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microstructural development via synergic application of Binder Jetting and Quenching and Partitioning (QP) on commercial AISI 4340

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MATERIALS CHARACTERIZATION 2025年 222卷

作者： Belfi, M. Mariani, M. Martin, P. Santofimia, M. Gruttadauria, A. Deirmina, F. Lecis, N. Barella, S. Politecn Milan Dept Mech Engn I-20156 Milan Italy Delft Univ Technol Dept Mat Sci & Engn NL-2628 CD Delft Netherlands Sandvik Machining Solut AB Sandvik Addit Mfg Sandviken Sweden

This study investigates the microstructural development of commercial low-alloyed AISI 4340 steel through the synergistic application of Binder Jetting and Quenching and Partitioning (QP) processes. The material in the as- sintered condition exhibited significant variations in microstructure and mechanical properties, primarily influenced by the processing route. Carbon content was influenced by the building technique as decarburization was observed at different intensities mainly during the heating stage of sintering, driven by carbothermic reduction. Vacuum-debinding was found to be optimal, leading to the most homogeneous microstructure, predominantly granular bainite with superior hardness and tensile strength. Different QP treatments were optimized considering the decarburization effect on the optimal as-sintered condition, stabilizing 4-8 % retained austenite in a martensitic matrix, with optimal results observed after isothermal holding at either 220 degrees C or 240 degrees C for 30 min. These conditions resulted in high UTS values of 1231 MPa and 1151 MPa, respectively, compared to 750 MPa in the as-sintered state. Despite high tensile properties, A% was limited by the presence of residual porosity. This study highlights the critical importance of controlled debinding and sintering atmospheres as well as decarburization-informed QP treatments in achieving desirable microstructural and mechanical properties in additively manufactured AISI 4340 steel components.

关键词： AISI 4340 steel Binder jetting Quenching and partitioning Decarburization microstructural development

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microstructural development of MnCO3 microsphere compacts through hydrothermal hot-pressing

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JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 2022年第4期42卷 1530-1536页

作者： Kozawa, Takahiro Osaka Univ Joining & Welding Res Inst 11-1 Mihogaoka Ibaraki Osaka 5670047 Japan

Low-temperature sintering is a highly effective method for solidifying powders of thermally degradable mate-rials, such as carbonates and hydroxides. Hydrothermal hot-pressing (HHP) is a low-temperature sintering method that uses a dissolution-precipitation reaction to water under hydrothermal conditions. Most sintering techniques, including HHP, were devised to fabricate high-density compacts;hence, varying the internal microstructure during solidification is challenging. The present study focuses on the microstructural develop-ment of MnCO3 microsphere compacts through HHP. Depending on the HHP process temperature, the formation of MnOOH fibers and Mn3O4 nanoparticles within the MnCO3 compacts or hollowing of the microspheres during the compaction was observed. The direct production of microstructure-controlled compacts by HHP will contribute to new structural designs and add functionalities to existing applications.

关键词： Hydrothermal hot-pressing microstructural development Microspheres Hollowing Low-temperature sintering

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microstructural development and creep behavior in A286 superalloy

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MATERIALS CHARACTERIZATION 2004年第2期52卷 85-92页

作者： De Cicco, H Luppo, MI Gribaudo, LM Ovejero-García, J Comis Nacl Energia Atom Dept Mat Buenos Aires DF Argentina

The precipitation-hardened alloy A286 has been characterized as a function of ageing treatment, and the creep behavior has been studied in the temperature range of 600-700 degreesC and at 230-740 MPa. Microhardness tests of samples aged at different temperatures have been performed, and it was observed that the fastest precipitation kinetics of the metastable gamma occurred during ageing at 730 degreesC. Further exposure at this temperature degraded the good mechanical properties of the material because the gamma dissolved, and the stable eta phase formed. Optical and scanning and transmission electron microscopy (SEM and TEM, respectively) characterization of samples in as received state and after ageing were performed to study the microstructural development. In all creep tests, the damage observed was intergranular. The correlation between secondary strain rate and time to failure was shown to be a modified Monkman-Grant, including the elongation to rupture and an exponent different of 1 for the strain rate to obtain a better correlation. T he Larson-Miller parameter has been used to correlate creep stress, temperature and rupture time for the aged material. (C) 2004 Elsevier Inc. All rights reserved.

