The Experts below are selected from a list of 39546 Experts worldwide ranked by ideXlab platform
Christian Coddet - One of the best experts on this subject based on the ideXlab platform.
-
in situ tib near α ti matrix composites manufactured by selective Laser melting
Additive manufacturing, 2016Co-Authors: Nan Kang, Han Lin Liao, Pierre Coddet, Qi Liu, Christian CoddetAbstract:Abstract TiB reinforced near α Ti-matrix composite was fabricated in this work using selective Laser melting from a mixture of CrB 2 and commercially pure Ti powders. The corresponding composites present an almost fully dense structure for suitable Laser Energy Density conditions. The X-ray diffraction and microstructure analysis indicate that the TiB and β-Ti phase appears for parts obtained with a low scanning speed of the Laser beam. The parts obtained at high and low scanning speeds show higher hardness and lower wear rate than those obtained for intermediate scanning speed which, on the contrary, show the highest Density. The wear behavior of the as-processed parts is compared with that of pure Ti parts also obtained by selective Laser melting.
-
effects of processing parameters on properties of selective Laser melting mg 9 al powder mixture
Materials & Design, 2012Co-Authors: Han Lin Liao, Christian CoddetAbstract:Abstract In the present study, selective Laser melting (SLM) was used to sinter a powder mixture of Mg–9%Al. Both densification mechanism and microstructure evolution of Laser sintered powder mixture were established. The effect of Laser processing parameter on Mg–9%Al powder using SLM was also investigated. It can be found that a maximum relative Density was 82% with preferable process parameters of v = 0.02 m/s, P = 15 W. An overlapped structure can be obtained when decreasing the Laser Energy Density due to an incomplete melt. On the other hand, a severe particulate agglomeration appeared as the increase of the Laser Energy due to a balling effect. A critical scanning speed of 0.02 m/s can ensure that the particulates were well melted and not evaporated during the experiment. Moreover, the Mg and Al elements were dispersed uniformly in the samples. The microstructure and composition phase were studied through scanning electron microscopy (SEM) and X-ray elemental mapping (XRD) respectively.
-
effects of processing parameters on properties of selective Laser melting mg 9 al powder mixture
Materials & Design, 2012Co-Authors: Baicheng Zhang, Han Lin Liao, Christian CoddetAbstract:Abstract In the present study, selective Laser melting (SLM) was used to sinter a powder mixture of Mg–9%Al. Both densification mechanism and microstructure evolution of Laser sintered powder mixture were established. The effect of Laser processing parameter on Mg–9%Al powder using SLM was also investigated. It can be found that a maximum relative Density was 82% with preferable process parameters of v = 0.02 m/s, P = 15 W. An overlapped structure can be obtained when decreasing the Laser Energy Density due to an incomplete melt. On the other hand, a severe particulate agglomeration appeared as the increase of the Laser Energy due to a balling effect. A critical scanning speed of 0.02 m/s can ensure that the particulates were well melted and not evaporated during the experiment. Moreover, the Mg and Al elements were dispersed uniformly in the samples. The microstructure and composition phase were studied through scanning electron microscopy (SEM) and X-ray elemental mapping (XRD) respectively.
-
modification of ceramic thermal spray deposit microstructures implementing in situ Laser remelting
Surface & Coatings Technology, 2003Co-Authors: Guy Antou, Françoise Hlawka, Ghislain Montavon, Alain Cornet, Christian Coddet, Frédérique MachiAbstract:Abstract Yttria partially stabilized zirconia thermal barrier coatings (TBCs) are widely used to protect components of gas turbines against deterioration at high temperatures. Air plasma spray and Laser irradiation processes are combined to improve properties of TBCs. An in situ Laser remelting plasma-spraying technique, implementing in particular a diode Laser, was performed. Results show that Laser treatment may induce: (1) no phase transition: the metastable tetragonal phase still remains the predominant phase after Laser treatment; (2) a decrease of the pore network connectivity level for a Laser Energy Density ranging from 1.7 to 1.9 J mm −2 ; (3) the growth of fine dendritic structures (due to the rapid solidification), which could be interesting with regard to the improvement of the thermo-mechanical properties of the coating.
