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Plastic deformation of a Zr-based bulk metallic glass fabricated by selective laser melting

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Journal of Materials Science & Technology 2021年第1期60卷 139-146页

作者： L.Deng k.kosiba R.Limbach L.Wondraczek U.kühn S.Pauly IFW Dresden Institute for Complex MaterialsHelmholtzstraße 20D-01069DresdenGermany Otto Schott Institute of Materials Research University of JenaFraunhoferstraße 6D-07743JenaGermany University of Applied Sciences Aschaffenburg Würzburger Straße 45D-63743AschaffenburgGermany

Fully amorphous Zr_(52.5)Cu_(17.9)Ni_(14.6)Al_(10)Ti_(5) bulk metallic glass(BMG) samples with a relative density exceeding 98% were fabricated via selective laser melting(SLM).High fracture stresses of around1700 MPa and a reproducible plastic strain of about 0.5% were obtained for cylindrical SLM *** analysis of the observed serrations during compressive loading implies that the shear-band dynamics in the additively manufactured samples distinctly differ from those of the as-cast *** phenomenon appears to originate from the presence of uniformly dispersed spherical pores as well as from the more pronounced heterogeneity of the glass itself as revealed by instrumented *** these heterogeneities,the shear bands are straight and form in the plane of maximum shear *** manufacturing,hence,might not only allow for producing large BMG samples with complex geometries but also for manipulating their deformation behaviour through tailoring porosity and structural heterogeneity.

关键词： Powder bed fusion Selective laser melting Bulk metallic glass Serrated flow Heterogeneity

Microstructural Evolution and Mechanical Behaviour of Metastable Cu-Zr-Co Alloys

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Journal of Materials Science & Technology 2014年第6期30卷 584-589页

作者： S.Pauly k.kosiba P.Gargarella B.Escher k.k.Song G.Wang U.kühn J.Eckert IFW Dresden Institut für Komplexe Materialien HelmholtzstraBe 20D-01069 Dresden Germany Laboratory for Microstructures Shanghai University TU Dresden Institut für WerkstoffwissenschaftD-01062 Dresden Germany

Three different Cu-Zr-Co alloys, namely Cu40Zr37.5Co22.5, Cu42.5Zr45Co12.5 and Cu49Zr49Co2, were obtained by rapid cooling. The microstructure and phase formation of as-cast rods with diameters of 2 mm are compared with those of the respective ingots. An increasing Co content stabilises the B2 CuZr phase and leads to the precipitation of a ternary Cu-Zr-Co phase. The variation of the cooling rate affects the size of the B2 dendrites as well as the volume fraction and the morphology of the interdendritic phases. The mechanical properties were determined in compression and all alloys show a certain plastic deformability despite the presence of several binary and ternary intermetallic phases. The deformation mechanisms are discussed on the basis of the microstructures and the constituent phases.

关键词： Bulk metallic glasses Microstructural evolution Mechanical behaviour

Hierarchical microstructures and strengthening mechanisms of nano-TiC reinforced CoCrFeMnNi high-entropy alloy composites prepared by laser powder bed fusion

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Journal of Materials Science & Technology 2023年第5期136卷 245-259页

作者： Hongyu Chen konrad kosiba Tiwen Lu Ning Yao Yang Liu Yonggang Wang konda Gokuldoss Prashanth Challapalli Suryanarayana key Laboratory of Impact and Safety Engineering of Ministry of Education of China Ningbo UniversityNingbo 315211China Leibniz Institute for Solid State and Materials Research Dresden Institute for Complex MaterialsHelmholtzstr.2001069 DresdenGermany key Laboratory of Pressure Systems and Safety Ministry of EducationEast China University of Science and TechnologyShanghai 200237China Department of Mechanical and Industrial Engineering Tallinn University of Technology19086 TallinnEstonia Erich Schmid Institute of Materials Science Austrian Academy of SciencesA-8700 LeobenAustria CBCMT Vellore Institute of TechnologyVellore 632014Tamil NaduIndia Department of Mechanical and Aerospace Engineering University of Central FloridaOrlandoFL 32816-2450United States

