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Laser Alloying of Surface of Ti-5.5Al-2Zr-1Mo-1?V Titanium near-α-Alloy Prepared Via Melted by Pulsed Laser Radiation TiC Particles
摘要： Laser alloying of the surface of Ti-5.5Al-2Zr-1Mo-1 V titanium near-α-alloy was carried out in order to improve the surface properties. The surface of the titanium alloy was being melted by pulsed laser radiation while TiC alloying powder component was being supplied to the laser irradiation zone. As a result of laser alloying, partial melting of the powder particles of titanium carbide and mixing them with the substrate metal resulted in the formation of new disperse TiC phases in the form of dendrites and highly dispersed phases. It is shown that laser alloying of Ti-5.5Al-2Zr-1Mo-1 V titanium near-α-alloy by pulsed laser radiation leads to a 1.4 times increase in hardness of the surface of the titanium alloy and reduces friction coefficient 1.2 times.
关键词： Tribological tests,Laser alloying,Microstructure,Titanium alloy
更新于2025-11-21 11:20:48
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A study of metallurgy and erosion in laser surface alloying of AlxCu0.5FeNiTi high entropy alloy
摘要： AlxCu0.5FeNiTi high entropy alloy coating is synthesized by premixed high purity Cu, Fe, Ni and Ti powders on AA1050 aluminium substrate by laser surface alloying, with the aim to improve microhardness and erosion rate. Phase constituents, microstructure and microhardness were investigated using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Vickers Microhardness tester, respectively. The erosion behavior of AlxCu0.5FeNiTi coating is checked using an air jet erosion setup. SEM images show presence of three regions. Percentage compositions of these regions are evaluated using Energy Dispersive Spectroscopy. XRD analysis of AlxCu0.5FeNiTi coating confirmed that these regions are a mixture of disordered BCC and two FCC solid solution phases. The microhardness of the AlxCu0.5FeNiTi HEA is 18 times that of the AA1050 aluminium substrate. Results show that AlxCu0.5FeNiTi HEA coating has improved erosion resistance.
关键词： Laser Surface Alloying,Microhardness,Microstructure,High Entropy Alloy,Erosion rate
更新于2025-11-21 11:18:25
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Developing New Materials for Electron Beam Melting: Experiences and Challenges
摘要： Lack of industrially available materials for additive manufacturing (AM) of metallic materials along with the promises of materials with improved or unique properties provides a strong drive for developing new process/material combinations. As powder bed technologies for metallic materials are relatively new to the market, and to some extent are only maturing, developers of new process/material combinations have certain challenges to overcome. Firstly, basic knowledge on the behavior of materials (even those well established for other applications) under extreme conditions of melting/solidification with beam-based AM methods is far from being adequate. Secondly, manufacturing of the equipment is up to date driven by industrial application, thus optimization of the AM machines for small test batches of powders is still belongs to research and development projects. Also, majority of the powder manufacturers are primarily driven by the market development, and even they are well aware of the demands imposed by the powder bed AM machines, availability of small test batches of adequate powders may be problematic or at least quite costly for the R&D oriented users. Present paper describes the experiences in developing new materials for EBM A2 machine by Arcam EBM, modified for operating with powder batches of 100-200 ml and less. In particular it discusses achievements and challenges of working with powders from different materials with specifications far beyond the range suggested by machine manufacturer. Also it discusses the possibility of using blended rather than pre-alloyed powders for achieving both composite-like and alloyed materials in the same part by steering electron beam energy deposition strategy.
关键词： Electron Beam Melting,material development,composite materials,Additive Manufacturing,blended powders,in situ alloying
更新于2025-09-23 15:23:52
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Synthesis and characterization of nickel free titanium–hydroxyapatite composite coating over Nitinol surface through in-situ laser cladding and alloying
摘要： In this study, a high power fibre laser was used to synthesize titanium hydroxyapatite composite coating over biomedical-grade Nitinol surface through laser in-situ formation, cladding and alloying processes. The laser fluence is varied in the range of 2 kJ/cm2 to 8 kJ/cm2 in view of establishing a relationship between various in-situ phase-formation characteristics along with the rate of diffusion of the base material in the cladding zone with molten pool temperature. The alloying with base Nitinol material and subsequent diffusion of titanium to the in-situ formed calcium phosphate cladding layer are observed in the samples treated with laser fluence of 4 kJ/cm2 or above. Double layer configuration of the solidified molten pool is mostly found in all the cladding samples. At the fluence of 6 kJ/cm2 or above, the top layer primarily comprises segregated titanium-hydroxyapatite phase along with diffusion of titanium from the base material. Whereas, the bottom part of the molten pool is dominated with titanium-rich nickel–titanium intermetallic reinforced with nano particles. The steady-state variations of calcium and elemental presence of titanium through the cladding cross-section along with no nickel or oxide presence are confirmed through EDS line scans. The spherical and lamellar structures of formation of titanium-hydroxyapatite on the top surface also help to improve the overall corrosion resistance properties as compared to the bare surface. The modulus of elasticity is controlled by the variation of the top layer and intermediate layer composition and thickness, which varies with laser fluence. It falls in the range of 6–30 GPa which is similar to natural bone. Thus this nickel-free alloying and cladding layer of titanium-hydroxyapatite can serve as one of the potential candidates for use as a coating over the load bearing Nitinol implants to arrest the nickel release phenomena.
