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Improvement of Surface Mechanical and Tribological Characteristics of L-PBF Processed Commercially Pure Titanium through Ultrasonic Impact Treatment

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Acta Metallurgica Sinica(English Letters) 2024年第6期37卷 1034-1046页

作者： Iman Ansarian Reza Taghiabadi Saeid Amini Mohammad Hossein Mosallanejad Luca Iuliano abdollah saboori Department of Materials Science and Metallurgy Imam Khomeini International University(IKIU)QazvinIran Department of Mechanical Engineering University of KashanKashanIran Integrated Additive Manufacturing Center Department of Management and Production EngineeringPolitecnico di TorinoCorso Duca Degli Abruzzi 2410129TurinItaly

Multi-pass ultrasonic impact treatment(UIT)was applied to modify the microstructure and improve the mechanical and tribological characteristics at the near-surface region of commercially pure Ti(CP-Ti)specimens produced by the laser powder bed fusion(L-PBF)*** considerably refined the L-PBF process-related acicular martensites(α′-M)and produced a well-homogenized and dense surface microstructure,where the porosity content of 1-,3-,and 5-pass UITed samples was reduced by 43,60,and 67%,*** UITed samples showed an enhancement in their near-surface mechanical properties up to a depth of about 300μ*** nanoindentation results for the 3-pass UITed sample revealed an increase of about 53,45,and 220%in its nanohardness,H/E_(r),and H_(3)/E_(r)^(2)indices,*** stylus profilometry results showed that performing the UIT removed the L-PBF-related features/defects and offered a smooth *** roughness average(R_(a))and the skewness(R_(sk))of the 3-pass UITed sample were found to be lower than those of the L-PBFed sample by 95 and 223%,*** the UIT also enhanced the material ratio,where the maximum load-bearing capacity(~100%)in as-L-PBFed(as-built)and 3-pass UITed samples was obtained at 60-and 10-µm depths,*** tribological investigations showed that applying the UIT resulted in a significant reduction of wear rate and average coefficient of friction(COF)of *** instance,under the normal pressures of 0.05 and 0.2 MPa,the wear rate and COF of the 3-pass UITed sample were lower than those of the L-PBFed sample by 65 and 58%,and 20 and 17%,respectively.

关键词： Laser powder bed fusion Ultrasonic impact treatment Commercially pure Ti(CP-Ti) Surface mechanical properties Tribological properties

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Reactive spontaneous infiltration of Al-activated TiO_2 by molten aluminum

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Transactions of Nonferrous Metals Society of China 2019年第3期29卷 657-666页

作者： abdollah saboori Xiang CHEN Claudio BADINI Paolo FINO Matteo PAVESE Department of Applied Science and Technology Politecnico di TorinoCorso Duca Degli Abruzzi 24 10129 Torino Italy Research Center of Graphene Applications Beijing Institute of Aeronautical Materials Beijing 100095 China

The reactive spontaneous infiltration of Al-activated TiO2 (anatase) was investigated. Pure Al powder was blended with TiO2 for activation. They were compacted into the preform and then sealed within 6060 alloy mould. The activation and infiltration were carried out in 6060 alloy bath for 1 h and comparative sintering experiments were carried out in an argon protected environment under the same conditions of temperature and duration. X-ray diffraction analysis proved that the Al sealed environment was superior to the argon protection on activating the reaction between Al and TiO2. The blending ratio of TiO2 to Al and the temperature were found to play the most important role in infiltration by affecting infiltration and reaction kinetics. Three main types of microstructures were observed after infiltration: full infiltration, partial infiltration with the formation of cracks and no infiltration. The formation of these microstructures was explained on the basis of reaction kinetics and local volume changes due to the reactions. Ultimately, it is found that to obtain an overall good spontaneous infiltration, a TiO2 to Al blending ratio around 3:7 in volume and an infiltration temperature around 900 °C are the most suitable.