High entropy alloys(HEAs)have recently received extensive attention due to their appealing mechani-cal performance given their simple phase *** study utilized laser powder bed fusion(LPBF)to fabricate high-performance HEA *** processing respective powder blends,LPBF enabled the fabrication of stronger composites with a uniformly distributed reinforcing ***,the impact of varying content of nano-scale TiC(1-3 wt%)particles for strengthening the CoCrFeMnNi HEA was *** microstructural features and mechanical properties of the HEA composites were investigated in *** introduction of nano-scale TiC into the HEA matrix encouraged the development of cross-scale hierarchical microstructure and eliminated the formation of oxide *** more nano-TiC led to a higher dislocation density and more refined microstructure in the HEA composites,whereas it posed little influence on the anisotropy of the HEA matrix which typically featured atexture along the building *** an optimized content of nano-TiC(1-2 wt%),the strength-ductility trade-offcan be overcome by exploiting multiple strengthening mechanisms encompassing grain boundary strengthening,solid solution strengthening,Orowan strengthening,and dislocation *** HEA composites showed a favored strength-ductility combination with a yield strength of 748-882 MPa,ultimate tensile strength of 931-1081 MPa,and fracture elongation of 23%-29%.This study demonstrates that the introduction of nano-scale TiC is an effective way to simultaneously improve the strength and ductility of additively manufactured HEA materials.

关键词： Additive manufacturing Laser powder bed fusion High entropy alloy Microstructure Mechanical property

Achieving exceptional wear resistance in a crack-free high-carbon tool steel fabricated by laser powder bed fusion without pre-heating

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Journal of Materials Science & Technology 2023年第25期156卷 1-19页

作者： konrad kosiba Daniel Wolf Matthias Bönisch kai Neufeld Ruben Hühne Tobias Gustmann Jozef Bednarčík Hongyu Chen Xiaoliang Han Volker Hoffmann Lukas Beyer Uta kühn Sergio Scudino Lars Giebeler Julia k.Hufenbach Leibniz Institute for Solid State and Materials Research (IFW) Dresden E.V. Helmholtzstr. 20Dresden 01069Germany Department of Materials Engineering KU LeuvenKasteelpark Arenberg 44bus 2450Leuven 3001Belgium Department of Condensed Matter Physics Institute of PhysicsP.J. Safarik University in KosicePark Angelinum 9Kosice 04154Slovakia Institute of Experimental Physics Slovak Academy of ScienceWatsonova 47Kosice 040 01Slovakia key Laboratory of Impact and Safety Engineering of Ministry of Education of China Ningbo UniversityNingbo 315211China TU Bergakademie Freiberg Institute of Materials ScienceGustav-Zeuner-Str. 5Freiberg 09599Germany

Laser powder bed fusion(LPBF)for the fabrication of dense components used for tooling applications,is highly *** stresses,which evolve in the additively manufactured part,are inherent to LPBF *** additional stress contribution in high-carbon steels arises from the austenite-to-martensite phase transformation,which may eventually lead to cracking or even *** an alternative to pre-heating the base plate,which is not striven by industry,lowering the martensite content which forms in the part,is essential for the fabrication of dense parts by LPBF of high-carbon tool steels which are then adapted to *** this study,a successful strategy demonstrates the processing of the Fe85Cr4Mo1V1W8C1(wt%)high-carbon steel by LPBF into dense parts(99.8%).The hierarchical microstructure consists of austenitic and martensitic grains separated by elemental segregations in which nanoscopic carbide particles form a network.A high density of microsegregation was observed at the molten pool boundary ultimately forming a *** LPBF-fabricated steel shows a yield strength,ultimate compressive stress,and total strain of 1210 MPa,3556 MPa,and 27.4%,*** mechanical and wear performance is rated against the industrially employed and highly wear-resistant 1.2379 tool steel taken as the *** its lower macro-hardness,the LPBF steel(58.6 HRC,0.0061 mm^(3) Nm^(-1))shows a higher wear resistance than the reference steel(62.6 HRC,0.0078 mm^(3) Nm^(-1)).This behavior results from the wear-induced formation of martensite in a microscale thick layer directly at the worn surface,as it was proven via high-energy X-ray diffraction mapping.

