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Application of novel constrained friction processing method to produce fine grained biomedical Mg-Zn-Ca alloy

Journal of Magnesium and Alloys 2024年第2期12卷 516-529页

作者： Ting Chen Banglong Fu Junjun Shen Uceu F.H.R.Suhuddin björn wiese Yuanding Huang Min Wang Jorge F.dos Santos Jean Pierre Bergmann Benjamin Klusemann Solid State Materials Processing Institute of Material MechanicsHelmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany Functional Magnesium Materials Institute of Metallic BiomaterialsHelmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany Shanghai Key Laboratory of Materials Laser Processing and Modification Shanghai Jiao Tong UniversityDongchuan Road 800Shanghai 200240China Applied Materials and Manufacturing Energy and Environment DivisionPacific Northwest National LaboratoryPO Box 999RichlandWA 99352USA Production Technology Group Technisiche Universität IlmenauGustav-Kirchhoff-Platz 2Ilmenau 98693Germany Institute for Production Technology and Systems Leuphana University of LüneburgUniversitätsallee 1Lüneburg 21335Germany

In order to obtain Mg alloys with fine microstructures and high mechanical performances,a novel friction-based processing method,name as“constrained friction processing(CFP)”,was investigated.Via CFP,defect-free Mg-Zn-Ca rods with greatly refined grains and high mechanical properties were produced.Compared to the previous as-cast microstructure,the grain size was reduced from more than 1 mm to around 4μm within 3 s by a single process cycle.The compressive yield strength was increased by 350%while the ultimate compressive strength by 53%.According to the established material flow behaviors by“tracer material”,the plastic material was transported by shear deformation.From the base material to the rod,the material experienced three stages,i.***.deformation by the tool,upward flow with additional tilt,followed by upward transportation.The microstructural evolution was revealed by“stop-action”technique.The microstructural development at regions adjacent to the rod is mainly controlled by twinning,dynamic recrystallization(DRX)as well as particle stimulated nucleation,while that within the rod is related to DRX combined with grain growth.

关键词： Constrained friction processing Magnesium alloys Microstructure Mechanical properties Grain refinement Plastic deformation

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Pore characterization of PM Mg–0.6Ca alloy and its degradation behavior under physiological conditions

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Journal of Magnesium and Alloys 2021年第2期9卷 686-703页

作者： Eshwara Phani Shubhakar Nidadavolu Diana Krüger Berit Zeller-Plumhoff Domonkos Tolnai björn wiese Frank Feyerabend Thomas Ebel Regine Willumeit-Römer Division Metallic Biomaterials Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany Magnesium Innovation Center(MagIC) Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany

Several material parameters affect degradation characteristics of Mg and its alloys under physiological conditions.Porous Mg materials are interesting for their simultaneous degradation and drug delivery capabilities.However,an increase in pore surface area is detrimental to both degradation resistance and subsequent mechanical properties.The present work aims at determining the threshold porosity value in Mg–0.6 Ca specimens produced by powder metallurgy(PM)below which low degradation rates persist with acceptable mechanical properties.Seven different porous Mg–0.6 Ca specimens containing both closed and open pore structures were fabricated with porosities ranging from 3%to 21%.Degradation profiles were obtained via a semi static immersion test over 16 days under physiological conditions using Dulbecco’s modified Eagle’s medium with Glutamax and 10%fetal bovine serum as supplements.The results are related to morphological pore parameters like pore size distribution,pore interconnectivity and pore curvatures that were quantified using an ex situμCT analysis.In general,with decreasing porosity a decrease in pore interconnectivity is seen followed by rounding of the pores.Low degradation rates(MDR<0.3 mm/year)are observed in specimens until 10%porosity,however,the upper bound for reproducible degradation is observed to be in specimens until 12%porosity.This porosity level also marks the transition from closed to open pore nature with a simultaneous change in pore interconnectivity from less than 10%to greater than 95%,below and above this porosity level,respectively.The tensile strength and elongation to failure recorded for specimens with 10%porosity were 70 MPa and 2%,respectively displaying positive traits of both homogenous degradation and mechanical properties.The results suggest that high pore interconnectivity is the dominant factor controlling degradation and mechanical properties in porous Mg-0.6 Ca specimens.The results also indicate a good sintering response of Mg-0.6 Ca specimens providing further mater

