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Application of shortened heat treatment cycles on A356 automotive brake calipers with respective globular and dendritic microstructures

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Transactions of Nonferrous metals Society of China 2010年第9期20卷 1780-1785页

作者： H.mLLER G.GOVEN DER W.E.STUmPF materials Science and manufacturing Council for Scientific and Industrial Research (CSIR) Department of materials Science and metallurgic al Engineering University of Pretoria

Since the automotive industry has many possible applications for semi-solid metal (SSm)-high-pressure die casting (HPDC) parts, the newly developed heat treatment cycles, as well as the traditional heat treatment cycles, were applied to A356 brake calipers cast using a LK DCC630 HPDC *** hardness measurements at a cross section of the brake calipers were performed, indicating that similar values can be obtained when using the significantly shorter heat treatment ***, the typical tensile properties that can be obtained for SSm-HPDC A356 brake calipers are compared with those manufactured by gravity die *** indicate that the differences in microstructures (globular or dendritic) do not have a noteworthy effect on the heat treatment *** implies that the short heat treatment cycles originally developed for globular SSm-HPDC A356 castings can be successfully applied to dendritic liquid A356 castings too.

关键词： semi-solid metal (SSm) forming heat treatment A356 brake caliper gravity die casting automotive

Fabrication and characterization of Ti6A14V/TiB2-TiC composites by powder metallurgy method

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Rare metals 2017年第10期36卷 806-811页

作者： m. Anandajothi S. Ramanathan V. Ananthi P. Narayanasamy Department of manufacturing Engineering Annamalai University Chidambaram Tamil Nadu 608 002 India Physics Section Faculty of Engineering and Technology Annamalai University Chidambaram Tamil Nadu 608 002 India Department of mechanical Engineering Kamaraj College of Engineering and Technology Virudhunagar Tamil Nadu 626 001 India

Titanium matrix （Ti6Al4V） composites rein- forced with TiB2 and TiC were produced through powder metallurgy method. The effect of addition of both TiB2 and TiC with different contents （2.5 wt%, 5.0 wt% and 7.5 wt%） on the density, microstructure and hardness properties of titanium matrix was investigated. The size distributions of the matrix alloy and reinforcement particles were measured by particle size analyzer. microhardness of the sintered composites was evaluated using vickers＇s hardness tester with a normal load of 3 N and a dwell time of 10 s. Ti6Al4V alloy and Ti6Al4V/TiB2-TiC composites were characterized through X-ray diffraction （XRD） and field emission scanning electron microscope （FESEm） equipped with energy-dispersive spectrometer （EDS）. The addition of TiB2 and TiC particles enriches the properties of Ti6Al4V alloy. The sintered Ti6Al4V/TiB2-TiC composite features a dense and pore-free microstructure with varying TiB2 and TiC particle distribution in the metal matrix. The results of this study show that the development of new phases plays a significant role in the properties of these composite materials.

关键词： Ti6Al4V TiB2 TiC microstructure

Amorphous-crystalline transition layers formation during quenching of Fe_(61)Co_7Zr_(10)mo_5W_2B_(15) melt

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中国有色金属学会会刊：英文版 2003年第1期13卷 10-13页

作者：高玉来孙剑飞沈军王刚 m I Petrzhik 周彼德 School of materials Science and Engineering Harbin Institute of Technology Harbin 150001 China A.A. Baikov Institute of metallurgy and materials Science Russian Academy of Sciences Moscow 117911 Russia

New Fe-based multicomponent amorphous alloys have been developed recently based on empirical rules for large glass forming ability(GFA). In the present investigation, the master alloy ingot with the nominal composition of Fe 61Co 7Zr 10mo 5W 2B 15(mole fraction, %) was prepared by arc-melting under Ti-gettered Ar atmosphere. The Fe-based buttons with different transverse cross sections were fabricated by arc-melting method, and the d 2.5 mm Fe-based rods were manufactured by injection technique. Characterization of the ingots and the parameters associated with the thermal stability were carried out by X-ray diffractometry(XRD) and high temperature differential scanning calorimeter(DSC), respectively. The interval of the supercooled liquid region is 39 K for the Fe-based alloy. The GFA of Fe-based alloys is relatively lower, to the buttons obtained are all crystallized. The Fe-based rod exhibites a high vickers hardness up to HV 1 329. In addition, an amorphous-crystalline transition layers are observed in the rod. This transition zone is caused by unhomogeneous temperature distribution and relatively lower GFA for Fe-based alloys.

