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Impact of Si on the high-temperature oxidation of AlCr(Si)N coatings

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Journal of materials science & Technology 2022年第5期100卷 91-100页

作者： Nikolaus Jager Michael Meindlhumer Michal Zitek Stefan Spor Hynek Hruby Farwah Nahif Jaakko Julin Martin Rosenthal Jozef Keckes Christian Mitterer Rostislav Daniel Christian Doppler Laboratory for Advanced Synthesis of Novel Multifunctional Coatings at the Department of materials science Montanuniversität LeobenAustria voestalpine eifeler Vacotec GmbH DüsseldorfGermany institute of Ion Beam Physics and materials Research Helmholtz-Zentrum Dresden-RossendorfDresdenGermany Department of Physics University of JyvaskylaFinland European Synchrotron Radiation Facility GrenobleFrance erich schmid institute for materials science Austrian Academy of SciencesAustria Department of materials science Montanuniversität LeobenAustria

The resistance of wear protective coatings against oxidation is crucial for their use at high temperatures.Here,three nanocomposite AlCr(Si)N coatings with a fixed Al/Cr atomic ratio of 70/30 and a varying Si-content of 0 at.%,2.5 at.% and 5 at.% were analyzed by differential scanning calorimetry,thermogravimetric analysis and X-ray in order to understand the oxidation behavior depending on their Si-content.Additionally,a partially oxidized AlCrSiN coating with 5 at.%Si on a sapphire substrate was studied across the coating thickness by depth-resolved cross-sectional X-ray nanodiffraction and scanning trans-mission electron microscopy to investigate the elemental composition,morphology,phases and residual stress evolution of the oxide scale and the non-oxidized coating underneath.The results reveal enhanced oxidation properties of the AlCr(Si)N coatings with increasing Si-content,as demonstrated by a retarded onset of oxidation to higher temperatures from 1100℃ for AlCrN to 1260℃ for the Si-containing coatings and a simultaneous deceleration of the oxidation process.After annealing of the AlCrSiN sample with5 at.%Si at an extraordinary high temperature of 1400℃ for 60 min in ambient air,three zones developed throughout the coating strongly differing in their composition and structure:(i)a dense oxide layer comprising an Al-rich and a Cr-rich zone formed at the very top,followed by(ii)a fine-grained transition zone with incomplete oxidation and(iii)a non-oxidized zone with a porous structure.The varying elemental composition of these zones is furthermore accompanied by micro-structural variations and a complex residual stress development revealed by cross-sectional X-ray nanodiffraction.The results provide a deeper understanding of the oxidation behavior of AlCr(Si)N coatings depending on their Si-content and the associated elemental,microstructural and residual stress evolution during high-temperature oxidation.

关键词： AlCrSiN Nanocomposite Cathodic arc Oxidation behaviour Cross-sectional X-ray nanodiffraction

Strengthening and deformation mechanism of high-strength CrMnFeCoNi high entropy alloy prepared by powder metallurgy

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Journal of materials science & Technology 2023年第1期132卷 119-131页

作者： Y.Xing C.J.Li Y.K.Mu Y.D.Jia K.K.Song J.Tan G.Wang Z.Q.Zhang J.H.Yi J.Eckert Faculty of materials science and Engineering Kunming University of Science and TechnologyKunming 650093China Laboratory for Microstructures Institute of MaterialsShanghai UniversityShanghai 200444China School of Mechanical Electrical&Information EngineeringShandong UniversityWeihai 264209China College of materials science and Engineering Chongqing UniversityChongqing 400044China Erich Schmid Institute of Materials Science Austrian Academy of SciencesJahnstraße 12Leoben A-8700Austria Department of materials science Chair of Materials PhysicsMontanuniversität LeobenJahnstraße 12Leoben A-8700Austria Adjunct with National University of science and Technology«MISiS» Leninsky Prosp.4Moscow 119049Russia

