摘要：
Shielding materials, Fe-W-C alloy (wt.%) with the different tungsten content and higher density was successfully prepared by powder metallurgical processing sequences comprising of mechanical alloying, compaction and liquid phase sintering. The process parameters such as mechanical alloying conditions, compaction pressure, sintering atmosphere, and sintering schedule were optimized to achieve the desired sintered density. The synthesized alloy was characterized for the evolution of microstructure, phases and mechanical properties using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), tensile testing, X-Ray diffraction (XRD), etc. The sintered alloy was found to comprise with the matrix phase a-Fe and the binding phases such as Fe2W2C, Fe6W6C and Fe2W. Extensive, EDS analysis revealed the distribution of Fe, Wand C element in the matrix phase, binding phase and blocky binding zone, respectively. W contents altered the density and microstructure of the alloy significantly. The tensile strength and ductility of the as-sintered Fe-W-C alloy was found to be 345 MPa and 17.5%, respectively. SEM characterization of the tensile-fracture surface showed mixed mode of fracture, i.e. ductile and brittle fracture in alpha-Fe and W particles, respectively. The gamma-ray shielding performance of the alloys was carried out by BH1326 gamma-ray shielding tester, and the half-attenuation thickness of alloy containing 16% W was the minimum, about 8.5 mm. The results of neutron shielding simulation show that the transmission of the neutron shield of alloy Fe-W-C containing 16% W was the minimum. (C) 2020 Published by Elsevier B.V.
摘要：
By using vacuum sintering method, the shielding materials made of iron-tungsten-carbon-boron (Fe-W-C-B) alloys with different boron (B) contents were prepared. The influences of different B contents on mechanical properties, shielding performance and microstructures of the alloys were investigated. The research results showed that with increasing B content, the fracture of alloys changed from plastic to brittle fractures and the higher the B content was, the more serious the brittle fracture. Moreover, the content of brittle amorphous phase FeWB increased and therefore the hardness and density of alloys increased at first and then reduced. When the B content was 2.5%, the alloy phase was mainly composed of Fe2B, Fe3(C, B) and alpha-Fe phases, with compact microstructure, shown as continuous network microstructure and tiny, long, round rod-like microstructure. In this case, the density, tensile strength and hardness of alloys were 10.05 g/cm(3), 410 MPa and 468 HV, respectively. The gamma-ray shielding performance of the alloy reduced at first, then increased and finally declined with the increase of B contents. When the B content was 1.5%, the half-value thickness reached to the minimum (about 6.36 mm). The transmittance of neutron shields reduced at first and then increased in a low-energy zone (0-4 MeV). When the B content was 2.5%, the alloys showed the lowest transmittance about 0.10842. (C) 2019 Elsevier B.V. All rights reserved.
通讯机构：
[Xiao, Weiwei] U;[Deng, Hua] C;Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;CNNC Jianzhong Nucl Fuel Corp, Yibin 644000, Sichuan, Peoples R China.
关键词：
High temperature oxidation;Mechanical properties;Sputtered TiN coating;Substrate bias
摘要：
This study is aimed to investigate the influence of substrate bias on mechanical properties and high temperature oxidation of sputtered TiN coating which is prepared on the surface of Zr-4 alloy. The microstructures of coatings were characterized by using scanning electron microscope (SEM) and X-ray diffractometer (XRD). The thicknesses of coatings were detected by examining the cross-sectional SEM image. The adhesion property was tested by using scratch testing. The residual stress was measured by using the XRD method. The tensile property was evaluated by standard tensile test. And the high temperature oxidation performance in air condition was also assessed. It was revealed that substrate bias has a significant influence on crystalline structure, surface micromorphology, thickness, adhesion strength, and residual stress. Nevertheless, tensile property and high temperature oxidation performance are affected by substrate bias indistinctively. From the cross-sectional SEM image, it can be found that thicker coating can be obtained in unit time with a lower substrate bias. The adhesion property does not vary monotonically with increasing negative substrate bias and the coating deposited with -100 V possesses highest critical load. The sputtered TiN coatings demonstrate a compressive residual stress and the magnitude of residual stress of coatings prepared with -200 V and -300 V is higher than that of coatings prepared with -50 V and -100 V. The tensile test reveals that there is no obvious difference between tensile properties of TiN-coated specimens prepared with different substrate bias and the Zr-4 alloy specimen. And the weight gains of high temperature oxidation of TiN-coated specimens with different substrate bias are almost the same and are lower than uncoated Zr-4 alloy specimen. The XRD and EDS results show that TiN coating is oxidized and cracked and the internal Zr-4 substrate is also oxidized when the specimen is exposed to high temperature circumstance for a long time. (C) 2019 Elsevier B.V. All rights reserved.