关键词：铁基合金玻璃态合金金属玻璃玻璃成形性能淬火结晶化

microstructure Evolution during Friction Stir Welding of Aluminum Alloy AA2219

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Journal of materials Science & Technology 2010年第8期26卷 747-753页

作者： K.S.Arora S.Pandey m.Schaper R.Kumar mechanical Engineering Department Indian Institute of Technology Institut fuer Werkstoffwissenschaft Technische Universitaet Dresden Institut fuer Sicherheitsforschung Forschungszentrum Dresden-Rossendorf Engineering Division National Metallurgical Laboratory

The characterization of microstructure evolution in friction stir welded aluminum alloy was carried out by optical microscopy （Om） and transmission electron microscopy （TEm） and electron backscatter diffraction （EBSD）. The weld nugget consisted of very fine equiaxed grains and experienced dissolution of nearly half of metastable precipitates into the matrix during welding. Thermomechanically affected zone （TmAZ） also experienced dissolution of precipitates but to a lesser extent whereas coarsening of precipitates was observed in heat affected zone （HAZ）. Grain boundary misorientation measurements using EBSD indicated continuous dynamic recrystallization as the underlying mechanism for the fine equiaxed nugget grains. The yield and tensile strength of the weld decreased with comparison to base material. But due to the decrease of grain size and the dissolution of second phase precipitates, an increased Charpy energy value was observed in the weld n u gget.

关键词： Friction stir welding AA2219 Precipitates vickers hardness Tensile testing Charpy impact energy

婴幼儿、儿童和青少年终末期医疗照护：NICE指南概要

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英国医学杂志中文版 2017年第11期20卷 629-632页

作者： Gemma Villanueva m Stephen murphy David vickers Emily Harrop Katharina Dworzynski 孙婧束永前 National Guideline Alliance Royal College of Gynaecologists and ObstetriciansLondon NW1 4RGUK Cambridgeshire Community Services NHS Trust St Ives PE27 4LG UK East Anglia'sChildren's Hospices Milton CB24 6DF UK Helen & DouglasHouse Oxford OX41RW UK Oxford UniversityHospitals OxfordOX3 9DU UK 江苏省肿瘤医院肿瘤科

儿童和青少年会有多种临终状态，有时可能许多年生活在这种状态下。本指南建议，终末期医疗照护（又称为临终关怀或姑息治疗）应作为一个长期行动，在被诊断为已无多日时开始，并为未来规划。有时可能要在孩子出生前就开始规划。

关键词：婴幼儿儿童医疗照护发展现状

Load dependent microstructural evolution in an as-cast 26%Cr high chromium cast iron during unlubricated sliding

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Friction 2022年第8期10卷 1258-1275页

作者： U.Pranav NAYAK Sebastian SUÁREZ Valentin PESNEL Frank mÜCKLICH maría Agustina GUITAR Department of materials Science Saarland UniversitySaarbrücken 66123Germany materials Engineering Center Saarland Saarbrücken 66123Germany Ecole Européenne d’ingénieurs en Génie des matériaux Universitéde LorraineNancy 54000France

In the current study,an as-cast 26%Cr high chromium cast iron(HCCI)alloy was subjected to dry-sliding linear wear tests,under different *** loads were selected based on analytically computing the critical load(PC)i.e.,the load necessary to induce plastic *** PC was calculated to be 15 N and accordingly,a sub-critical load(5 N)and an over-critical load(20 N)were *** influence of increasing the load during the wear test was investigated in terms of the matrix microstructural behaviour and its ability to support the surrounding *** morphological aspects of the wear tracks,and the deformed matrix microstructure adjacent and underneath the track was analysed by confocal laser scanning microscope(CLSm)and scanning electron microscope(SEm),*** evidence of plastic deformation of the matrix was observed below *** the contrary,at loads equal to and higher than PC,the austenitic matrix plastically deformed as evidenced by the presence of slip *** backscattered diffraction(EBSD)measurements in terms of grain reference orientation deviation,and micro-vickers hardness of the austenitic matrix indicated a deformation depth of about 40μm at the maximum applied load of 20 *** active wear mechanisms during sliding were a combination of both adhesive and abrasive wear,although increasing the load shifted the dominant mechanism towards *** was primarily attributable to the increased propensity for carbide cracking and fracturing,combined with the inability of the hardened austenitic matrix surface and sub-surface to adequately support the broken carbide ***,the shift in the dominant wear mechanism was also reflected in the wear volume and subsequently,the wear rate.