关键词： microstructural development creep behavior A286 superalloy

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microstructural development in Pt-aluminide coating on CMSX-4 superalloy during TMF

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SURFACE & COATINGS TECHNOLOGY 1998年第1期107卷 76-83页

作者： Zhang, YH Knowles, DM Withers, PJ Univ Cambridge Dept Mat Sci & Met Cambridge CB2 3QZ England

The microstructure and the microstructural development of a Pt-aluminide coating on CMSX-4 superalloy during thermal mechanical fatigue (TMF) over a temperature range from 300 to 1050 degrees C have been characterised. Two kinds of precipitates have been observed in the as-coated condition;submicron-sized tungsten structured particles in the outer layer of the coating and micron-sized mu phase in the inner layer of the coating. During TMF testing, the coating extended into the original substrate with the initial gamma/gamma' substrate, transforming to a mixture of gamma', beta-NiAl and a certain amount of mu-phase precipitates. beta-NiAl grains mostly exhibit a lath shape in this region. Another important microstructural change is the precipitation of many sigma-phase needles in the substrate adjacent to the interface with the coating. The microstructural changes became more evident as the number of TMF cycles increased. No detrimental effect on TMF lives in terms of crack initiation and growth from these TCP phases was found. The distribution of alloying elements in precipitates, beta-NiAl phase and substrate has been analysed, and their influence on the precipitation of some phases is discussed. (C) 1998 Elsevier Science S.A. All rights reserved.

关键词： CMSX-4 superalloy microstructural development Pt-aluminide coating TMF

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microstructural development in a rapidly cooled eutectic Sn-3.5% Ag solder reinforced with copper powder

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POWDER TECHNOLOGY 2006年第1期166卷 38-46页

作者： Lin, D. C. Srivatsan, T. S. Wang, G-X Kovacevic, R. Univ Akron Dept Engn Mech Div Mat Sci & Engn Akron OH 44325 USA So Methodist Univ Dept Engn Mech Res Ctr Adv Mfg Richardson TX 75081 USA

Experiments using eutectic Sn-3.5% Ag solder paste were conducted with the objective of examining the conjoint influence of copper particles addition and rapid cooling on microstructural development. The composite solder mixture was made by thoroughly mixing a pre-weighed amount of copper particles with a commercial Sn-3.5% Ag solder paste. The experiments were quite similar to the heating and cooling cycle of an industrial reflow soldering process. Heating of the samples was conducted in a furnace whose temperature was carefully controlled. The cooling process was conducted on a chilled aluminum block through which coolant was circulated at 0.5 degrees C. When the solder temperature reached 250 degrees C, the circulating system would turn on automatically and the sample, which is still molten, is forced to cool rapidly. Temperature records of the solder samples revealed that addition of copper particles to the eutectic Sn-3.5% Ag did not appreciably affect the heating and melting properties when compared to the unreinforced Sn-3.5% Ag counterpart. However, copper particles did change the solidification temperature of the composite solder. Detailed observations for varying amounts of copper particle addition revealed that copper particles less than 1.0 wt.% lowered the solidification temperature of the composite solder. For copper particles greater than 1.0 wt.%, the solidification temperature increased a few degrees Celsius, indicating that some of the copper particles did not completely dissolve in the Sn-dominant solder during the melting process. Results reveal that as-solidified microstructures of the eutectic Sn-3.5% Ag solder contain columnar type dendrites of the Sn-rich phase and a cutectic mixture of the Sn3Ag and Sn-rich phase located between the dendrite columns. The addition of copper particles to the eutectic Sn-3.5% Ag solder does refine the morphology of the primary phase, which is attributed to the presence and distribution of the Cu6Sn5 intermetall

关键词： microstructural development Sn-3.5% Ag alloy Cu6Sn5 intermetallic compound micro-sized Cu powder rapid cooling

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Thermal cycling of EB-PVD/MCrAlY thermal barrier coatings: 1. microstructural development and spallation mechanisms

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SURFACE & COATINGS TECHNOLOGY 2001年 146卷 70-78页

作者： Sohn, YH Kim, JH Jordan, EH Gell, M Univ Connecticut Dept Met & Mat Engn Storrs CT 06269 USA Univ Connecticut Dept Mech Engn Storrs CT 06269 USA

microstructural changes, damage initiation and spallation Of a production TBC, which consists of: an electron beam physical vapor deposited ZrO2-7 wt.% Y2O3 (YSZ);thermally grown oxide (TGO);MCrAlY bond coat;and a polycrystalline IN-738 superalloy substrate, were examined as a function of thermal cycles at 1121 degreesC. Thermal cycling for TBC specimens in air consisted of a 10-min heat-up, a 40-min hold at 1121 degreesC and a 10-min quench. microstructural characterization was carried out by: photo-stimulated luminescence piezo-spectroscopy (PLPS), X-ray diffraction (XRD). scanning electron microscopy (SEM);and energy dispersive spectroscopy (EDS). development of microstructure in the YSZ coatings, growth of the thermally grown oxide (TGO) and its constituents. and phase transformations in the MCrAlY bond coat were examined as a function of thermal cycles. Instability of the TGO/bond coat interface (i.e. rumpling), leading to localized cracking at the YSZ/TGO interface and within the YSZ, was observed after as few as five thermal cycles. Spallation of YSZ coatings occurred after approximately 400 cycles. Significant void formation at the TGO/bond coat interface and formation of a Ni/Co rich oxides at the TGO/bond coat interface due to rapid internal oxidation of Al-depleted MCrAlY bond coat were strong contributors to spallation failure of the TBC. The final spallation of TBC results from a 'link-up' of damage at the TGO/bond coat interface with the rumpling-induced micro-cracking at the YSZ/TGO interface. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词： thermal barrier coatings thermal cyclic oxidation failure mechanisms electron beam physical vapor deposition microstructural development scanning electron microscopy