作者机构：
School of mechanical engineering, University of South China , Hunan, China;[Peng Cong; Zhang Jiayu] Hunan Provincial Key Laboratory of Emergency Safety Technology and Equipment for Nuclear Facilities, University of South China , Hunan, China;[Rubina Bahar] International Islamic University Malaysia , Malaysia;[Tang Dewen] School of mechanical engineering, University of South China , Hunan, China ;[Tang Dewen] Hunan Provincial Key Laboratory of Emergency Safety Technology and Equipment for Nuclear Facilities, University of South China , Hunan, China
通讯机构：
[Tang Dewen] S;School of mechanical engineering, University of South China , Hunan, China;Hunan Provincial Key Laboratory of Emergency Safety Technology and Equipment for Nuclear Facilities, University of South China , Hunan, China
摘要：
Abstract High precision parts have been widely used in automobile, aerospace, medical and other fields. Conventional machining methods are difficult to meet the requirements of the high-quality requirements of components, including shape precision, dimensional accuracy, surface finish and surface integrity. Using milling instead of grinding can significantly improve machining efficiency of ultra-precision parts for difficult cut materials, especially high hardness SKD11 hardened steel. To improve the surface quality and the processing surface integrity of the parts, high-speed milling (HSM) can be able to meet the high-quality requirements of components. However, the quality of finish HSM is difficult to control through experiments. Therefore, the modified flow stress model of SKD11 hardened steel based on SHPB experimental is adopted to simulate the high-speed finish milling in this paper. The effect of cutting parameters on chip formation, cutting temperature, stress and cutting force of SKD11 are analyzed. Compared with the experimental data of cutting force of different cutting parameters, the simulation results are the same as the measured data. The results show that the model can predict the performance of the SKD11 high-speed finish milling process accurately.
通讯机构：
[Xiao, Weiwei] U;[Deng, Hua] C;Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;CNNC Jianzhong Nucl Fuel Co, Yibin 644000, Sichuan, Peoples R China.
关键词：
Accident-tolerant fuel;Adhesion strength;Roughness of substrate;Sputtered TiN coating;Sputtering power
摘要：
TiN coatings have been deposited on Zr-4 substrates using direct current (DC) magnetron sputtering and the effects of roughness of substrate and sputtering power on the microstructure, thickness/deposition rate, adhesion properties and residual stress of coatings have been studied. The microstructures of the coatings were characterized by using scanning electron microscope (SEM) and X-ray diffractometer (XRD). The thicknesses of the coatings were detected by using SEM. The adhesion property was tested by using scratch testing. The residual stress was measured by using the XRD method. The results shown that the microstructure, thickness/deposition rate, adhesion properties and residual stress of coating are significantly influenced by the roughness of substrate and sputtering power. The roughness of substrate has significant influence on the surface micrograph of the coating but not obvious on the thickness/deposition rate. The microstructure, thickness/deposition rate is remarkably affected by the sputtering power. In addition, the adhesion property does not vary monotonically with the roughness of substrate and the sputtering power. The adhesion strength presents a trend of first rises and then declines with the increase of surface roughness of substrate and sputtering power. The residual stresses of the coating were compressive and the residual stress magnitude of the coatings deposited by relatively low sputtering power was higher than that deposited by relatively high sputtering power. (C) 2018 Elsevier B.V. All rights reserved.