Han Lin Liao - One of the best experts on this subject based on the ideXlab platform.
-
in situ tib near α ti matrix composites manufactured by selective Laser melting
Additive manufacturing, 2016Co-Authors: Nan Kang, Han Lin Liao, Pierre Coddet, Qi Liu, Christian CoddetAbstract:Abstract TiB reinforced near α Ti-matrix composite was fabricated in this work using selective Laser melting from a mixture of CrB 2 and commercially pure Ti powders. The corresponding composites present an almost fully dense structure for suitable Laser Energy Density conditions. The X-ray diffraction and microstructure analysis indicate that the TiB and β-Ti phase appears for parts obtained with a low scanning speed of the Laser beam. The parts obtained at high and low scanning speeds show higher hardness and lower wear rate than those obtained for intermediate scanning speed which, on the contrary, show the highest Density. The wear behavior of the as-processed parts is compared with that of pure Ti parts also obtained by selective Laser melting.
-
effects of processing parameters on properties of selective Laser melting mg 9 al powder mixture
Materials & Design, 2012Co-Authors: Han Lin Liao, Christian CoddetAbstract:Abstract In the present study, selective Laser melting (SLM) was used to sinter a powder mixture of Mg–9%Al. Both densification mechanism and microstructure evolution of Laser sintered powder mixture were established. The effect of Laser processing parameter on Mg–9%Al powder using SLM was also investigated. It can be found that a maximum relative Density was 82% with preferable process parameters of v = 0.02 m/s, P = 15 W. An overlapped structure can be obtained when decreasing the Laser Energy Density due to an incomplete melt. On the other hand, a severe particulate agglomeration appeared as the increase of the Laser Energy due to a balling effect. A critical scanning speed of 0.02 m/s can ensure that the particulates were well melted and not evaporated during the experiment. Moreover, the Mg and Al elements were dispersed uniformly in the samples. The microstructure and composition phase were studied through scanning electron microscopy (SEM) and X-ray elemental mapping (XRD) respectively.
-
effects of processing parameters on properties of selective Laser melting mg 9 al powder mixture
Materials & Design, 2012Co-Authors: Baicheng Zhang, Han Lin Liao, Christian CoddetAbstract:Abstract In the present study, selective Laser melting (SLM) was used to sinter a powder mixture of Mg–9%Al. Both densification mechanism and microstructure evolution of Laser sintered powder mixture were established. The effect of Laser processing parameter on Mg–9%Al powder using SLM was also investigated. It can be found that a maximum relative Density was 82% with preferable process parameters of v = 0.02 m/s, P = 15 W. An overlapped structure can be obtained when decreasing the Laser Energy Density due to an incomplete melt. On the other hand, a severe particulate agglomeration appeared as the increase of the Laser Energy due to a balling effect. A critical scanning speed of 0.02 m/s can ensure that the particulates were well melted and not evaporated during the experiment. Moreover, the Mg and Al elements were dispersed uniformly in the samples. The microstructure and composition phase were studied through scanning electron microscopy (SEM) and X-ray elemental mapping (XRD) respectively.
Dongdong Gu - One of the best experts on this subject based on the ideXlab platform.
-
selective Laser melting additive manufactured inconel 718 superalloy parts high temperature oxidation property and its mechanisms
Optics and Laser Technology, 2014Co-Authors: Dongdong GuAbstract:Abstract This work presented a comprehensive study of high-temperature oxidation behaviors and mechanisms of Selective Laser melting (SLM) processed Inconel 718 superalloy parts using different methods including isothermal oxidation testing, X-ray diffraction, scanning electron microscopy and Energy dispersive X-ray spectroscopy. The experimental results revealed that the oxidation process of the tested parts processed at a lower volumetric Laser Energy Density experienced the severe spallation. On reasonably increasing the applied volumetric Laser Energy Density, the oxidation kinetics of the as-produced parts obeyed a parabolic law, exhibiting the significantly improved oxidation resistance performance. The constitutional phases within the oxidation film were identified and the corresponding formation mechanisms were elucidated in detail according to the thermodynamic principles. The cross-sectional morphologies of oxidized Inconel 718 parts indicated that the oxidation microstructure mainly consisted of an external oxidation layer and an internal oxidation zone. The oxidation process was controlled by the outward diffusion of oxide forming elements and inward penetration of oxygen, by which the interaction mechanisms between the microstructures and internal oxidation zones were clarified. On the basis of the experimental results and theoretical analyses, the physical oxidation mechanisms were accordingly established to illustrate the oxidation behaviors of SLM-processed Inconel 718 parts at elevated operative temperatures.