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Microchemical analysis and microstructural development of Cr-doped mullites

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MICROCHIMICA ACTA 2004年第1-4期145卷 255-260页

作者： Villar, MP Geraldía, JM Molina, SI García, R Univ Cadiz Dpto Ciencia Mat & Ingn Met & Quim Inorgan E-11510 Puerto Real Cadiz Spain Univ Cadiz SCCYT Div Microscopia Elect E-11510 Puerto Real Cadiz Spain

A characterization study of chromium doped sol-gel mullites (with Cr2O3 contents varying between 1 and 9 wt.%) by means of electron beam techniques is presented. Scanning and transmission electron microscopy studies gave information about general microstructural features, like grain size and shape, presence of glassy phase in triple grain junctions and segregation of secondary crystalline phases. EDX-TEM measurements reveal an upper solubility of chromium in the mullite lattice of approx. 8 wt.% Cr2O3. The effect of Cr doping in the microstructural development of these mullites is discussed.

关键词： chromium mullite aluminosilicate microstructural development transition metal doping

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Microchemical analysis and microstructural development of Cr-doped mullites

Microchemical analysis and microstructural development of Cr...

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8th Workshop of the European-Microbeam-Analysis-Society

关键词： chromium mullite aluminosilicate microstructural development transition metal doping

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Densification and microstructural development during the firing of compounds in the Si₃N₄-SiO₂-Y₂O₃ system

Densification and microstructural development during the fir...

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8th Conference of the European-Ceramic-Society

作者： Itatani, K Okamoto, M Okada, I Sophia Univ Fac Sci & Engn Dept Chem Chiyoda Ku Tokyo 1028554 Japan

ISBN: (纸本)0878499466

Among the compounds in the Si3N4-SiO2-Y2O3 System, we examined densification/microstructural development during the firing of the melilite phase (Y2Si3O3N4), and evaluated the mechanical strength (Vickers hardness) and heat resistance of the resulting ceramic. Relative densities Of Y2Si3O3N4 compacts fired at 1800degreesC for 4 h or more were as high as 95%. The Vickers hardness of the dense melilite ceramic was approximately 15 GPa. The oxidation of the melilite ceramic in air was inhibited below 1200degreesC, due to the formation of an oxide layer on the surface.

关键词： oxynitride ceramics in the Si-3-N4SiO2-Y2O3 system melilite (Y2Si3O3N4) densification microstructural development

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Mechanical Behaviour and Induced microstructural development upon Simultaneous and Balanced Biaxial Stretching of Poly(ethylene furandicarboxylate), PEF

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POLYMERS 2023年第3期15卷

作者： Forestier, Emilie Combeaud, Christelle Guigo, Nathanael Sbirrazzuoli, Nicolas PSL Univ Ctr Mat Forming CEMEF Mines Paris UMR CNRS 7635 F-06904 Sophia Antipolis France Univ Cote Azur Inst Chim Nice ICN CNRS UMR7272 F-06108 Nice 2 France

The biaxial behavior of PEF has been analyzed for equilibrated and simultaneous biaxial stretching. The ability of PEF to develop an organized microstructure through strain induced crystallization (SIC) has been described. Upon biaxial stretching, SIC can be difficult to perform because the stretching is performed in two perpendicular directions. However, thanks to the time/temperature superposition principle and an accurate heating protocol, relevant stretching settings have been chosen to stretch the material in its rubbery-like state and to reach high levels of deformation. By the protocol applied, the mechanical behavior is easily transposable to the industry. This work has shown that PEF can, as in uniaxial stretching, develop well-organized crystals and a defined microstructure upon biaxial stretching. This microstructure allows the obtention of improved mechanical properties and thermal stability of the biaxially stretched samples. The crystals induced upon biaxial stretching are similar to the one that has been developed and observed after uniaxial stretching and upon static crystallization. Moreover, the furan cycles seem to appear in a state similar to the one of a sample crystallized upon quiescent condition. The rigidity is increased, and the alpha-relaxation temperature is increased by 15 degrees C.

关键词： Polyethylene 2 5-furandicarboxylate biaxial stretching microstructural development strain-induced crystallization (SIC)

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