Multiphase CrMnFeCoNi high-entropy alloys(HEAs)were prepared by a powder metallurgy process com-bining mechanical alloying(MA)and vacuum hot-pressing sintering(HPS).The single-phase face-centered cubic(FCC)HEA powder prepared by MA was sintered into a bulk HEA specimen containing FCC phase matrix along with precipitated M 23 C 6 phase and nanoscaleσphase particles.When the sintering temper-ature was 1223 K,the ultimate strength reaches 1300±11.6 MPa,and the elongation exceeds 4%±0.6%.Microstructural characterization reveals that the formation of nanoscale particles and deformation twins play critical roles in improving the strain hardening(SH)ability.Prolonging the MA time promoted the formation of the precipitated phase and enhanced the SH ability by increasing the number of precip-itated particles.The SH capacity increases significantly with increasing sintering temperature,which is attributed to a significant enhancement in the twinning capacity due to grain growth and the reduced number ofσphase particles.Through systematic studies,the planar glide of dislocations was found to be the main mode of deformation,while deformation twinning appeared as an auxiliary deformation mode when the twinning stress was reached.Although the formation of precipitates leads to grain bound-ary and precipitation strengthening effects,crack initiation is more prominent owing to increased grain boundary brittleness around the precipitated M 23 C 6 phase.The prominence of crack initiation is a contra-diction that must be reconciled with regard to precipitation strengthening.This work serves as a useful reference for the preparation of high-strength HEA parts by powder metallurgy.

关键词： High entropy alloy Powder processing Grain reﬁnement Precipitation strengthening Deformation twinning

Accelerating matrix/boundary precipitations to explore high-strength and high-ductile Co_(34)Cr_(32)Ni_(27)Al_(3.5)Ti_(3.5) multicomponent alloys through hot extrusion and annealing

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Journal of materials science & Technology 2023年第12期143卷 62-83页

作者： Xiaoming Liu Zongde Kou Ruitao Qu Weidong Song Yijia Gu Changshan Zhou Qingwei Gao Jiyao Zhang Chongde Cao Kaikai Song Vladislav Zadorozhnyy Zequn Zhang Jürgen Eckert Shenzhen Research institute of Shandong University Shenzhen 518057China State Key Laboratory of Explosion science and Technology Beijing Institute of TechnologyBeijing 100081China School of Mechanical Electrical&Information EngineeringShandong UniversityWeihai 264209China School of Material science and Engineering Nanjing University of Science and TechnologyNanjing 210094China School of materials science and Engineering Northwestern Polytechnical UniversityXi’an 710072China Department of materials science and Engineering Missouri University of Science and TechnologyRollaMO 65409USA Research and Development institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China National University of science and Technology«MISIS» Moscow 119049Russia Erich Schmid Institute of Materials Science Austrian Academy of SciencesLeoben A-8700Austria Department of materials science Montanuniversität LeobenLeoben A-8700Austria

Annealing-regulated precipitation strengthening combined with cold-working is one of the most efficient strategies for resolving the conflict between strength and ductility in metals and alloys.However,precipitation control and grain refinement are mutually contradictory due to the excellent phase stability of multicomponent alloys.This work utilizes the high-temperature extrusion and annealing to optimize the microstructures and mechanical properties of the Co_(34)Cr_(32)Ni_(27)Al_(3.5)Ti_(3.5) multicomponent alloy.Hot extrusion effectively reduces grain sizes and simultaneously accelerates the precipitation of coherent L12 nanoparticles inside the face-centered cubic(FCC)matrix and grain boundary precipitations(i.e.,submicron Cr-rich particles and L12-Ni 3(Ti,Al)precipitates),resulting in strongly reciprocal interaction between dislocation slip and hierarchical-scale precipitates.Subsequent annealing regulates grain sizes,dislocations,twins,and precipitates,further allowing to tailor mechanical properties.The high yield strength is attributed to the coupled precipitation strengthening effects from nanoscale coherent L12 particles inside grains and submicron grain boundary precipitates under the support of pre-existing dislocations.The excellent ductility results from the synergistic activation of dislocations,stacking faults,and twins during plastic deformation.The present study provides a promising approach for regulat-ing microstructures,especially defects,and enhancing the mechanical properties of multicomponent alloys.