-
selective Laser melting additive manufacturing of inconel 718 superalloy parts densification microstructure and properties
Journal of Alloys and Compounds, 2014Co-Authors: Dongdong GuAbstract:Abstract This paper presented a comprehensive study of densification behavior, microstructural features, microhardness, wear performance and high-temperature oxidation properties of Inconel 718 parts fabricated by selective Laser melting (SLM), a typical additive manufacturing process. The relationship of processing conditions, microstructures and material properties was established. The occurrence of balling phenomenon at a lower Laser Energy Density input reduced the relative Density of the formed parts. A reasonable increase in Laser Energy Density yielded a near-full densification. The typical microstructures of SLM-processed Inconel 718 parts experienced successive morphological changes on increasing the applied Laser Energy Density: coarsened columnar dendrites – clustered dendrites – slender and uniformly distributed columnar dendrites. The optimally prepared fully dense Inconel 718 parts had a uniform microhardness distribution with a mean value of 395.8 HV 0.2 , a considerably low friction coefficient of 0.36 and a reduced wear rate of 4.64 × 10 −4 mm 3 /N m in sliding wear tests. The formation of an adherent tribolayer on the worn surface contributed to the improvement of wear performance. The high-temperature oxidation resistance was enhanced as the applied Laser Energy Density increased and the elevated high-temperature oxidation property was primarily attributed to the formation of refined microstructural architectures of SLM-processed parts.
-
Selective Laser Melting Additive Manufacturing of Ti-Based Nanocomposites: The Role of Nanopowder
Metallurgical and Materials Transactions A, 2014Co-Authors: Dongdong Gu, Hongqiao Wang, Guoquan ZhangAbstract:The additive manufacturing of bulk-form TiC/Ti nanocomposite parts was performed using Selective Laser Melting (SLM). Two categories of nanopowder, i.e., ball-milled TiC/Ti nanocomposite powder and directly mechanical mixed nano-TiC/Ti powder, were used for SLM. The influences of nanopowder characteristics and Laser processing parameters on the densification behavior, microstructural features, and tribological properties of the SLM-processed TiC/Ti nanocomposite parts were studied. The study showed that the densification of TiC/Ti nanocomposite parts was affected by both Laser Energy Density and powder categories. Using an insufficient Laser Energy Density of 0.25 kJ/m lowered SLM densification rate, because of the occurrence of balling effect. An increase in the Laser Energy Density above 0.33 kJ/m produced near fully dense SLM parts. The SLM densification levels of the ball-milled TiC/Ti nanocomposite powder were generally higher than that of the directly mixed nano-TiC/Ti powder. The TiC-reinforcing phase in SLM-processed TiC/Ti parts typically had a lamellar nanostructure with a nanoscale thickness, completely differing from the starting nanoparticle morphology before SLM. The lamellar nanostructure of the TiC reinforcement in SLM-processed ball-milled TiC/Ti nanocomposite parts could be maintained within a wide range of Laser Energy densities. However, the microstructures of the SLM-processed, directly mixed nano-TiC/Ti powder were sensitive to SLM parameters, and the TiC reinforcement experienced a successive change from the lamellar nanostructure to the relatively coarsened dendritic microstructure as Laser Energy Density increased. A combination of the sufficiently high SLM densification rate and the formation of the nanostructured TiC reinforcement favored the improvement of the tribological property, leading to the considerably low coefficient of friction of 0.22 and wear rate of 2.8 × 10−16 m3 N−1 m−1. The coarsening and resultant disappearance of nanoscale TiC reinforcement in SLM-consolidated directly mixed nano-TiC/Ti powder at a high Laser Energy Density lowered the tribological performance considerably.
