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Effect of Powder Particle Shape on the Properties of In Situ Ti–TiB Composite Materials Produced by Selective Laser Melting

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Journal of Materials Science & Technology 2015年第10期31卷 1001-1005页

作者： Hooyar Attar Konda G.Prashanth Lai-Chang Zhang Mariana Calin ilya v.okulov Sergio Scudino Chao Yang Jürgen Eckert School of Engineering Edith Cowan University IFW Dresden Institute for Complex Materials TU Dresden Institute of Materials Science National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials South China University of Technology

This work studied the preparation of starting powder mixture influenced by milling time and its effect on the particle morphology （especially the shape） and, consequently, density and compression properties of in situ Ti-TiB composite materials produced by selective laser melting （SLM） technology. Starting powder composite system was prepared by mixing 95 wt% commercially pure titanium （CP-Ti） and 5 wt% titanium diboride （TiB2） powders and subsequently milled for two different times （i.e. 2 h and 4 h）. The milled powder mixtures after 2 h and 4 h show nearly spherical and irregular shape, respectively. Subsequently, the resultant Ti-5 wt% TiB2 powder mixtures were used for SLM processing. Scanning electron microscopy image of the SLM-processed Ti-TiB composite samples show needle-shape TiB phase distributed across the Ti matrix, which is the product of an in-situ chemical reaction between Ti and TiB2 during SLM. The Ti-TiB composite samples prepared from 2 h and 4 h milled Ti-TiB2 powders show different relative densities of 99.5% and 95.1%, respectively. Also, the compression properties such as ultimate strength and compression strain for the 99.5% dense composite samples is 1421 MPa and 17.8%, respectively, which are superior to those （883 MPa and 5.5%, respectively） for the 95.1% dense sample. The results indicate that once Ti and TiB2 powders are connected firmly to each other and powder mixture of nearly spherical shape is obtained, there is no additional benefit in increasing the milling time and, instead, it has a negative effect on the density （i.e. increasing porosity level） of the Ti-TiB composite materials and their mechanical properties.

关键词： Selective laser melting In situ Ti-TiB composite Powder shape Density Mechanical properties

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Inhomogeneous dealloying kinetics along grain boundaries during liquid metal dealloying

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Journal of Materials Science & Technology 2022年第11期106卷 41-48页

作者： S.-H.Joo Y.B.Jeong T.Wada I.v.okulov H.Kato Department of Materials Science and Engineering Dankook University119 Dandae-roCheonan 31116Korea Institute for Materials Research Tohoku UniversityKatahira 2-1-1Sendai 980-8577Japan Institute of Natural Sciences and Mathematics Ural Federal University620000 EkaterinburgRussia Faculty of Production Engineering University of BremenBadgasteiner Str.128359 BremenGermany Leibniz Institute for Materials Engineering-IWT Badgasteiner Str.328359 BremenGermany

In this study, the inhomogeneous dealloying phenomenon during the liquid metal dealloying(LMD) was investigated using FeNi+Mg and(FeCo)Ni+Mg systems. For the FeNi+Mg system, the inhomogeneous dealloying and wetting of Mg melt occurred along triple junction(TJ) and grain boundary(GB).Temperature increase enhances the inhomogeneous dealloying kinetics and leads to the formation of the plate-shaped abnormal ligaments at the GB region. The energy banlance between a GB energy(γGB)and solid-liquid interface energies(γsl) is the key factor governing the inhomogeneous dealloying and wetting. Particularly, the low-energy twin boundaries were unaffected by the inhomogeneous dealloying.Therefore, precursor microstructure is an important factor determining the final morphology of dealloyed material as well as its physical properties. In the case of the(FeCo)Niprecursor, all TJ and GB were stable against the preferred penetration of Mg melt from 600 ℃ to 800 ℃. It was concluded that a minor addition of alloying elements(vorCr) changes GB characteristics as well as γslof the precursor alloy.Consequently, this significantly influences dealloying mechanisms and final morphology of the dealloyed material. The current findings demonstrate the importance of GB engineering in the precursor materials for the technological application of liquid metal dealloying for the synthesis of advanced structural and functional materials.

