基于APT对镍基高温合金纳米结构和化学成分研究

在镍基高温合金的研究中,原子探针层析技术(APT)可以提供独特定量的高质量信息。采用原子探针LEAP4000X Si对镍基高温合金的纳米结构和化学成分进行研究,主要包括以下4个方面的内容:γ'相纳米结构(形貌、尺寸、数量密度和体积分数)、微量难熔金属元素相分配(元素原子浓度和分配系数)、γ/γ'共格界面(界面宽度和元素界面偏聚)及原子簇聚和有序化(局部径向分布函数)。     

3D bioprinting: Materials,processes, and applications

Ageing population and new diseases are requiring the development of novel therapeutical strategies. 3D bioprinting an novel application domain of additive manufacturing emerged as a potential transformative strategy for tissue engineering and regenerative medicine. This paper introduces the concept of 3D bioprinting, discussing in detail key requirements of bio-inks and main materials used to encapsulate cells. Recent advances related to the use of smart materials and the concept of 4D printing is also discussed. Main 3D bioprinting techniques are described in detail and key limitations highlighted. Successful cases, demonstrating the relevance of 3D bioprinting are also presented. Finally, the paper addresses the main research challenges and future perspectives in the field of 3D bioprinting.     

In Situ X-ray Tomography and 3D X-ray Diffraction Measurements of Cemented Granular Materials

JOM - In situ x-ray tomography and three-dimensional (3D) x-ray diffraction analysis have been combined to investigate the mechanical behavior of noncemented and lightly cemented quartz...     

Atom Probe Tomography Study of Fe Segregation at Phase Interface in Zr–2.5Nb Alloy

β-Nb is a typical second phase in Zr–Nb-based alloys used as fuel claddings in water-cooled nuclear reactors. The segregation of alloying element Fe may affect the corrosion resistance of Zr–Nb-based alloys. In this work, the Fe segregation at the interface between β-Nb phase and α-Zr matrix in Zr–2.5 Nb alloy was studied using atom probe tomography and focused ion beam. The results suggested that the Fe concentration was much lower than Nb concentration in α-Zr matrix, while Fe selectively segregated at the β-Nb/α-Zr phase interface, leading to a Fe concentration peak at some interfaces. The peak Fe concentration varied from 0.4 to 1.2 at.% and appeared at the position where Zr concentration was approximately equal to Nb concentration. The selective segregation of Fe should be affected by the heat treatment and structure defects induced by cold rolling.     

From Historical Backgrounds to Recent Advances in 3D Characterization of Materials: An Overview

Two-dimensional pictures and x-ray diffraction (XRD) patterns have for a long time been the standard techniques most frequently used to analyze a material structure. In the past decades, owing to advances in imaging and computer technology, three-dimensional (3D) techniques have provided new insights into how phase distribution, crystallographic interfaces and defect arrangements contribute to build a material structure. Moreover, theoretical modeling is now able to disclose a more accurate structural simulation with the support of 3D characterization. In this work, a concise overview of the major 3D imaging techniques is presented to update the reader with the main related achievements in automated serial sectioning, focused ion beam/scanning electron microscopy (FIB/SEM) and x-ray microtomography (microCT). Examples addressed in the literature for engineering materials illustrate each technique.     

Characterization of Cracking Mechanisms of Carbon Anodes Used in Aluminum Industry by Optical Microscopy and Tomography

The objective of this work is to understand the different mechanisms of crack formation in dense anodes used in the aluminum industry. The first approach used is based on the qualitative characterization of the surface cracks and the depth of these cracks. The second approach, which constitutes a quantitative characterization, is carried out by determining the distribution of the crack width along its length as well as the percentage of the surface containing cracks. A qualitative analysis of crack formation was also carried out using 3D tomography. It was observed that mixing and forming conditions have a significant effect on crack formation in green anodes. The devolatilization of pitch during baking causes the formation and propagation of cracks in baked anodes in which large particles control the direction of crack propagation.     

Nanoscale phase field microelasticity theory of dislocations: model and 3D simulations

The first Phase Field model of evolution of a multi-dislocation system in elastically anisotropic crystal under applied stress is formulated. The model is a modification and extension of our Phase Field Microelasticity approach to the theory of coherent phase transformations. The long-range strain-induced interaction of individual dislocations is calculated exactly and is explicitly incorporated in the Phase Field formalism. It also automatically takes into account the effects of “short-range interactions”, such as multiplication and annihilation of dislocations and a formation of various metastable microstructures involving dislocations and defects. The proposed 3-dimensional Phase Field model of dislocations does not impose a priori constraints on possible dislocation structures or their evolution paths. Examples of simulation of the FCC 3D system under applied stress are considered.     

铑铱金属及其它难溶贵金属物料的溶解

快速高效地溶解金属铑、铱及其它贵金属难溶物料,是贵金属冶金中非常重要的问题。介绍了难溶金属及不同品位、成分复杂的各种贵金属难溶物料的溶解方法。     

Abstracts from International Journal of Minerals, Metallurgy and Materials

Inclusion variations and calcium treatment optimizationin pipeline steel productionLIU Jianhua, WU Huajie, BAO Yanping, and WANG Min Abstract SiCa line and SiCaBaFe alloy were injected into liquid pipe-line steel at the end of LF refining as calcium treatment, and     

Determination of the Mg-Rich Phase Boundary of the Binary Mg-Nd Phase Diagram by Means of Atom Probe Tomography

The present paper relates the investigation of the Mg-rich side of the binary Mg-Nd phase diagram by means of Atom Probe Tomography (APT). The solid solubility of Nd in Mg at the temperatures 400, 480, 520 °C has been measured. The results of the current investigation demonstrate that the solid solubility of Nd in Mg is much larger than is usually supposed and presented in more recent Mg-Nd phase diagrams. The data presented in this work can be used for further thermodynamic calculations in order to interpolate the phase boundary between temperature points.     

Abstracts from International Journal of Minerals, Metallurgy and Materials

Kinetics of the electrochemical process of galena electrodes in the diethyldithiocarbamate solution CHENG Lili, SUN Tichang, LUO Xianping, and WANG Dianzuo Abstract The electrochemical process of galena in a pH 12.8 buffer     

Abstracts from International Journal of Minerals, Metallurgy and Materials

<正>Effects of nano-sized Ag reinforcing particulates on the microstructure of Sn-0.7Cu solder jointsTAI Feng, GUO Fu, XIA Zhidong, LEI Yongping, and SHIYaowuAbstractComposite solders were prepared by mechanically dispersing different volumes of nano-sized Ag particles into the Sn-0.7Cu eutectic solder.