关键词： high chromium cast iron unlubricated sliding plastic deformation wear resistance carbide spallation matrix hardness

Ni/Al Intermetallics Plasma Transferred Arc Processing

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材料热处理学报 2004年第5B期25卷 948-951页

作者： Veronica A. B. Almeida Ana Sofia C. m. D'Oliveira master student - PIPE Federal University of Parana Curitiba/BrazilMechanical Engineering Department Federal University of Parana Curitiba/Brazil

In-situ alloy development during surface processing allows for a limitless materials selection to protect components exposed to severe service conditions. In fact surface alloying offers the possibility to strengthen surface components with alloys that would not be possible to process otherwise. This work used Plasma transferred arc (PTA) hardfacing for surface alloying. Different amounts of aluminium powder, 5-25%, were added to a Ni based superalloy, from Hastealloy C family, in the atomized form. The mixture was homogeneized in a ball mill and PTA deposited on carbon steel substrate. The influence of different processing parameters on the final surface alloy was evaluated as current intensity and depositing velocity were varied. Coatings were characterized by optical and scanning electronic microscopy, X-ray diffraction and vickers microhardness profiles, under a 500g load. Results showed that PTA hardfacing is an adequate surface alloying. For the conditions tested increasing hardness was obtained by solid solution for the lower amounts of Al added and due to the new intermetallic phases for the richer Al mixture.

关键词： PTA合金等离子转移电弧 Ni/Al金属互化物表面处理

Dynamic compressive behaviour of Ti-6Al-4V alloy processed by electron beam melting under high strain rate loading

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Advances in manufacturing 2015年第3期3卷 232-243页

作者： A.mohammadhosseini S.H.masood D.Fraser m.Jahedi Department of mechanical and Product Design Engineering Faculty of ScienceEngineering and TechnologySwinburne University of Technology Commonwealth Scientific and Industrial Research Organisation

This paper documents an investigation into the compressive deformation behaviour of electron beam melting （EBm） processing titanium alloy （Ti-6A1-4V） parts under high strain loading conditions. The dynamic compression tests were carried out at a high strain rate of over 1 × 10^3/S using the split Hopkinson pressure bar （SHPB） test system and for comparison the quasi-static tests were performed at a low strain rate of 1×10^-3/s using a numerically controlled hydraulic materials test system （mTS） testing machine at an ambient temperature. Furthermore, microstructure analysis was carried out to study the failure mechanisms on the deformed samples. The vickers micro-hardness values of the samples were measured before and after the compression tests. The microstructures of the compressed samples were also characterized using optical microscopy. The particle size distribution and chemical composition of powder material, which might affect the mechanical properties of the specimens, were investigated. In addition, the numerical simulation using commercial explicit finite element software was employed to verify the experimental results from SHPB test system.

关键词： Additive manufacturing Electron beam melting (EBm) Titanium alloys Split Hopkinson

Effect of Co content on electrodeposition mechanism and mechanical properties of electrodeposited Ni-Co alloy

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Transactions of Nonferrous metals Society of China 2016年第2期26卷 484-491页

作者： m.ZAmANI A.AmADEH S.m.LARI BAGHAL School of metallurgy and materials Engineering College of EngineeringUniversity of Tehran Department of materials Science and Engineering Faculty of EngineeringShahid Chamran University

Ni–Co coatings with various cobalt contents were electrodeposited from modified Watts bath. The effect of cobalt content on electrodeposition mechanism of the coatings was studied by electro-chemical impedance spectroscopy method （EIS）. Surface morphology and crystallographic structure of the coatings were investigated by means of SEm and XRD. mechanical properties of the coatings were determined using vickers microhardness and tensile tests. It was found that with increasing the Co2＋ions in electroplating bath, the charge transfer resistance （Rct）of Ni-Co film increased whereas the Warburg impedence decreased. This may be due to enhancement in coverage of cathode surface by Co（OH）2 and higher diffusion rate of metal ions towards cathode surface, respectively. Also, with increasing the cobalt content in the bath, cobalt content in the alloy coating increased anomalously and （111） texture consolidated gradually. With increasing the cobalt content up to 45% in alloy coating, the grain size decreased and consequently, hardness and strength of the alloy increased. Further enhancement of cobalt content up to 55% led to a little decrease in hardness and strength. The maximum ductility was observed for Ni-25%Co coating due to relatively small grain size and compact structure.

关键词： Ni-Co coating electrodeposition microstructure mechanical properties