关键词： Liquid metal dealloying Inhomogeneous dealloying Dealloying mechanism Abnormal ligament Porous material

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Nanoporous magnesium

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Nano Research 2018年第12期11卷 6428-6435页

作者： ilya vladimirovich okulov Sviatlana v.Lamaka Takeshi Wada Kunio Yubuta Mikhail L.Zheludkevich Jorg Weissmuller Jurgen Markmann Hidemi Kato Institute for Materials Research Tohoku UniversityKatahira 2-1-1Sendai980-8577Japan Institute of Materials Research Materials MechanicsHelmholtz-Zentrum Geesthacht21502GeesthachtGermany MagiC-Magnesium Innovation Centre Helmholtz-Zentrum Geesthacht21502GeesthachtGermany Faculty of Engineering University of Kiel24118KielGermany Institute of Materials Physics and Technology Hamburg University of Technology21073HamburgGermany

In this study, we present freestanding nanoporous magnesium as a novel lightweight material with high potential for structural and functional applications. Thus far, the high reactivity of Mg with oxygen and aqueous media prevented the fabrication of nanoporous Mg. First, in order to synthesize nanoporous Mg, we fabricated a bicontinuous nanocomposite consisting of interpenetrating Mg and non-Mg phases by liquid metal dealloying. The non-Mg phases in the nanocomposite protect Mg against corrosion. Second, we etched the non-Mg phases from the nanocomposite, leaving nanoporous Mg, using HF solution. This process is advantageous because the nanoporous Mg was passivated by a MgF2 layer during the etching. Our approach is very flexible, and we demonstrate that versatile microstructures of the nanoporous Mg—e.g., nanoscale bicontinuous network, hierarchical, or plate-like structures—can be designed for the given needs. More importantly, these nanoporous Mg samples can readily be exposed to air without being harmed by corrosion.

关键词： dealloying nanoporous magnesium

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Genes associated with testicular germ cell tumors and testicular dysgenesis in patients with testicular microlithiasis

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Asian Journal of Andrology 2018年第6期20卷 593-599页

作者： ilya S Dantsev Evgeniy v Ivkin Aleksey A Tryakin Dmitriy N Godlevski Oleg Yu Latyshev victoriya v Rudenko Dmitry S Mikhaylenko vyacheslav B Chernykh Elena A volodko Aleksey B okulov Oleg B Loran Marina v Nemtsova Russian Medical Academy ef Postgraduate Education Moscow 123995 Russia N. N. Blokhin Russian Cancer Research Center Moscow 115478 Russia Research Centre of Medical Genetics Moscow 115478 Russia I. M. Sechenov First Moscow State Medical University Moscow 119991 Russia N. I. Pirogov Russian National Research Medical University Moscow 117997 Russia.

Testicular microlithiasis （TM） is one of the symptoms of testicular dysgenesis syndrome （TDS）. TM is particularly interesting as an informative marker of testicular germ cell tumors （TGCTs）. KIT ligand gene （KITLG）, BCL2 antagonist/killer 1 （BAK1）, and sprouty RTK signaling antagonist 4 （SPRY4） genes are associated with a high risk of TGCTs, whereas bone morphogenetic protein 7 gene （BMP7）, transforming growth factor beta receptor 3 gene （TGFBR3）, and homeobox D cluster genes （HOXD） are related to TDS. Using polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） analysis, we investigated allele and genotype frequencies for KITLG （rs995030, rs1508595）, SPRY4 （rs4624820, rs6897876）, BAK1 （rs210138）, BMP7 （rs388286）, TGFBR3 （rs12082710）, and HOXD （rs17198432） in 142 TGCT patients, 137 TM patients, and 153 fertile men （control group）. We found significant differences in the KITLG GG_rs995030 genotype in TM （P= 0.01） and TGCT patients （P = 0.0005） compared with the control. We also revealed strong associations between KITLGrs1508595 and TM （G allele, P = 0.003; GG genotype, P= 0.01） and between KITLG_rs1508595 and TGCTs （G allele, P-- 0.0001; GG genotype, P = 0.0007）. Moreover, there was a significant difference in BMP7_rs388286 between the TGCT group and the control （T allele, P = 0.00004; TT genotype, P = 0.00006） and between the TM group and the control （T allele, P= 0.04）. HOXDalso demonstrated a strong association with TGCTs （rs17198432 A allele, P = 0.0001; AA genotype, P = 0.001）. Furthermore, significant differences were found between the TGCT group and the control in the BAK1_rs210138 G allele （P= 0.03） and the GG genotype （P= 0.01）. KITLG and BMP7genes, associated with the development of TGCTs, may also be related to TM. In summary, the KITLG GG_rs995030, GG_rs1508595, BMP7 TT_rs388286, HOXD AA_rs17198432, and BAK1 GG_rs210138 genotypes were associated with a high risk of TGCT development.

关键词： associations genotype high risk testicular dysgenesis syndrome testicular microlithiasis

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