关键词： spontaneous infiltration pressureless sintering TiO2-Al reaction infiltration kinetics in-situ fabrication

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Microstructure and Thermal Conductivity of Al–Graphene Composites Fabricated by Powder Metallurgy and Hot Rolling Techniques

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Acta Metallurgica Sinica(English Letters) 2017年第7期30卷 675-687页

作者： abdollah saboori Matteo Pavese Claudio Badini Paolo Fino Department of Applied Science and Technology Politecnico di Torino Corso Duca degli Abruzzi 24 10129 Turin Italy

The objective of this research is to improve the thermal conductivity and mechanical properties of Al/GNPs（graphene nanoplatelets） nanocomposites produced by classical powder metallurgy and hot rolling techniques. The microstructural evaluation confirmed the uniform dispersion of GNPs at low content and agglomeration at higher contents of GNPs. The structure of graphene was studied before and after the mixing and the Raman spectrum proofs that the wet mixing has a great potential to be used as a dispersion method. There was no significant peak corresponding to the Al_4C_3 formation in both the differential scanning calorimetry curves and X-ray diffraction patterns. The microstructural observation in both fabrication techniques showed grain refinement as a function of the GNPs content. Moreover, the introduction of the GNPs not only improved the Vickers hardness of the composites but also decreased their density. The thermal conductivity investigations showed that in both the press-sintered and hot-rolled samples, although the thermal conductivity of composites was improved at low GNPs contents, it was negatively affected at high GNPs contents.

关键词： Aluminum Graphene Thermal conductivity Powder metallurgy Microstructure

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A Novel Cu–GNPs Nanocomposite with Improved Thermal and Mechanical Properties

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Acta Metallurgica Sinica(English Letters) 2018年第2期31卷 148-152页

作者： abdollah saboori Matteo Pavese Claudio Badini Paolo Fino Department of Applied Science and Technology Politecnico di Torino

Classical powder metallurgy followed by either hot isostatic pressing（HIPing） or repressing–annealing process was used to produce Cu–graphene nanoplatelets（GNPs） nanocomposites in this work. A wet mixing method was used to disperse the graphene within the matrix. The results show that a uniform dispersion of GNPs at low graphene contents could be achieved, whereas agglomeration of graphene was revealed at higher graphene contents. Density evaluations showed that the relative density of pure copper and copper composites increased by using the post-processing ***, it should be noticed that the efficiency of HIPing was remarkably higher than repressing–annealing process, and through the HIPing, fully dense samples were achieved. The Vickers hardness results showed that the reconsolidation steps can improve the mechanical strength of the specimens up to 50% owing to the progressive porosity elimination after reconsolidation. The thermal conductivity results of pure copper and composites at high temperatures showed that the postprocessing techniques could enhance the conductivity of materials significantly.

关键词： Copper Graphene nanoplatelets (GNPs) Powder metallurgy Hot isostatic pressing Thermal conductivity

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A Comprehensive Overview on the Latest Progress in the Additive Manufacturing of Metal Matrix Composites: Potential, Challenges, and Feasible Solutions

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Acta Metallurgica Sinica(English Letters) 2021年第9期34卷 1173-1200页

作者： Mehran Dadkhah Mohammad Hossein Mosallanejad Luca Iuliano abdollah saboori Department of Applied Science and Technology Politecnico di TorinoCorso Duca Degli Abruzzi 2410129 TorinoItaly Department of Materials Engineering Isfahan University of Technology84156-83111 IsfahanIran Department of Management and Production Engineering Politecnico di TorinoCorso Duca Degli Abruzzi 2410129 TorinoItaly

Nowadays, as an emerging technology, additive manufacturing(AM) has received numerous attentions from researchers around the world. The method comprises layer-by-layer manufacturing of products according to the 3D CAD models of the objects. Among other things, AM is capable of producing metal matrix composites(MMCs). Hence, plenty of works in the literature are dedicated to developing different types of MMCs through AM processes. Hence, this paper provides a comprehensive overview on the latest research that has been carried out on the development of the powder-based AM manufactured MMCs from a scientific and technological viewpoint, aimed at highlighting the opportunities and challenges of this innovative manufacturing process. For instance, it is documented that AM is not only able to resolve the reinforcement/matrix bonding issues usually faced with during conventional manufacturing of MMCs, but also it is capable of producing functionally graded composites and geometrically complex objects. Furthermore, it provides the opportunity for a uniform distribution of the reinforcing phase in the metallic matrix and is able to produce composites using refractory metals thanks to the local heat source employed in the method. Despite the aforementioned advantages, there are still some challenges needing more attention from the researchers. Rapid cooling nature of the process, significantly different coe fficient of expansion of the matrix and reinforcement, processability, and the lack of suitable parameters and standards for the production of defect-free AM MMCs seem to be among the most important issues to deal with in future works.