关键词： Titanium–calcium coating,Biocompatible functional coating,Hydroxyapatite,Nitinol surface modification,Laser cladding and alloying
更新于2025-09-23 15:22:29
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Ultra-wide-bandgap (ScGa)2O3 alloy thin films and related sensitive and fast responding solar-blind photodetectors
摘要： Although b-Ga2O3 is considered an excellent candidate for solar-blind photodetectors (PDs) owing to its direct bandgap (4.9 eV) and high stability, the cut-off wavelength often oversteps the DUV region, reducing the rejection ratio of the PD. Moreover, oxygen vacancies, which always appear in b-Ga2O3 ?lms, act as trap centers hindering carrier recombination and signi?cantly lowering response speed. To disentangle these issues, we propose in this work to modify b-Ga2O3 by incorporating Sc to form ternary (ScGa)2O3 alloys. Thanks to the wider bandgap of Sc2O3 (~5.7 eV) than Ga2O3 and stronger SceO bonding than GaeO, the (ScGa)2O3 alloy ?lms exhibit a wider bandgap (5.17 eV) with fewer oxygen vacancies compared with pure-Ga2O3, as expected, which eventually lead to an ultra-low dark current (0.08 pA at 10 V) and faster response times (trise: 41/149 ms; tdecay: 22/153 ms) of the alloy ?lm-based PDs. Furthermore, the peak and cut-off response wavelengths of the (ScGa)2O3 PD are blue shifted relative to the pure Ga2O3 PD, resulting in a higher rejection ratio (>500 vs ~317). The Sc-alloying strategy, taking advantage of wider bandgap of Sc2O3 and stronger SceO bonding to widen the bandgap while reducing the intrinsic carriers and oxygen vacancies in the (ScGa)2O3 alloy, is expected to be generally applicable to the design of other wide-bandgap oxide alloys for developing high-performance UV photodetectors with a low dark current and high response speed.
关键词： Ga2O3 thin ?lms,Pulsed laser deposition,Solar-blind photodetectors,Sc-alloying
更新于2025-09-23 15:21:01
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Reinforcement of a laser-textured 316L steel with CuCoBe-diamond composites through laser sintering
摘要： The aim of this work was the production and the characterization of a laser textured 316L stainless steel reinforced with CuCoBe-diamond composites by laser sintering. The composites were obtained from CuCoBe and synthetic diamond with different particle sizes by mechanical alloying. The influence of the reinforcement on the physical, chemical and surface properties was analyzed. The results showed that the textured pattern consisted of square pyramids with a machined area of approximately 80%. The interfaces between the steel and the reinforcement after sintering are well defined and sharp. A good adherence of the diamond particles to the CuCoBe matrix was achieved. The laser sintering process did not induce any phase transformations or oxidation of the reinforcement. The steel reinforced with the biggest diamond particles exhibited substantially better surface performance than the untextured material.
关键词： composites,sintering,diamond,steel,Mechanical,316L,CuCoBe,alloying,texturing,laser
更新于2025-09-23 15:21:01
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Effect of indium alloying on the charge carrier dynamics of thick-shell InP/ZnSe quantum dots
摘要： Thick-shell InP/ZnSe III–V/II–VI quantum dots (QDs) were synthesized with two distinct interfaces between the InP core and ZnSe shell: alloy and core/shell. Despite sharing similar optical properties in the spectral domain, these two QD systems have differing amounts of indium incorporation in the shell as determined by high-resolution energy-dispersive x-ray spectroscopy scanning transmission electron microscopy. Ultrafast fluorescence upconversion spectroscopy was used to probe the charge carrier dynamics of these two systems and shows substantial charge carrier trapping in both systems that prevents radiative recombination and reduces the photoluminescence quantum yield. The alloy and core/shell QDs show slight differences in the extent of charge carrier localization with more extensive trapping observed in the alloy nanocrystals. Despite the ability to grow a thick shell, structural defects caused by III–V/II–VI charge carrier imbalances still need to be mitigated to further improve InP QDs.