-
selective Laser melting additive manufacturing of tic alsi10mg bulk form nanocomposites with tailored microstructures and properties
Physics Procedia, 2014Co-Authors: Dongdong Gu, Hongqiao Wang, Yveschristian Hagedorn, Fei Chang, Pengpeng Yuan, Wilhelm MeinersAbstract:Abstract The nanoscale TiC particle reinforced AlSi10Mg nanocomposite parts were produced by selective Laser melting (SLM) additive manufacturing process. The influence of Laser Energy Density (LED) on densification behavior, microstructural evolution, microhardness and wear properties of SLM-processed TiC/AlSi10Mg nanocomposites was studied. It showed that the near fully dense nanocomposite parts (>98% theoretical Density) were achieved with increasing the applied LED. The TiC reinforcement in SLM-processed parts experienced a microstructural change from the standard nanoscale particle morphology (the average size 77-93 nm) to the relatively coarsened submicron structure (the mean particle size 154 nm) as the LED increased.The sufficiently high densification rate combined with the homogeneousdistribution of nanoscale TiC reinforcement throughout the matrix led to a high microhardness of 181.2 HV0.2, a considerably low coefficient of friction (COF) of 0.36, and a reduced wear rate of 2.94×10-5 mm3N-1m-1 for SLM-processed TiC/AlSi10Mg nanocomposite parts.
-
Densification, Microstructure, and Wear Property of In Situ Titanium Nitride-Reinforced Titanium Silicide Matrix Composites Prepared by a Novel Selective Laser Melting Process
Metallurgical and Materials Transactions A, 2012Co-Authors: Dongdong Gu, Chen Hong, Guangbin MengAbstract:This work presents the densification behavior, microstructural features, microhardness, and wear property of in situ TiN/Ti5Si3 composite parts prepared by a novel Selective Laser Melting (SLM) process. The occurrence of balling phenomenon at a low Laser Energy Density combined with a high scan speed and the formation of thermal cracks at an excessive Laser Energy input generally decreased densification rate. The in situ-formed TiN reinforcing phase experienced a successive morphological change: an irregular polyangular shape—a refined near-round shape—a coarsened dendritic shape, as the applied Laser Energy Density increased. The variations in liquid-solid wettability and intensity of Marangoni convection within Laser molten pool accounted for the different growth mechanisms of TiN reinforcement. The TiN/Ti5Si3 composite parts prepared under the optimal SLM conditions had a near-full 97.7 pct theoretical Density and a uniform microhardness distribution with a significantly increased average value of 1358.0HV0.3. The dry sliding wear tests revealed that a considerably low friction coefficient of 0.19 without any apparent fluctuation and a reduced wear rate of 6.84 × 10−5mm3/Nm were achieved. The enhanced wear resistance was attributed to the formation of adherent strain-hardened tribolayer covered on the worn surface.
Baicheng Zhang - One of the best experts on this subject based on the ideXlab platform.
-
microhardness and microstructure evolution of tib2 reinforced inconel 625 tib2 composite produced by selective Laser melting
Optics and Laser Technology, 2016Co-Authors: Baicheng Zhang, Guijun BiAbstract:Abstract In this study, micron-size TiB 2 particles were utilized to reinforce Inconel 625 produced by selective Laser melting. Exceptional microhardness 600–700 HV 0.3 of the composite was obtained. In further investigation, the microstructure and mechanical properties of Inconel 625/TiB 2 composite can be significantly influenced by addition of TiB 2 particles during SLM. It was found that the long directional columnar grains observed from SLM-processed Inconel 625 were totally changed to fine dendritic matrix due to the addition of TiB 2 particles. Moreover, with Laser Energy Density (LED) of 1200 J/m, a Ti, Mo rich interface around TiB 2 particles with fine thickness can be observed by FESEM and EDS. The microstructure evolution can be determined by different Laser Energy Density (LED): under 1200 J/m, γ phase in dendrite grains; under 600 J/m, γ phase in combination of dendritic and acicular grains; under 400 J/m, γ phase acicular grains. Under optimized LED 1200 J/m, the dynamic nanohardness (8.62 GPa) and elastic modulus (167 GPa) of SLM-processed Inconel 625/TiB 2 composite are higher compared with those of SLM-processed Inconel 625 (3.97 GPa and 135 GPa, respectively).