关键词： Additive manufacturing Metal matrix composite Microstructure Interfacial bonding Mechanical properties

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Development of AI-and Cu-based nanocomposites reinforced by graphene nanoplatelets： Fabrication and characterization

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Frontiers of Materials Science 2017年第2期11卷 171-181页

作者： abdollah saboori Matteo PAVESE Claudio BADINI Paolo FINO Department of Applied Science and Technology Politecnico Di Torino Corso Duca Degli Abruzzi 24 10129 Torino Italy

Aluminum and copper matrix nanocomposites reinforced by graphene nanoplatelets （GNPs） were successfully fabricated by a wet mixing method followed by conventional powder metallurgy. The uniform dispersion of GNPs within the metal matrices showed that the wet mixing method has a great potential to be used as a mixing technique. However, by increasing the GNPs content, GNPs agglomeration was more visible. DSC and XRD of AI/GNPs nanocomposites showed that no new phase formed below the melting point of AI. Microstructural observations in both nanocomposites reveal the evident grain refinement effect as a consequence of GNPs addition. The interfacial bonding evaluation shows a poor interfacial bonding between GNPs and AI, while the interfacial bonding between Cu and GNPs is strong enough to improve the properties of the Cu/GNPs nanocomposites. In both composites, the coefficient of thermal expansion decreases as a function of GNPs while, their hardness is improved by increasing the GNPs content as well as their elastic modulus.

关键词： nanocomposite aluminum copper graphene microstructure thermal expansion

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Microstructure and Mechanical Performance of Ti-6Al-4V Lattice Structures Manufactured via Electron Beam Melting(EBM):A Review

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Acta Metallurgica Sinica(English Letters) 2020年第2期33卷 183-203页

作者： Giuseppe Del Guercio Manuela Galati abdollah saboori Paolo Fino Luca Iuliano Department of Management and Production Engineering(DIGEP) Politecnico di TorinoCorso Duca Degli Abruzzi 2410129 TurinItaly Department of Applied Science and Technology(DISAT) Politecnico di TorinoCorso Duca Degli Abruzzi 2410129 TurinItaly Integrated Additive Manufacturing Center(IAM)@Polito Politecnico Di TorinoCorso Duca Degli Abruzzi 2410129 TurinItaly

Electron beam melting(EBM) process is an additive manufacturing process largely used to produce complex metallic components made of high-performance materials for aerospace and medical ***,lattice structures made by Ti-6A1-4V have represented a hot topic for the industrial sectors because of having a great potential to combine lower weights and higher performances that can also be tailored by subsequent heat ***,the little knowledge about the mechanical behaviour of the lattice structures is limiting their *** present work aims to provide a comprehensive review of the studies on the mechanical behaviour of the lattice structures made of *** main steps to produce an EBM part were considered as guidelines to review the literature on the lattice performance:(1) design,(2) process and(3) post-heat ***,the correlation between the geometrical features of the lattice structure and their mechanical behaviour is *** addition,the correlation among the mechanical performance of the lattice structures and the process precision,surface roughness and working temperature are also *** investigation on the studies about the properties of heat-treated lattice structure is also conducted.

关键词： Electron beam melting(EBM) Additive manufacturing(AM) Lattice structures Ti–6Al–4V Mechanical properties Heat treatment

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Microstructure and Corrosion Properties of CP-Ti Processed by Laser Powder Bed Fusion under Similar Energy Densities

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Acta Metallurgica Sinica(English Letters) 2022年第9期35卷 1453-1464页

作者： Mohammad Hossein Mosallanejad Saber Sanaei Masoud Atapour Behzad Niroumand Luca Iuliano abdollah saboori Department of Materials Engineering Isfahan University of Technology84156-83111IsfahanIran Department of Applied Science and Technology Politecnico di TorinoCorso Duca Degli Abruzzi 2410129TorinoItaly Department of Management and Production Engineering Politecnico di TorinoCorso Duca Degli Abruzzi 2410129TorinoItaly