关键词： Multicomponent alloys Hot extrusion Microstructure Mechanical properties Precipitation strengthening

Mechanical behavior and deformation mechanism of shape memory bulk metallic glass composites synthesized by powder metallurgy

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Journal of materials science & Technology 2022年第19期114卷 42-54页

作者： Tianbing He Tiwen Lu Daniel Sopu Xiaoliang Han Haizhou Lu Kornelius Nielsch Jürgen Eckert Nevaf Ciftci Volker Uhlenwinkel Konrad Kosiba Sergio Scudino Leibniz IFW Dresden Institute for Complex MaterialsHelmholtzstraße 2001069 DresdenGermany Guangdong Key Laboratory for Advanced Metallic materials Processing South China University of TechnologyGuangzhou 510640China Erich Schmid Institute of Materials Science Austrian Academy of SciencesJahnstraße 12Leoben A-8700Austria Leibniz IFW Dresden Institute for Metallic MaterialsHelmholtzstraße 2001069 DresdenGermany TU Dresden Institute of Materials Science01062 DresdenGermany TU Dresden Institute of Applied Physics01062 DresdenGermany Department materials Physics Montanuniversität LeobenJahnstraße 12A-8700 LeobenAustria Leibniz institute for materials Engineering IWT 28359 BremenGermany University of Bremen Faculty of Production Engineering28359 BremenGermany

The synthesis of martensitic or shape-memory bulk metallic glass composites(BMGCs)via solidification of the glass-forming melts requires the meticulous selection of the chemical composition and the proper choice of the processing parameters in order to ensure that the glassy matrix coexists with the desired amount of austenitic phase.Unfortunately,a relatively limited number of such systems,where austenite and glassy matrix coexist over a wide range of compositions,is available.Here,we study the effective-ness of powder metallurgy as an alternative to solidification for the synthesis of shape memory BMGCs.Zr_(48)Cu_(36)Al_(8)Ag_(8)matrix composites with different volume fractions of Ni_(50.6)Ti_(49.4)are fabricated using hot pressing and their microstructure,mechanical properties and deformation mechanism are investigated employing experiments and simulations.The results demonstrate that shape-memory BMGCs with tun-able microstructures and properties can be synthesized by hot pressing.The phase stability of the glass and austenitic components across a wide range of compositions allows us to examine fundamental as-pects in the field of shape memory BMGCs,including the effect of the confining stress on the martensitic transformation exerted by the glassy matrix,the contribution of each phase to the plasticity and the mechanism responsible for shear band formation.The present method gives a virtually infinite choice among the possible combinations of glassy matrices and shape memory phases,expanding the range of accessible shape memory BMGCs to systems where the glassy and austenitic phases do not form simul-taneously using the solidification route.

关键词： Metallic glass composites Niti alloys Mechanical properties Shear bands Martensitic transformation

Enhanced mechanical performance of gradient-structured CoCrFeMnNi high-entropy alloys induced by industrial shot-blasting

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Rare Metals 2023年第3期42卷 982-993页

作者： Ming-Zhi Zhang Kun Zhang Kai-Kai Song Xiao-Yu Zou Wei-Dong Song Ke-Feng Li Li-Na Hu Ze-Qun Zhang Jürgen Eckert Shenzhen Research institute of Shandong University Shenzhen 518057China CAS Key Laboratory of Microgravity(National Microgravity Laboratory) Institute of MechanicsChinese Academy of SciencesBeijing100190China State Key Laboratory of Explosion science and Technology Beijing Institute of TechnologyBeijing 100081China School of Mechanical Electrical and Information EngineeringShandong UniversityWeihai 264209China Guangdong institute of materials and Processing Guangdong Academy of SciencesGuangzhou 510650China Key Laboratory for Liquid-Solid Structural Evolution and Processing of materials(Ministry of Education) Shandong UniversityJinan 250061China Erich Schmid Institute of Materials Science Austrian Academy of SciencesLeoben 8700Austria Department of materials science Montanuniversitat LeobenLeoben 8700Austria