-
effects of processing parameters on properties of selective Laser melting mg 9 al powder mixture
Materials & Design, 2012Co-Authors: Baicheng Zhang, Han Lin Liao, Christian CoddetAbstract:Abstract In the present study, selective Laser melting (SLM) was used to sinter a powder mixture of Mg–9%Al. Both densification mechanism and microstructure evolution of Laser sintered powder mixture were established. The effect of Laser processing parameter on Mg–9%Al powder using SLM was also investigated. It can be found that a maximum relative Density was 82% with preferable process parameters of v = 0.02 m/s, P = 15 W. An overlapped structure can be obtained when decreasing the Laser Energy Density due to an incomplete melt. On the other hand, a severe particulate agglomeration appeared as the increase of the Laser Energy due to a balling effect. A critical scanning speed of 0.02 m/s can ensure that the particulates were well melted and not evaporated during the experiment. Moreover, the Mg and Al elements were dispersed uniformly in the samples. The microstructure and composition phase were studied through scanning electron microscopy (SEM) and X-ray elemental mapping (XRD) respectively.
Xiaoyan Zeng - One of the best experts on this subject based on the ideXlab platform.
-
effect of crystallographic orientation on mechanical anisotropy of selective Laser melted ti 6al 4v alloy
Materials Characterization, 2017Co-Authors: Jingjing Yang, Zemin Wang, Xiaoyan ZengAbstract:Abstract The crystallographic texture of Ti-6Al-4V produced by selective Laser melting (SLM) under various Laser Energy densities was characterized by electron backscatter diffraction technique to explore its effect on the anisotropy in tensile properties. Results show that crystallographic orientation depending on Laser Energy Density acts a significant role in determining the mechanical anisotropy of SLMed Ti-6Al-4V samples. The microstructure of the SLMed Ti-6Al-4V samples consists of fully martensites. As for the martensites, the fraction of basal orientations decreases, while the content of prismatic orientations increases with Laser Energy Density increasing from 101 to 269 J/mm3. And the order of the dominated crystallographic orientation of martensites with the Laser Energy Density is (12 3 − 0)[2 1 − 1 − 3] → (11 2 ¯ 4)[ 1 − 3 − 41] → (11 2 − 0)[1 1 − 01] → (11 2 − 0)[2 2 − 03]. There is anisotropy in tensile properties between horizontally and vertically built samples, which is more obvious with Laser Energy Density. The formation of such anisotropy is ascribed to the higher Schmid factor values of the grains in the vertically built tensile samples than those in horizontally built ones.
-
selective Laser melting of high strength al cu mg alloys processing microstructure and mechanical properties
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Hu Zhang, Haihong Zhu, Ting Qi, Zhiheng Hu, Xiaoyan ZengAbstract:Abstract The interest for a wider range of usable materials for the technology of selective Laser melting (SLM) is growing. In this work, the manufacturing of wrought Al–Cu–Mg parts using SLM technology was systematically investigated. The effect of processing parameters on the Density of the deposited Al–Cu–Mg samples was studied. It shows that the Laser Energy Density plays a significant role in the densification behavior of the Al–Cu–Mg powder during the SLM process. The Laser Energy Density value of 340 J/mm 3 is found to be the threshold, above which high Density samples (99.8%) without imperfections and microcracks can be obtained. The SLMed Al–Cu–Mg part presents a unique layer-wise feature which consisted of an extremely fine supersaturated cellular-dendrites structure. The ultimate tensile strength of 402 MPa and the yield strength of 276 MPa are achieved for the SLMed Al–Cu–Mg part. The combination of grain refinement and solid solution strengthening mechanisms during SLM process are proposed to explain the high mechanical strength.
