人欣赏到美轮美奂的材料组织,培养探索微观世界的兴趣,提高仪器使用水平与艺术鉴赏能力,特此举办第六届材料微结构大赛。

关键词： 可视化技术   可视化软件   三维空间结构   材料微结构   必需条件   Matlab   微观结构  

摘要： 材料是科技文明发展的必需条件之一,研究材料的微观结构有助于加深人们对材料的认识。且伴随着可视化技术的发展,人们可以借助于可视化软件平台将材料的微观结构进行展现。利用Matlab的可视化技术,展示Si C的三维空间结构、BN的微观结构与性能之间的部分联系,以及追踪Ti Al3最大团簇的形成过程。

关键词： Nanomaterials   Hydrothermal synthesis   Crystal structure   Microstructural model  

摘要： New hybrid compound FeNa0.5H1.5MoO5 was synthetized by hydrothermal method, an ecofriendly, simple and efficient process. The structural/nanostructural and morphological properties of the synthetized particle were determined by means of various characterization technics. Combined scanning electron microscopy and Energy dispersive X-ray analysis revealed spheroidal morphology of the nanoparticles and permitted to reach the effective atomic ratio. Thus, we determined the composition. Fourier Transform Infrared Spectroscopy analysis allowed to stoichiometric estimate the force constants of Mo-O and Fe-O bonds, that strongly depend on ionic radius and crystallographic network. X-ray diffraction results showed a pure monoclinic phase with preferential orientation growth along the (1 1 0) direction. The crystallite sizes and the micro-strain values were estimated and discussed according to the considered models Based on Rietveld refinement, an optimized 3D structure was proposed, where MoO4 tetrahedral sites alternate with FeO6 octahedral ones. This arrangement leads to a large tunnel-like interstitial space that favors ions diffusion. Consequently, the new hybrid compound FeNa0.5H1.5MoO5 is suitable for applications involving charge transport, such as solid electrolytes. As well, this study can pave the way to highlight the relation between structure and properties in Na-ion storage/diffusion electrochemical applications.

关键词： Anisotropic plasticity   Microstructural heterogeneity   Additive manufacturing   Powder bed fusion   High-manganese steel   Twinning-induced plasticity   Crystal plasticity modeling   Physics-based constitutive modeling   Representative volume element  

摘要： Additively manufactured (AM) metallic parts exhibit substantially different microstructures compared to those that are conventionally produced. Characterization studies have revealed that the microstructure of as-built AM metallic materials is highly heterogeneous in many respects. The strongly anisotropic mechanical response under plastic deformation observed in AM metals, compared to their conventionally manufactured counterparts, lies in the aforementioned inherent microstructural disparities. In this study, we have focused on a high-manganese steel (HMnS) processed by laser powder bed fusion (LPBF), which exhibits twinning-induced plasticity (TWIP). The as-built microstructure is carefully characterized by electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. To unfold the potential of metal additive manufacturing, it is essential to understand the microstructure of AM products and its connection with the mechanical properties by means of numerical modeling and simulation. The mechanical response of AM components under plastic deformation is highly complex and its simulation requires advanced modeling and numerical methods. In the present study, in order to simulate the anisotropic plasticity of the LPBF-HMnS, we used the full field method for computational polycrystal homogenization combined with physics-based crystal plasticity constitutive and statistical microstructure modeling. The impact of different process-induced microstructural heterogeneity characteristics on macroscopic strain hardening behavior of the material has been comprehensively and systematically investigated. Finally, it has been argued why the chosen AM material with the selected processing parameters and chemical composition represented an ideal candidate for a generic assessment of the anisotropic polycrystal plasticity due to microstructural heterogeneity. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights