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Microstructure refinement and work hardening in a machined surface layer induced by turning Inconel 718 super alloy

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International Journal of Minerals,Metallurgy and Materials 2018年第8期25卷 937-949页

作者： Xiao-ping ren Zhan-qiang Liu School of Mechanical Engineering Shandong University Key Laboratory of High Efficiency and Clean Mechanical Manufacture Ministry of EducationShandong University

The microstructural changes in the machined surface layer of Ni-based super alloys essentially determine the final performance of the structural components of aerospace engines in which these alloys are *** this work,multiscale metallurgical observations using scanning electron microscopy,electron-backscatter diffraction microscopy,and transmission electron microscopy were conducted to quantitatively characterize the microstructure of the machined ***,to elucidate the factors that affect the formation of the refinement microstructure,the distributions of the deformation parameters(strain,strain rate,and temperature) in the machined subsurface were analyzed.A dislocation–twin interaction dynamic recrystallization mechanism for grain refinement during machining of Inconel 718 is ***,microhardness evolution induced by grain refinement in the machined surface is *** results suggest that the gradient microstructure and the work hardening can be optimized by controlling the cutting parameters during turning of Inconel 718.

关键词： grain refinement dislocation–twin interaction work hardening turning Inconel 718

Coupled effect of climate change and human activities on the restoration/degradation of the Qinghai-Tibet Plateau grassland

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Journal of Geographical Sciences 2021年第9期31卷 1299-1327页

作者： YUAN Qin YUAN Quanzhi ren ping Institute of Geography and Resources Science Sichuan Normal UniversityChengdu 610101China Sustainable Development Research Center of Resources and Environment of Western Sichuan Sichuan Normal UniversityChengdu 610066China Key Laboratory of Land Resources Evaluation and Monitoring in Southwest Ministry of EducationSichuan Normal UniversityChengdu 610066China

Climate change(CC)and human activities(HA)are the main reasons for the restoration/degradation of the Qinghai-Tibet Plateau(QTP)*** related studies have been conducted thus far,but the impact mechanism of CC coupled with HA on QTP remains *** summarized the two main coupling factors in recent years(specifically,in the past five years)and obtained the following conclusions.(1)CC and HA have positive and negative effects on the QTP grassland *** primarily affects grassland ecology through temperature,humidification,and extreme climate,and HA mainly affects ecosystems through primary,secondary,and tertiary industries and restoration measures.(2)CC coupled with HA affects soil,plants,animals,and fungi/*** makes the snow line rise by increasing the temperature,which expands the zone for *** also restricts HA through hydrological changes,extreme climate,and outbreak of pikas and ***,measures are implemented through HA to control and adapt to ***,the grassland ecosystem is comprehensively influenced by CC and HA.(3)The grassland ecosystem dynamically adapts to the disturbance caused by CC and HA by changing its physiological characteristics,distribution range,diet structure,community structure,and physical ***,it responds to environmental changes through desertification,poisonous weeds,rodent outbreak,release of harmful gases,and other *** work can be used as a reference for the sustainable development of the QTP grassland.

关键词： Qinghai-Tibet Plateau geochemistry soil organic carbon net primary productivity pikas pests Cordyceps sinensis

Boosting multi-features with prior knowledge for mini unmanned helicopter landmark detection

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第2期9卷 256-261页

作者： Qin-yuan ren ping LI Bo HAN The State Key Laboratory of Industrial Control Technology Zhejiang University Hangzhou 310027 China

Without sufficient real training data,the data driven classification algorithms based on boosting method cannot solely be utilized to applications such as the mini unmanned helicopter landmark image *** this paper,we propose an approach which uses a boosting algorithm with the prior knowledge for the mini unmanned helicopter landmark image *** stage forward stagewise additive model of boosting is analyzed,and the approach how to combine it with the prior knowledge model is *** approach is then applied to landmark image detection,where the multi-features are boosted to solve a series of problems,such as rotation,noises affected,*** of real flight experiments demonstrate that for small training examples the boosted learning system using prior knowledge is dramatically better than the one driven by data only.

关键词： Boosting Prior knowledge model Landmark detection

Dual-mode predictive control of a rotor suspension system

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Science China(Information Sciences) 2020年第1期63卷 178-189页

作者： Yue WU Gui-ping ren Hai-Tao ZHANG Key Laboratory of Image Processing and Intelligent Control School of Artificial Intelligence and AutomationHuazhong University of Science and Technology State Key Laboratory of Digital Manufacturing Equipments and Technology

Rotor active magnetic bearing(rotor-AMB) systems are frequently used to alleviate vibrations for various applications such as in national defense, manufacturing industries, IC production, and aerospace engineering. One obstacle to improve machining efficiency and quality is the open-loop instability of rotorAMB systems during the machining process. We built a closed-loop processing platform using a spindle rotor installed with AMBs and thereby developed a rotor-AMB suspension system embedded with a dual-mode predictive controller(DMPC). The performance of the system is thus substantially improved. In the proposed DMPC, both model-based prediction and receding horizon optimization are utilized to guarantee the closedloop stability of the rotor-AMB suspension systems with input constraints. Finally, the effectiveness and superiority of the proposed method are examined through substantial levitation experiments on a machining platform with installed AMBs.

关键词： dual-mode predictive control system identification optimization control model predictive control suspension control

Researches on the Structure and Properties of Mullite Solid Solution Made from Industrial Waste

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Chinese Journal of Structural Chemistry 2006年第8期25卷 965-970页

作者： RUAN Yu-Zhong YU Yan WU ren-ping College of Materials Science and Engineering Fuzhou University Fuzhou 350002 China

The waste slag from aluminum profile factory and silicon fine powder from ferroalloy factory were utilized as the main raw materials to synthesize mullite solid solution Al4＋2xSi2-xO10-x/2, whose defect formation mechanism, crystalline phase composition, crystal cell parameters, microstructures and morphologies were characterized in detail by XRD and SEM. The results show that because of the ultrafine particle size of the materials, the content of mullite solid solution synthesized by this method is higher than that by regular method. Keywords： waste slag from aluminum factory, silicon fine powder, mullite, solid solution

关键词： waste slag from aluminum factory silicon fine powder mullite solid solution

Studies on the Structure and Properties of Multiphase Al_2O_3 Abrasion-resistant Ceramics

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Chinese Journal of Structural Chemistry 2006年第7期25卷 805-810页

作者： WU ren-ping YU Yan RUAN Yu-Zhong College of Materials Science and Engineering Fuzhou University Fuzhou 350002 China

The Al2O3 abrasion-resistant ceramics is successfully prepared by using waste aluminum sludge as the main raw material with the addition of a little clay, talc and barium carbonate. The crystal structure and microstructure of ceramic are characterized by means of XRD, SEM, etc., and the physical and mechanical properties are also tested. The results show that besides the phase of corundum, a little mullite, Mg-Al spinel and hyalophane phases also exist in the product. These phases are produced via reaction in-situ, which can inhibit the overgrowth of Al2O3 grain in grain boundary, and improve the integral property of the material.

关键词： Al2O3 ceramic crystal structure property in-situ synthesis

Phase stability of Fe_(23)Zr_(6)and thermodynamic reassessment of Fe-Zr system

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Journal of Iron and Steel Research International 2021年第11期28卷 1375-1389页

作者： Ze-ting Du Lei Zou Cui-ping Guo Xue-ping ren Chang-rong Li Department of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Northwest Institute for Nonferrous Metal Research Xi’an 710016ShaanxiChina