In this work, two types of CP Ti cubes with similar volumetric energy densities(VED) but diff erent process parameters were produced using laser powder bed fusion(LPBF) method. The corrosion behavior of the fabricated specimens was investigated by conducting electrochemical impedance spectroscopy(EIS) and polarization experiments in simulated body fl uid(SBF) solution at 37 °C. The results indicated that the microstructure and porosities, which are of great importance for biomedical applications, can be controlled by changing the process parameters even under constant energy densities. The sample produced with a lower laser power(E1) was featured with a higher level of porosity and thinner alpha laths, as compared with the sample fabricated with a higher laser power(E2). Moreover, results obtained from the bioactivity tests revealed that the sample produced with a higher laser power conferred a slight improvement in the bioactivity due to the higher amount of porosity. Lower laser power and hence higher porosity level promoted the formation of bone-like apatite on the surface of the printed specimens. The potentiodynamic polarization tests revealed inferior corrosion resistance for the fabricated sample with higher porosity. Moreover, the EIS results after diff erent immersion times indicated that a stable oxide film was formed on the surface of samples for all immersion times. After 1 and 3 days of immersion, superior passivation behavior was observed for the sample fabricated with lower laser power. However, very similar impedance and phase values were observed for all the samples after 14 days of immersion.

关键词： Additive manufacturing Laser powder bed fusion Energy density Corrosion Microstructure CP Titanium

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Tribological behaviour of AZ31 magnesium alloy reinforced by bimodal size B_(4)C after precipitation hardening

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Journal of Magnesium and Alloys 2022年第11期10卷 3267-3280页

作者： Seyed Kiomars Moheimani Azadeh Keshtgar Saeed Khademzadeh Morteza Tayebi Ali Rajaee abdollah saboori Advanced Materials Research Center Department of Materials EngineeringNajafabad BranchIslamic Azad UniversityNajafabadIran Department of Research and Development Nejat Darya CompanyBoushehrIran Center for Risk and Reliability University of MarylandCollege ParkMD 20742United States Department of Industrial Engineering University of Padova35131 PadovaItaly Young Researchers and Elites Club Science and Research BranchIslamic Azad UniversityTehranIran Department of Materials and Polymer Engineering Hakim Sabzevari UniversitySabzevarIran Integrated Additive Manufacturing Center(IAM) Department of Management and Production Engineering(DIGEP)Politecnico di TorinoCorso Duca Degli Abruzzi2410129TorinoItaly

This study investigated dry sliding wear properties of AZ31 magnesium alloy and B_(4)C-reinforced AZ31 composites containing 5, 10, and 20 wt.% B_(4)C with bimodal sizes under different loadings(10-80 N) at various sliding speeds(0.1-1 m/s) via the pin-on-disc *** evaluations showed that when the distribution of B_(4)C particles was uniform the hardness of the composites increased by enhancing the reinforcement content. The unreinforced alloy and the composite samples were examined to determine the wear mechanism maps and identify the dominant wear mechanisms in each wear condition and reinforcement content. For this purpose, wear rates and friction coefficients were recorded during the wear tests and worn surfaces were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry analyses. The determined wear mechanisms were abrasion, oxidation, delamination, adhesion, and plastic deformation as a result of thermal softening and melting. The wear evaluations revealed that the composites containing 5 and 10 wt.% B_(4)C had a significantly higher wear resistance in all the conditions. However, 20 wt.% B_(4)C/AZ31 composite had a lower resistance at high sliding speeds(0.5-1 m/s) and high loadings(40-80 N) in comparison with the unreinforced alloy. The highest wear resistance was obtained at high sliding speeds and low loadings with the domination of oxidative wear.

关键词： B_(4)C AZ31 alloy Metal matrix composite Wear mechanism Bimodal

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A multi-functional dynamic state estimator for error validation:measurement and parameter errors and sudden load changes

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Frontiers of Information Technology & Electronic Engineering 2016年第11期17卷 1218-1227页

作者： Mehdi AHMADI JIRDEHI Reza HEMMATI Vahid ABBASI Hedayat saboori Department of Electrical Engineering Kermanshah University of Technology

We propose a new and efficient algorithm to detect, identify, and correct measurement errors and branch parameter errors of power systems. A dynamic state estimation algorithm is used based on the Kalman filter theory. The proposed algorithm also successfully detects and identifies sudden load changes in power systems. The method uses three normalized vectors to process errors at each sampling time: normalized measurement residual, normalized Lagrange multiplier, and normalized innovation vector. An IEEE 14-bus test system was used to verify and demonstrate the effectiveness of the proposed method. Numerical results are presented and discussed to show the accuracy of the method.

关键词： Dynamic state estimation Kalman filter Measurement errors Branch parameter errors Sudden load changes

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