In this study,CoCrFeMnNi high-entropy alloys(HEAs)with a surface gradient nanostructure were produced using industrial shot blasting,which improved their mechanical properties compared to the untreated alloy.The severely plastically deformed(SPD)surface layer had a multi-scale hierarchical structure with a high density of stacking faults,deformation nanotwins,and amorphous domains.The depth of the SPD layer steadily increased as the shot-blasting time increased.The differences in the microhardness and tensile strength before and after shotblasting demonstrated the significant effect of the SPD layer on the mechanical performance.The microhardness of the homogenized HEA was~5 GPa.In comparison,the maximum microhardness of the specimens after 20 min of shot blasting was~8.0 GPa at the surface.The yield strength also improved by 178%,and a large ductility of~36%was retained.Additional nanograin boundary,stacking fault,and twin strengthening within the gradientnanostructured surface layer caused the strength to increase.During tensile deformation,strain concentration began at the surface of the specimen and gradually spread to the interior.Thus,the gradient-nanostructured surface layer with improved strain hardening can prevent early necking and ensure steady plastic deformation so that high toughness is achieved.

关键词： High-entropy alloy Shot blasting Gradient structure Mechanical property Deformation mechanism

Stress-rupture measurements of cast magnesium strengthened by in-situ production of ceramic particles

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Journal of Magnesium and Alloys 2017年第2期5卷 225-230页

作者： Nagaraj M.Chelliah Sudarshan Lisa Kraemer Harpreet Singh M.K.Surappa Rishi Raj Department of Mechanical Engineering University of Colorado BoulderBoulderCO 80302USA Department of Mechanical Engineering Indian Institute of TechnologyRopar 140001India erich schmid institute of Material science Austrian Academy of SciencesLeobenA-8700Austria Department of materials Engineering Indian Institute of ScienceBangalore 560012India

We have introduced a polymer precursor into molten magnesium and then in-situ pyrolyzed to produce castings of metal matrix composites(P-MMCs)containing silicon-carbonitride(SiCNO)ceramic particles.Stress-rupture measurements of as-cast P-MMCs was performed at 350 ℃(0.69TM)to 450 ℃(0.78TM)under dead load condition corresponding to tensile stress of 2.5 MPa to 20 MPa.The time-to-fracture data were analyzed using the classical Monkman–Grant equation.The time-to-fracture is thermally activated and follows a power-law stress exponent exhibiting dislocation creep.Fractography analysis revealed that while pure magnesium appears to fracture by dislocation slip,the P-MMCs fail from the nucleation and growth of voids at the grain boundaries.

关键词： Stress-rupture Polymer derived ceramics Magnesium Dispersion strengthened alloys High temperature Light-weight materials

Rapid solidification and metastable phase formation during surface modifications of composite Al-Cr cathodes exposed to cathodic arc plasma

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Journal of materials science & Technology 2021年第35期94卷 147-163页

作者： Mehran Golizadeh Francisca Mendez Martin Stefan Wurster Johann P.Mogeritsch Abdellah Kharicha Szilard Kolozsvári Christian Mitterer Robert Franz Department of materials science Montanuniversitat LeobenFranz Josef-Straβe 188700 LeobenAustria Erich Schmid Institute of Materials Science Austrian Academy of SciencesJahnstraβe 12.8700 LeobenAustria Department of Metallurgy Montanuniversitat LeobenFranz Josef-Straβe 188700 LeobenAustria Plansee Composite materials GmbH Siebenbiirgerstraβe 2386983 Lechbruck am SeeCermany

A combination of both conventional and advanced high-resolution characterization techniques was applied to study the modified layers on the surface of three composite Al-Cr arc cathodes with identical nominal composition of Al-50 at.%Cr but varying powder grain sizes.The results revealed that the modified layers consist mainly of metastable phases such as Cr solid solution,high temperature cubic Al8 Cr5,supersaturated Al solid solution,and icosahedral quasicrystal.The metastable phase formation indicates that high cooling rates were involved during the solidification of molten material produced in the arc craters during cathode spot events.The average cooling rate was estimated to be 10^(6)K/s based on secondary dendrite arm spacing measurements and supporting phase-field based simulations.The formation mechanisms of the modified layers are discussed based on the obtained results and the current literature.