The stability of the Fe_(23)Zr_(6)phase in Fe–Zr system was studied,and the partial Fe–Zr phase diagram was revised by means of X-ray diffraction,electron probe microanalysis and differential thermal analysis *** the basis of the experimental results in the present work and literature,the Fe–Zr system was reassessed using CALculation of PHAse Diagram(CALPHAD)*** phases,liquid,fcc,bcc and hcp,are modeled as the substitutional *** intermetallic compounds,hex.-Fe_(2)Zr,Fe_(2)Zr,FeZr_(2)and FeZr3 phases,are treated as Fe_(2)(Fe,Zr)1,(Fe,Zr)2(Fe,Zr)1,(Fe,Zr)1Zr_(2)and(Fe,Zr)1(Fe,Zr)3 by a two-sublattice model,*** Fe_(23)Zr_(6)phase is treated as stoichiometric compound.A set of self-consistent thermodynamic parameters of the Fe–Zr system was *** results confirm the stability of Fe_(23)Zr_(6)phase,improve the phase diagram of the Fe–Zr system and provide a theoretical reference for the development of Zr alloys.

关键词： Fe_(23)Zr_(6) Fe–Zr system Thermodynamic parameter CALPHAD method

Degradation Characters of La-Mg-Ni-Based Metal Hydride Alloys:Corrosion and Pulverization Behaviors

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Acta Metallurgica Sinica(English Letters) 2018年第7期31卷 723-734页

作者： Yi-Ming Li Yang-Huan Zhang Hui-ping ren Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources Inner Mongolia University of Science and Technology

Degradation behaviors of three typical La-Mg-Ni alloys, La2MgNi9, La1.5Mg0.5Ni7 and La4MgNi19, were studied. La1.5- Mg0.5Ni7 with （La,Mg）2Ni7 as main phase presents better discharge capacity and cycling stability. The three alloys suffer severe pulverization and corrosion after electrochemical cycles, which are considered to be the significant factor attributing to the capacity deterioration. However, the overall corrosion extent of the three cycled alloys aggravates successively, which is inconsistent with the result that LaEMgNi9 presented poor cycling stability and also the assumption that alloy with high Mg content is easy to be corroded. The intrinsic anti-corrosion and anti-pulverization characteristics of the three alloys are mainly focused in this work. Immersion corrosion experiments demonstrate that the Mg-rich phases are more easily to be corroded. The corrosion resistance of the three alloys presents an improved trend which is inversely proportional to abundance of the Mg-rich phases. However, the anti-pulverization abilities present an inverse trend, which is closely related to the mechanical property of various phase structures. LaNi5 with the highest hardness is easy to crack, but the soft （La,Mg）Ni2 is more resistant to crack formation and spreading. Thus, the weaker corrosion of La2MgNi9 after electro- chemical cycling is attributed to the better intrinsic anti-pulverization capability though the anti-corrosion is poor. As La4MgNi19 possesses excellent corrosion resistance, enhancement of the anti-pulverization ability is urgent for improvement in the cycling stability.

关键词： La-Mg-Ni-based alloys Degradation behaviors Corrosion Pulverization

Efect of high temperature and high strain rate on the dynamic mechanical properties of Fe-30Mn-3Si-4Al TWIP steel

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International Journal of Minerals,Metallurgy and Materials 2013年第9期20卷 835-841页

作者： Zhi-ping Xiong Xue-ping ren Wei-ping Bao Jian Shu Shu-xia Li Hai-tao Qu School of Materials Science and Engineering University of Science and Technology Beijing School of Mechanical Materials and Mechatronic Engineering University of Wollongong School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

The dynamic mechanical properties of Fe-30Mn-3Si-4A1 twinning induced plasticity （TWIP） steel were studied by the split-Hopkinson pressure bar （SHPB） at temperatures of 298-1073 K and strain rates of 700, 2500, and 5000 s-1. The TWIP steel indicates strain rate hardening effect between 700 and 2500 s-1, but it shows strain rate softening effect between 2500 and 5000 s-1. In addition, the strain rate softening effect enhances with an increase in deformation temperature. After deformation, the microstructures were studied by optical microscopy （OM）. It is shown that the deformation bands become more convergence, a part of which become interwoven with an increase in strain rate, and the dynamic recovery and recrystallization are enhanced with an increase in both temperature and strain rate.

关键词： TWIP steels mechanical properties strain rate temperature