关键词： Porous Mg-0.6Ca In vitro Degradation μCT Sintering

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Assessing the microstructure and in vitro degradation behavior of Mg-xGd screw implants using μCT

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Journal of Magnesium and Alloys 2021年第6期9卷 2208-2223页

作者： Diana Krüger Berit Zeller-Plumhoff björn wiese Sangbong Yi Marcus Zuber D.C.Florian Wieland Julian Moosmann Regine Willumeit-Römer Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany Institute of Material and Process Design Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany Institute for Photon Science and Synchrotron Radiation Karlsruhe Institute of TechnologyHerrmann-von-Helmholtz-Platz 1Eggenstein-Leopoldshafen 76344Germany Laboratory for Applications of Synchrotron Radiation Karlsruhe Institute of TechnologyKaiserstr.12KarlsruheGermany Institute of Materials Physics Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany

Biodegradable implants are taking an increasingly important role in the area of orthopedic implants with the aim to replace permanent implants for temporary bone healing applications.During the implant preparation process,the material’s surface and microstructure are being changed by stresses induced by machining.Hence degradable metal implants need to be fully characterized in terms of the influence of machining on the resulting microstructure and corrosion performance.In this study,micro-computed tomography(μCT)is used for the quantification of the degradation rate of biodegradable implants.To our best knowledge,for the first time quantitative measures are introduced to describe the degradation homogeneity in 3D.This information enables a prediction in terms of implant stability during the degradation in the body.Two magnesium gadolinium alloys,Mg-5Gd and Mg-10 Gd(all alloy compositions are given in weight%unless otherwise stated),in the shape of M2 headless screws have been investigated for their microstructure and their degradation performance up to 56 days.During the microstructure investigations particular attention was paid to the localized deformation of the alloys,due to the machining process.In vitro immersion testing was performed to assess the degradation performance quantified by subsequent weight loss and volume loss(usingμCT)measurements.Although differences were observed in the degree of screw’s near surface microstructure being influenced from machining,the degradation rates of both materials appeared to be suitable for application in orthopedic implants.From the degradation homogeneity point of view no obvious contrast was detected between both alloys.However,the higher degradation depth ratios between the crests and roots of Mg-5Gd ratios may indicated a less homogeneous degradation of the screws of these alloys on contract to the ones made of Mg-10Gd alloys.Due to its lower degradation rates,its more homogeneous microstructure,its weaker texture and better degradation performance extruded Mg-1

关键词： Magnesium alloys Biodegradable implant Degradation rate Degradation homogeneity Micro-comptued tomography

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Alloying effect of silver in magnesium on the development of microstructure and mechanical properties by indirect extrusion

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Journal of Magnesium and Alloys 2021年第1期9卷 112-122页

作者： bjorn wiese Regine Willumeit-Römer Dietmar Letzig Jan Bohlen Division Metallic Biomaterials Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany Magnesium Innovation Center(MagIC) Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany

The effect of Ag in solid solution on the microstructure,texture and the deformation behaviour of indirectly extruded Mg was investigated.Ag as a solid solution strengthener affects the behaviour during extrusion,resulting in enhanced deformation related heating and corresponding coarser grained microstructures.No substantial effect on the texture development is revealed.The mechanical properties simultaneously increase in stress and strain levels with increasing Ag content,especially in tension as a result of the changing impact of the slip modes which can be associated with a decrease of the lattice parameters as well as the c/a ratio of the hcp lattice structure.In compression tests with twin dominated flow,the impact is much smaller on the compressive yield stress but higher with respect to the twinning related strain hardening rate.Solid solution strength functions for Fleischer and Labusch were determined,also confirming the anisotropic behaviour of the extruded Mg alloys.

关键词： Mg-Ag-alloys Lattice parameters Indirect extrusion Microstructure Mechanical properties

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Accelerated design of high-performance Mg-Mn-based magnesium alloys based on novel bayesian optimization

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Journal of Magnesium and Alloys 2024年第2期12卷 750-766页

作者： Xiaoxi Mi Lili Dai Xuerui Jing Jia She bjørn Holmedal Aitao Tang Fusheng Pan College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Southwest Technology and Engineering Research Institute Chongqing 400039China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China Department of Materials Science and Engineering Norwegian University of Science and Technology(NTNU)Trondheim 7051Norway

Magnesium(Mg),being the lightest structural metal,holds immense potential for widespread applications in various fields.The development of high-performance and cost-effective Mg alloys is crucial to further advancing their commercial utilization.With the rapid advancement of machine learning(ML)technology in recent years,the“data-driven''approach for alloy design has provided new perspectives and opportunities for enhancing the performance of Mg alloys.This paper introduces a novel regression-based Bayesian optimization active learning model(RBOALM)for the development of high-performance Mg-Mn-based wrought alloys.RBOALM employs active learning to automatically explore optimal alloy compositions and process parameters within predefined ranges,facilitating the discovery of superior alloy combinations.This model further integrates pre-established regression models as surrogate functions in Bayesian optimization,significantly enhancing the precision of the design process.Leveraging RBOALM,several new high-performance alloys have been successfully designed and prepared.Notably,after mechanical property testing of the designed alloys,the Mg-2.1Zn-2.0Mn-0.5Sn-0.1Ca alloy demonstrates exceptional mechanical properties,including an ultimate tensile strength of 406 MPa,a yield strength of 287 MPa,and a 23%fracture elongation.Furthermore,the Mg-2.7Mn-0.5Al-0.1Ca alloy exhibits an ultimate tensile strength of 211 MPa,coupled with a remarkable 41%fracture elongation.

关键词： Mg-Mn-based alloys High-performance Alloy design Machine learning Bayesian optimization

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Induction System for a Fusion Reactor: Quantum Mechanics Chained up

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Journal of High Energy Physics, Gravitation and Cosmology 2024年第1期10卷 158-166页

作者： Friedrich björn Grimm CEO of RES-Institute Stuttgart Germany

In the quest for a sustainable and abundant energy source, nuclear fusion technology stands as a beacon of hope. This study introduces a groundbreaking quantum mechanically effective induction system designed for magnetic plasma confinement within fusion reactors. The pursuit of clean energy, essential to combat climate change, hinges on the ability to harness nuclear fusion efficiently. Traditional approaches have faced challenges in plasma stability and energy efficiency. The novel induction system presented here not only addresses these issues but also transforms fusion reactors into integrated construction systems. This innovation promises compact fusion reactors, marking a significant step toward a clean and limitless energy future, free from the constraints of traditional power sources. This revolutionary quantum induction system redefines plasma confinement in fusion reactors, unlocking clean, compact, and efficient energy production.

关键词： Fusion Reactor Plasma Confinement Quantum Mechanics Clean Energy

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Deteriorated corrosion performance of micro-alloyed Mg-Zn alloy after heat treatment and mechanical processing

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Journal of Materials Science & Technology 2021年第33期92卷 214-224页

作者： Yiming Jin Carsten Blawert Hong Yang bjorn wiese Jan Bohlen Di Mei Min Deng Frank Feyerabend Regine Willumeit Division of Metallic Biomaterials Helmholtz-Zentrum Geesthacht21502 GeesthachtGermany Southwest Technology and Engineering Research Institute 400039 ChongqingChina Magnesium Innovation Center Helmholtz-Zentrum Geesthacht21502 GeesthachtGermany State Key Laboratory of Mechanical Transmissions College of Materials Science and EngineeringChongqing UniversityChongqing400044China National Engineering Research Center for Magnesium Alloys Chongqing University400044 ChongqingChina Faculty of Engineering Christian-Albrechts-Universität zu Kiel24143 KielGermany

The corrosion performances of the as-cast and solution-treated Mg-0.5Zn samples were investigated in 0.9%Na Cl solution and compared.From the electrochemical measurement results and corrosion morphology observations,it is found that the corrosion resistance of Mg-0.5Zn deteriorated with the extension of solution treatment duration.The main reason was the formation of Fe-Si precipitates with higher Fe concentrations during heat treatment.The Fe-Si precipitates,especially the ones with high Fe contents influenced the corrosion initiation and propagation significantly.In regard of corrosion performance,the solution-treated and then extruded sample was also performing not as good as the cast and then directly extruded sample.