关键词： Cathodic arc Rapid solidification Quasicrystal Arc crater Macroparticle Phase-field simulation

Structural homology of the strength for metallic glasses

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Journal of materials science & Technology 2021年第22期81卷 123-130页

作者： Weiming Yang Xinfa Sun Haishun Liu Changfeng Yu Wenyu Li Akihisa Inoue DanielŞopud Jürgen Eckert Chunguang Tang School of Mechanics and Civil Engineering State Key Laboratory for Geomechanics and Deep Underground EngineeringChina University of Mining and TechnologyXuzhou 221116China Departments of Physics College of ScienceXi’an Polytechnic UniversityXi’an 710048 China International institute of Green materials Josai International UniversityTogane283-8555Japan Erich Schmid Institute of Materials Science Austrian Academy of Science8700 LeobenAustria Department of materials science Chair of Materials PhysicsMontanuniversität Leoben8700 LeobenAustria Research School of Chemistry Energy Change InstituteAustralian National UniversityCanberra ACT 2601Australia

The structure-property relationship,one of the central themes in materials science,is far from being well understood for metallic glasses(MGs)due to the great complexity of their amorphous structures.Based on the analysis of published experimental data for 165 MGs from more than 15 different alloy systems,the present study reveals a universal dependence of mechanical properties(Young’s moduli,shear moduli and yield strength)on simple structural parameters(the inter-atomic distance and/or valence electron density)originating from the interatomic potential and Fermi sphere-Brillouin zone interaction.This work establishes a structure-property relationship for metallic glasses and provides insights into the fundamentals of the mechanical properties of disordered systems.

关键词： Metallic glasses Structure-property relationship Mechanical properties Inter-atomic distance Valence electron density

Selective Laser Melting of Al-7Si-0.5Mg-0.5Cu:Effect of Heat Treatment on Microstructure Evolution,Mechanical Properties and Wear Resistance

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Acta Metallurgica Sinica(English Letters) 2022年第3期35卷 389-396页

作者： Pei Wang Sijie Yu Jaskarn Shergill Anil Chaubey Jürgen Eckert Konda Gokuldoss Prashanth Sergio Scudino Additive Manufacturing institute College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen 518060China institute for Complex materials IFW DresdenHelmholtzstraBe 2001069 DresdenGermany institute of Minerals and materials Technology(IMMT) Bhubaneshwar 751013OrissaIndia Erich Schmid Institute of Materials Science Austrian Academy of SciencesJahnstraBe 128700 LeobenAustria Department of materials science Chair of Materials PhysicsMontanuniversitat LeobenJahnstraBe 128700 LeobenAustria Department of Mechanical and Industrial Engineering Tallinn University of TechnologyEhitajete tee 519086 TallinnEstonia CBCMT School of Mechanical EngineeringVellore Institute of TechnologyVellore.Tamil Nadu 632014India Adjunct With National University of science and Technology aMISi Sa Leninsky Prosp..4.119049 MoscowRussia

Al-7Si-0.5Mg-0.5Cu alloy specimens have been fabricated by selective laser melting(SLM).In this study,the effects of solution treatment,quenching,and artifi cial aging on the microstructural evolution,as well as mechanical and wear properties,have been investigated.The as-prepared samples show a heterogeneous cellular microstructure with two different cell sizes composed ofα-Al and Si phases.After solution-treated and quenched(SQ)heat treatment,the cellular microstructure disappears,and coarse and lumpy Si phase precipitates and a rectangular Cu-rich phase were observed.Subsequent aging after solution-treated and quenched(SQA)heat treatment causes the formation of nanosized Cu-rich precipitates.The asprepared SLMs sample has good mechanical properties and wear resistance(compressive yield strength:215±6 MPa and wear rate 2×10^(-13)m^(3)/m).The SQ samples with lumpy Si particles have the lowest strength of 167±13 MPa and the highest wear rate of 6.18×10^(1-13)m^(3)/m.The formation of nanosized Cu-rich precipitates in the SQA samples leads to the highest compressive yield strength of 233±6 MPa and a good wear rate of 5.06×10^(-13)m^(3)/m.

关键词： Selective laser melting Al-Si-Cu-Mg alloy Heat treatment Microstructure Mechanical properties Wear properties