关键词： Additive manufacturing Laser powder bed fusion Steel Wear TRIP

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 ***,a relatively limited number of such systems,where austenite and glassy matrix coexist over a wide range of compositions,is ***,we study the effective-ness of powder metallurgy as an alternative to solidification for the synthesis of shape memory ***_(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 *** results demonstrate that shape-memory BMGCs with tun-able microstructures and properties can be synthesized by hot *** 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 *** 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

Laser additive manufactured high-performance Fe-based composites with unique strengthening structure

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Journal of Materials Science & Technology 2021年第30期89卷 242-252页

作者： Hongyu Chen Dongdong Gu Liang Deng Tiwen Lu Uta kühn konrad kosiba College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Provincial Engineering Laboratory for Laser Additive Manufacturing of High-Performance Metallic Components Nanjing University of Aeronautics and AstronauticsNanjing 210016China Leibniz IFW Dresden Institute for Complex MaterialsP.O.Box 270116D-01069 DresdenGermany

Steel matrix composites(SMCs),reinforced by ceramic particles,have received a consistent attention in recent *** conventional methods to prepare SMCs is generally challenging,and the mechanical properties of conventionally fabricated SMCs are *** this study,we successfully fabricated highperformance SMCs by laser powder bed fusion(LPBF)of a composite powder consisting of Fe-based alloy powder and submicron-sized WC *** effect of laser energy density on the phase formation,microstructural evolution,overall density and resulting mechanical properties of LPBF-fabricated composites was *** present results show that a novel Fe_(2)W_(4)C carbidic network precipitates in the solidified microstructure entailing segregations along the boundaries of cellular *** presence of this carbidic network hampers the growth of sub-grains even at elevated temperatures,and hence,stabilizes the grain size though prepared at a broad range of different energy *** exact distribution of the Fe_(2)W_(4)C carbides depends on the employed laser energy densities,as for instance they are more uniformly distributed at higher energy *** density of LPBF samples reaches the maximum value of 99.4%at 150 J/mm^(3).In this parameter set,high microhardness of~753 HV,compression strength of~3350 MPa and fracture strain of~24.4%are *** enhanced mechanical properties are ascribed to less metallurgical defects,higher volume fraction of the martensitic phase and increasing pile-up dislocations resulting from the pinning effect by Fe_(2)W_(4)C carbide.

关键词： Laser additive manufacturing Laser powder bed fusion Steel matrix composite Microstructures Mechanical properties

CuZr-based bulk metallic glass and glass matrix composites fabricated by selective laser melting

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Journal of Materials Science & Technology 2021年第22期81卷 139-150页

作者： Liang Deng Long Zhang konrad kosiba RenéLimbach Lothar Wondraczek Gang Wang Dongdong Gu Uta kühn Simon Pauly Leibniz IFW Dresden Institute for Complex MaterialsHelmholtzstraße 20D-01069DresdenGermany Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Otto Schott Institute of Materials Research University of JenaFraunhoferstraße 6D-07743 JenaGermany Laboratory for Microstructure Institute of MaterialsShanghai UniversityShanghai200444China College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing210016China University of Applied Sciences Aschaffenburg Würzburger Straße 45D-63743AschaffenburgGermany

Monolithic bulk metallic glass and glass matrix composites with a relative density above 98%were produced by processing Cu_(46)Zr_(46)Al_(8)(at.%)via selective laser melting(SLM).Their microstructures and mechanical properties were systematically examined.B2 CuZr nanocrystals(30-100 nm in diameter)are uniformly dispersed in the glassy matrix when SLM is conducted at an intermediate energy *** B2 CuZr nanocrystals nucleate the oxygen-stabilized big cube phase during a remelting *** presence of these nanocrystals increases the structural heterogeneity as indirectly revealed by mircrohardness and nanoindentation *** corresponding maps in combination with calorimetric data indicate that the glassy phase is altered by the processing *** the formation of crystals and a high overall free volume content,all additively manufactured samples fail at lower stress than the as-cast glass and without any plastic *** inherent brittleness is attributed to the presence of relatively large pores and the increased oxygen content after selective laser melting.

