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Surface Phenomena
Published in Pramod K. Naik, Vacuum, 2018
Ion beam implantation is a process in which accelerated ions are injected into the solid. This method can be employed to cause changes of the physical, chemical, electrical or optical properties of the solid. Ion beam implantation can cause change of crystalline structure of the solid. In 1906, Rutherford conducted the first ion implantation when he bombarded aluminum foil with alpha particles. For penetration of the order of 1 µm, accelerators of 40 kev to 400 keV are required. Such implanters are suitable for metal targets. Lindhard et al 71 proposed their approach explaining the range of low-energy heavy ions penetrating into solids. It was based on Thomas–Fermi atoms. Later, numerical methods were applied to traditional theoretical approaches 72,73 . The theory was based on statistical models of atom–atom collisions. Channeling occurs when the ion velocity is parallel to a major crystal orientation. when some ions may travel considerable distances with little energy loss. Once in a channel, the ion will continue in that direction, making many glancing internal collisions that are nearly elastic (their
BiCMOS Process Simulations
Published in Chinmay K. Maiti, Introducing Technology Computer-Aided Design (TCAD), 2017
In ion implantation, ions collide elastically with target atoms, creating ion deflections, energy loss, and displaced target atoms (recoils). Channeling is caused by ions traveling with few collisions and little drag along certain crystal directions. Ions come to rest after losing all the energy on elastic collisions (nuclear stopping) and inelastic drag (electronic stopping). Modeling of ion implantation needs to include the following: Ion energy loss mechanismsIon range distributionIon channeling in crystalline siliconImplantation-induced damage modeling
Laser powder bed fusion for AI assisted digital metal components
Published in Virtual and Physical Prototyping, 2022
Eunhyeok Seo, Hyokyung Sung, Hongryoung Jeon, Hayeol Kim, Taekyeong Kim, Sangeun Park, Min Sik Lee, Seung Ki Moon, Jung Gi Kim, Hayoung Chung, Seong-Kyum Choi, Ji-Hun Yu, Kyung Tae Kim, Seong Jin Park, Namhun Kim, Im Doo Jung
To investigate the microstructure of the metal bracket, electron backscatter diffraction (EBSD) and electron channelling contrast imaging (ECCI) analyses were conducted using a field-emission scanning electron microscope (JEOL, JSM-7610F). The EBSD was operated at 20 kV acceleration voltage, 20 mm working distance and 0.25 μm step size. Kikuchi diffraction patterns were imaged by a EBSD detector (Oxford Instruments Symmetry®) and processed by the Oxford Instruments AZtec 2.0 EBSD software. To maximise the backscattered electron intensity, a tilted 70-degree angle was set between the specimen surface and the normal incidence of the electron beam. The acquired data were analysed with the TSL OIMTM software. ECC images were obtained by backscattered electron (BSE) Detector. ECCI observations were performed at 30 kV acceleration voltage, 2 nA probe current and 15 mm working distance.
Enhanced corrosion resistance and wear resistance of duplex stainless steel processed by shot-peening combined with electrochemical nitriding
Published in Surface Engineering, 2021
Wei Wu, Gengzhe Shen, Liuyan Zhang, Junwei Mai, Shi Liu, Zhiwei Gu, Guibin Tan, Xiaohua Jie
Appropriate pretreatment of stainless steel before electrochemical nitriding can improve the comprehensive properties of nitriding layers. Tandon et al. [12] found that the cold working pretreatment of stainless steel improves the corrosion resistance of the electrochemical nitriding layer on its surface. Lv et al. [13] reported that the cryogenic cold rolling and electrochemical nitriding improve the corrosion resistance of 316L stainless steel. Thus, the microstructure of stainless steel can significantly affect the electrochemical nitriding process. Nitriding nanocrystalline stainless steel pretreated through cryogenic cold rolling exhibits improved corrosion resistance [13]. The surface nanocrystallization (SNC) of metals can be achieved through several methods, such as, surface mechanical attrition treatment [14], supersonic fine particle bombarding [15] and high-energy shot-peening (HESP) [16]. SNC promotes plasma nitriding, increases the depth of the nitriding layer and reduces nitriding temperature because ‘channelling tunnels’ for nitrogen are increased by crystal defects, including grain boundaries and dislocations [17–20]. Thus, SNC pretreatment of stainless steel benefits electrochemical nitriding.
Effects of pulsed laser surface treatments on microstructural characteristics and hardness of CrCoNi medium-entropy alloy
Published in Philosophical Magazine, 2019
Linjiang Chai, Kang Xiang, Jiying Xia, Vahid Fallah, Korukonda L. Murty, Zhongwen Yao, Bin Gan
Cross-sectional microstructural characteristics of the PLSTed specimens were investigated using electron channelling contrast (ECC) imaging and electron backscatter diffraction (EBSD) techniques in a Zeiss Sigma HD FEGSEM. The EBSD system consisted of a NordlysMax2 detector (Oxford Instruments), with AZtec 2.4 and HKL Channel 5 software packages used for information acquisition and post-processing analyses, respectively. Also, energy disperse spectroscopy (EDS) was used for analysing local compositions of the specimens. The above microstructural characterisations were mainly made for the RD-ND surfaces (normal to the travel direction of the laser beams) of the PLSTed specimens. Hardnesses of the laser-modified zones were measured in the RD-TD surfaces by use of a Vickers indentation tester (HVS-1000) at a load of 100 g for 10 s. For each specimen, more than twelve indentations were made along each measuring path at an interval of 200 μm and such measurements were repeated at least six times. Prior to such characterisations and measurements, the specimens were mechanically ground by silicon carbide abrasive paper to 3000# in the final step and then electro-polished in a mixed solution of 90 mL methanol and 10 mL perchloric acid at −20 °C and 30 V for 40 s.