关键词： indium alloying,InP/ZnSe,charge carrier dynamics,photoluminescence quantum yield,quantum dots
更新于2025-09-23 15:21:01
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Tin-lead Alloying for Efficient and Stable All-inorganic Perovskite Solar Cells
摘要： Cesium containing all-inorganic perovskites have received considerable interest in photovoltaics research because of their potential for improved stability compared to their organic-inorganic hybrid counterparts. However, the inorganic perovskites studied thus far still suffer from lower power conversion efficiency and long-term instability, due to an unfavorable bandgap and either phase instability or air-sensitivity. Herein, A strategy to mitigate these concerns is investigated by alloying tin and lead on the B site to form tin-lead alloyed low-bandgap (~1.34 eV) inorganic CsSn0.3Pb0.7I3 perovskites. Solar cells made using this material in an inverted full-structured architecture with a PEDOT:PSS hole transport materials (HTM) attain power conversion efficiency (PCE) up to 9.41% (stabilized PCE 7.23%). Furthermore, a simple HTM-free device without PEDOT:PSS layer is demonstrated more stable than the full-structured device and exhibits a PCE of 7.60% (stabilized PCE 7.31%) – the highest efficiency to date for an inorganic perovskite with a bandgap below 1.40 eV. This simplified device structure shows good reproducibility and stability. This work provides a possible route for fabricating low-cost, high stability devices with competitive efficiencies.
关键词： tin-lead alloying,solar cells,all-inorganic perovskite,low-bandgap,stability
更新于2025-09-23 15:19:57
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1D/3D Alloying Induced Phase Transition in Light Absorbers for Highly Efficient Sb <sub/>2</sub> Se <sub/>3</sub> Solar Cells
摘要： Simple binary inorganic antimony selenide (Sb2Se3) compound is attractive as a promising light absorber for low-cost and high-efficiency photovoltaic. The external quantum efficiencies of Sb2Se3 solar cells are now approaching the optical limit values, which are comparable with the traditional well-developed solar cells (such as Si, CuInGaSe2, CdTe, etc). However, the power conversion efficiency of the Sb2Se3 devices is constrained by the open-circuit voltage (VOC) deficit, due to the intrinsic high resistivity and low element-doping efficiency in such one-dimensional (1D) crystals. In this work, a highly conductive, 3D crystal-structure AgSbSe2 phase, formed by phase transition from low symmetry binary Sb2Se3, is introduced to control the doping density in the alloyed (Sb2Se3)x(AgSbSe2)1-x films by utilizing configurational entropy. Guided by this alloying concept, 1D-3D (Sb2Se3)x(AgSbSe2)1-x alloy films with tunable doping densities are obtained. As a consequence, a noticeable improvement in VOC by >18% is observed in solar cells based on (Sb2Se3)x(AgSbSe2)1-x alloy absorber layer, as compared to the reference cell with a pure Sb2Se3 absorber, leading to a high conversion efficiency of 7.8%. This alloying model provides a universal approach to control the photoelectrical properties for high-efficiency Sb2Se3-based solar cells.
关键词： thin film solar cells,light absorber,voltage deficit,antimony selenide,1D/3D alloying
更新于2025-09-23 15:19:57
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Tuning the Emission Colors of Self-Assembled Quantum Dot Monolayers via One-Step Heat Treatment for Display Applications
摘要： Homogeneously self-assembled colloidal semiconductor quantum dot monolayers (QD-SAMs) over large areas are promising materials for thin film optoelectronic device applications, especially for display. Although tuning of emission colors from QDs is generally achieved during wet chemical synthesis and before monolayer formation, we propose in this study a simple and effective method to adjust emission colors after the formation of QD-SAMs by a simple one-step heat treatment. CdSe-based core/shell or core/double shell structured QDs (CdSe/ZnS, CdSe/CdZnS, and CdSe/CdS/ZnS) covered with an optimal set of hydrophobic ligands can form homogeneous and stable QD-SAMs at the air-water interface. The QD-SAMs are subsequently transferred onto hydrophobized glass substrates by the Langmuir-Schaefer (LS) method and thermally treated in air. We found a blueshift of more than 35 nm for the emission wavelength (red to green) by a thermal treatment at 280 °C for 150 min with CdSe/ZnS QD-SAMs. The color can be adjusted by changing the heating temperature and the treatment time. The wavelength shift is in the order of CdSe/ZnS(4L) > CdSe/ZnS(6L) = (CdSe/CdZnS) > (CdSe/CdS/ZnS). The energy dispersive X-ray (EDX) microanalysis of a single QD reveals that the blueshift is mainly caused by atomic diffusion-induced alloying of core/shell type QDs. The main problem of this method is the decreasing emission intensity caused by oxidation during the heat treatment; however, this problem can be solved by use of a SiO2 protective coating on the QD-SAMs. We believe that this simple technique is useful for manufacturing RGB-colored ultrathin QD-SAM films for QDs displays such as QD film display, QD color-filter display, and QD light emitting diode.
关键词： QD Display,Quantum dots,Color tuning,Self-assembled monolayer,atomic diffusion-induced alloying,Thermal treatment
更新于2025-09-23 15:19:57