关键词： Magnesium Alloy Internetallics SEM Inclusions Corrosion

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What is required for better progress in clinical andscientific andrology involving sperm assessments?

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Asian Journal of Andrology 2024年第3期26卷 229-232页

作者： Lars björndahl ANOVA Karolinska University Hospital and Karolinska Institutet Norra Stationsgatan 69 Level 4 S-113 64 Stockholm Sweden.

In scientific publications based on basicsemen examination,there is a generallack of consistency and transparencyregarding laboratory techniques used.To support improvements in clinicaland scientific andrology,it is essential toincrease understanding of basic physiologyand biology,and enhance compliancewith existing recommendations andinternational standards.Study designsneed to be improved as well as transparencyof laboratory methods used and openpublication of data obtained.

关键词： transparency consistency clinical

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Conventional Geothermal Systems and Unconventional Geothermal Developments: An Overview

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Open Journal of Geology 2024年第2期14卷 196-246页

作者： Maryam Khodayar Sveinbjörn björnsson Consultant and Researcher in Geosciences Reykjavík Iceland Formerly at National Energy Authority of Iceland Reykjavík Iceland

This paper provides an overview of conventional geothermal systems and unconventional geothermal developments as a common reference is needed for discussions between energy professionals. Conventional geothermal systems have the heat, permeability and fluid, requiring only drilling down to °C, normal heat flow or decaying radiogenic granite as heat sources, and used in district heating. Medium-temperature (MT) 100°C - 190°C, and high-temperature (HT) 190°C - 374°C resources are mostly at plate boundaries, with volcanic intrusive heat source, used mostly for electricity generation. Single well capacities are °C - 500°C) and a range of depths (1 m to 20 Km), but lack permeability or fluid, thus requiring stimulations for heat extraction by conduction. HVAC is 1 - 2 m deep and shallow geothermal down to 500 m in wells, both capturing °C, with °C are either advanced by geothermal developers at rnatives are still experimental, overcoming costs and technological challenges to become fully commercial. Meanwhile, the conventional geothermal resources remain the most proven opportunities for investments and development.

关键词： Conventional Geothermal Systems Unconventional Geothermal Developments Shallow and Deep Closed-Loops Enhanced Geothermal Systems Supercritical and Millimeter-Wave Drilling

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揭示鱼鳞降低冰黏附力的奥秘

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Science China Materials 2024年第6期67卷 2016-2022页

作者：王锋刘思琪肖森波 bjørn Skallerud 张志良何健英 Department of Structural Engineering Norwegian University of Science and Technology(NTNU)Trondheim 7491Norway Suzhou Laboratory Suzhou 215000China

近几十年来,大量的研究文献表明,研究人员一直在探究静态表面特性(包括自由能、韧性和弹性)对疏冰性的影响.然而,对于动态表面特性在辅助除冰方面的理解非常有限.在本工作中,我们重点研究了北三文鱼表皮的冰黏附强度,并且观察到了有趣... 详细信息

近几十年来,大量的研究文献表明,研究人员一直在探究静态表面特性(包括自由能、韧性和弹性)对疏冰性的影响.然而,对于动态表面特性在辅助除冰方面的理解非常有限.在本工作中,我们重点研究了北三文鱼表皮的冰黏附强度,并且观察到了有趣的各向异性的冰黏附行为.与顺着鱼鳞生长方向的冰黏附强度(353±95 kPa)相比,逆着鱼鳞生长方向的冰黏附强度(141±47 kPa)降低了60%.我们发现,鱼鳞在受到剪切力的过程中,会发生独特的结构演变,从而导致界面连续断裂,有利于降低冰的黏附性.研究发现,鱼鳞的张开和剥离能力(描述了鳞片在外力下与其下部鳞片和黏结物分离的趋势)可以调控冰的脱落.通过提高鱼鳞的张开和剥离能力,可以在鱼鳞上实现更低的冰黏附强度(66±15 kPa)和更为容易的除冰过程.由于鱼鳞具有出色的机械鲁棒性,这一发现为设计坚硬耐用的防覆冰表面提供了新的视角.

关键词： fish scale ice adhesion dynamic behaviors sequential rupture anti-icing

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