作者机构：
[刘武; 张彦; 陈勇; 邱长军] Mechanical Engineering School, University of South China, Hengyang;421001, China;[刘武; 张彦; 陈勇; 邱长军] 421001, China
通讯机构：
[Qiu, C.] M;Mechanical Engineering School, University of South China, Hengyang, China
关键词：
激光快速成形;显微硬度;抗拉强度;断后伸长率;显微组织
摘要：
采用5 k W横流CO2激光器在Q235基材上快速成形三种不同成分的304不锈钢粉末,分别为标准304不锈钢粉末,添加CH化合物的304不锈钢粉末,添加CH化合物以及Ni60A的304不锈钢粉末,通过试验方法观察三种不同成分的304不锈钢激光快速成形试件的的显微组织,研究其综合力学性能.结果表明,在304不锈钢粉末内添加CH化合物能显著提高激光快速成型试件的显微硬度,抗拉强度和断后伸长率,显微组织得到细化;而同时添加CH化合物及Ni60A的试件的抗拉强度及显微硬度得到更大的提高,但断后伸长率却有一定程度的降低.
摘要：
We report the synthesis of ceria nano-octahedrons using a simple yet efficient hydrothermal technique free of surfactant and template. A comprehensive microscopic characterization reveals that the nano-octahedrons exposed with eight {1 1 1} planes have shape corners and well-defined edges at the nanoscale. Atomic-resolution imaging uncovers that a couple of atomic layers are disappeared at corner, the atomic density of oxygen is reduced at surface, and there occur stacking faults inside the nano-octahedrons, which should have implications for our understanding of catalytic activity of ceria. We also propose a growth mechanism for the nano-octahedrons and provide an explanation to the easy formation of nano-octahedrons with the eight {1 1 1} facets. (C) 2014 Elsevier B.V. All rights reserved.
期刊：
Journal of Physical Chemistry C,2014年118(8):4437-4443 ISSN：1932-7447
通讯作者：
Chen, Chunlin
作者机构：
[Fan, Xiangfang; Chen, Yong; Qiu, Changjun] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.;[Chen, Chunlin; Lv, Shuhui; Wang, Zhongchang; Chen, Yong] Tohoku Univ, Adv Inst Mat Res, WPI Res Ctr, Aoba Ku, Sendai, Miyagi, Japan.;[Chen, Chunlin] Tohoku Univ, Adv Inst Mat Res, WPI Res Ctr, Aoba Ku, 2-1-1 Katahira, Sendai, Miyagi, Japan.
通讯机构：
[Chen, Chunlin] T;Tohoku Univ, Adv Inst Mat Res, WPI Res Ctr, Aoba Ku, 2-1-1 Katahira, Sendai, Miyagi, Japan.
摘要：
We investigate, by a systematic first-principles calculation, the surface energies of ceria {100} crystal planes with adsorption of 13 kinds of nonmetallic elements and nine kinds of metallic elements. We predict theoretically that adsorption of nonmetallic B, C, F, Si, P, S, Cl, Br, OH, and I and metallic Sr, La, Mg, Na, K, Y, Ca, and Ba can stabilize the ceria {100} planes through lowering their surface energies. Experimentally, we purposely select KOH as a mineralizing agent by taking into account the calculated surface energies and the factors in hydrothermal synthesis, and demonstrate a successful production of cube-shaped ceria nanoparticles of high purity via carefully optimizing the synthesis parameters. Further comprehensive transmission electron microscopy study identifies all the exposure planes of the cube-shaped ceria nanoparticles as the uniform {100} crystal planes. As a result of this unique morphology, the nanoparticles are found to show markedly enhanced UV-absorption capability as compared to either octahedron-shaped ceria nanoparticles or bulk ceria.
摘要：
We report the fabrication of the 304 stainless steel by the laser rapid prototyping harmonized with high-frequency micro-forging and demonstrate that both microstructure and properties of the prepared samples can be enhanced significantly. Structurally, we find that the large regular dendritic microstructure can be broken into pieces and that the internal defects are to some extent eliminated. Moreover, grains are refined remarkably. As a consequence of such structural modification, mechanical properties are found to be enhanced considerably by demonstrating a much broader fluctuation in tensile strength, a marked increase in tensile and yielding strength, and a drastic enhancement in surface hardness by 76% after the micro-forging. Further calculations reveal that the defect region is shrunken substantially after micro-forging. Detailed analysis of fractures in the tensile samples provides convincing evidence that plastic properties can be improved as well by the micro-forging.
作者机构：
[陈平虎; 邱长军] School of Mechanical Engineering, Nanhua University, Hengyang 421001, China;[陈勇] College of Materials Science and Engineering, Chongqing University, Chongqing 400030, China;[龙冲生] Nuclear Power Institute of China, Chengdu 610041, China
通讯机构：
[Qiu, C.] S;School of Mechanical Engineering, Nanhua University, China
作者机构：
[邱长军; 陈平虎] School of Mechanical Engineering, Nanhua University, Hengyang 421001, China;[龙冲生] Nuclear Power Institute of China, Chengdu 610041, China;[陈勇] College of Materials Science and Engineering, Chongqing University, Chongqing 400030, China
通讯机构：
[Qiu, C.-J.] S;School of Mechanical Engineering, Nanhua University, China