关键词： Selective laser melting CuZr-based glass Bulk metallic glass matrix composites Phase formation Mechanical properties

Phase formation of a biocompatible Ti-based alloy under kinetic constraints studied via in-situ high-energy X-ray diffraction

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Progress in Natural Science:Materials International 2020年第3期30卷 432-436页

作者： konrad kosiba André Rothkirch Junhee Han Liang Deng Benjamin Escher Gang Wang Uta kühn Jozef Bednarcik Leibniz IFW Dresden Institute for Complex Materials DESY Photon Science 3. korea Institute of Industrial Technology (kITECH) Korea Institute for Rare Metals 4. Fraunhofer Institute for Photonic Microsystems IPMS Department of Engineering 5. Laboratory for Microstructures Institute of Materials Shanghai University 6. J. Safarik University in Kosice Institute of Physics Department of Condensed Matter Physics

The biocompatible Ti40Cu34Pd14Zr10Sn2bulk metallic glass was rapidly heated,also known as flash-annealed,at varying heating rates up to 1579 k/***,the phase formation was characterized via advanced in-situ highenergy X-ray *** has been found that the evolving kinetic constraints can be used as a tool to deliberately alter the crystalline phase *** novel processing route permits to select phases to crystallize to a predefined fraction and,thus,to potentially design the microstructure of materials according to a specified ***,flash-annealing poses a unique synthesis route to design materials with,for instance,good biomechanical compatibility.

关键词： High-energy X-ray diffraction Flash-annealing Phase formation Metallic glass Biocompatible Ti alloy

Role of laser scan strategies in defect control,microstructural evolution and mechanical properties of steel matrix composites prepared by laser additive manufacturing

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International Journal of Minerals,Metallurgy and Materials 2021年第3期28卷 462-474页

作者： Hong-yu Chen Dong-dong Gu Qing Ge Xin-yu Shi Hong-mei Zhang Rui Wang Han Zhang konrad kosiba College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Provincial Engineering Laboratory for Laser Additive Manufacturing of High-Performance Metallic Components Nanjing University of Aeronautics and AstronauticsNanjing 210016China Leibniz IFW Dresden Institute for Complex MaterialsHelmholtzstr.2001069 DresdenGermany

Steel matrix composites(SMCs)reinforced with WC particles were fabricated via selective laser melting(SLM)by employing various laser scan strategies.A detailed relationship between the SLM strategies,defect formation,microstructural evolution,and mechanical properties of SMCs was *** laser scan strategies can be manipulated to deliberately alter the thermal history of SMC during SLM ***,the involved thermal cycling,which encompassed multiple layers,strongly affected the processing quality of *** scan sequence combined with interlayer offset and orthogonal stagger mode can effectively eliminate the metallurgical defects and retained austenite within the produced ***,due to large thermal stress,microcracks that were perpendicular to the building direction formed within the *** employing the checkerboard filling(CBF)hatching mode,the thermal stress arising during SLM can be significantly reduced,thus preventing the evolution of interlayer *** compressive properties of fabricated SMCs can be tailored at a high compressive strength(~3031.5 MPa)and fracture strain(~24.8%)by adopting the CBF hatching mode combined with the optimized scan sequence and stagger *** study demonstrates great feasibility in tuning the mechanical properties of SLM-fabricated SMCs without varying the set energy input,e.g.,laser power and scanning speed.

关键词： laser additive manufacturing selective laser melting scan strategy defect control mechanical property