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ZrN and TiNiN nanolayers are alternately deposited on silicon substrate by magnetron sputtering. A series of ZrN/TiNiN nano-multilayer films with different Ni contents are prepared by varying the Ni:Ti volume ratio of the targets. The effects of Ni content on the microstructures and mechanical properties of ZrN/TiNiN nano-multilayer films are studied by X-ray diffractometer (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and nanoindentation instrument. The results show that with the increase of Ni content, the crystallization degree of ZrN phase first increases and then decreases. Besides, the hardness, elastic modulus and toughness of the films also increase first and then decrease with Ni content increasing. When Ni:Ti= 1:24, the ZrN/TiNiN nano-multilayer films obtain the highest hardness, elastic modulus and fracture toughness, which are 23.2 GPa, 317.8 GPa and 2.29 MPa·m1/2, respectively. This is mainly attributed to the best columnar crystal growth of the ZrN/TiNiN nano-multilayer film. The TiNiN layer changes into face centered cubic structure under the template of ZrN layer, and grows in coherent epitaxy with ZrN layer. ● A series of ZrN/TiNiN nano-multilayer films with different Ni contents are prepared by magnetron sputtering. ● When Ni:Ti= 1:24, the ZrN/TiNiN nano-multilayer films simultaneously obtain the highest hardness and fracture toughness. ● The high hardness and toughness are due to that the TiNiN layer grows in coherent epitaxy under the ZrN layer template. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM), as a powder-bed-based additive manufacturing technology, is a promising technology for manufacturing metal parts with high geometric complexity. The prediction of the SLMed microstructure, a key approach to manipulate the microstructures and performances, is challenging due to the complex heat history involving multiple thermal cycles. In the work, the microstructural simulation of solidification and solid-state phase transformation processes under various spatially variable thermal cycles of SLM was investigated by a developed two-dimensional cellular automaton (CA) model considering the temperature distribution and transient thermal history. The morphology and size of the β grain and martensite simulated by the model agree well with the experimental results in single-layer, thin-wall and multi-track multi-layer samples. Based on the simulated results, there are three zones (powder melting, remelting and reheating zones) and four stages (powder melting, mushy, multi-phases and solid-state phase transformation stages) during SLM depositing Ti 6Al 4V alloy. The morphology, growth direction and size of prior β grains depend mainly on the direction of heat flux and overlapping of adjacent deposited tracks. Six evolutional types of β grains exist including disappearance, morphological change, size increasing to be a stable value, growing, size decreases to be a stable value, and no evolution. The prediction of microstructure in SLMed alloy can be realized by the developed CA model. [ABSTRACT FROM AUTHOR]

Highlights: [•] The 320°C isothermal section of the Mg–Nd–Zn system was well established. [•] Eight ternary phases (τ1–τ7 and T-NdMg12) were found at 320°C. [•] T-NdMg12 is the Nd-stabilized NdMg12 phase. [•] T-NdMg12 and τ5–τ7 can be regarded as the newly found ternary phases. [ABSTRACT FROM AUTHOR]

• Mn-Cu alloys are fabricated by laser powder bed fusion based on mixed element powders. • The optimal processing windows for the dense Mn-Cu alloys is discovered. • The as-fabricated Mn-Cu alloys present good tensile properties. Mn-Cu alloys with high Mn contents have good damping capacity but poor workability and mechanical properties. In this research, laser powder bed fusion (LPBF) was applied to fabricate the Mn-Cu alloys (Mn 63 Cu 37 , Mn 73 Cu 27 , and Mn 82 Cu 18) based on mixed element powders. The printability, microstructure and mechanical properties of the as-fabricated Mn-Cu alloys were investigated through a series of characterization methods. The results indicate that the Mn-Cu alloys with high relative densities (99.76–99.85%) can be fabricated using the optimal processing parameters. The as-fabricated Mn-Cu alloys show higher strengths (537.5–589.6 MPa) and yield strengths (404.0–440.1 MPa) than those of commercial Mn-Cu alloys fabricated by conventional methods. The tensile strength presents an overall downward trend with increasing Mn content. Thus, LPBF can be considered as a promising method to fabricate Mn-Cu alloys with high Mn contents. [ABSTRACT FROM AUTHOR]

Abstract: ZnO films with three different microstructures including hexagonal prisms, plates and rose-like twinned crystals were fabricated using chemical bath deposition with different concentration of gelatin. The growth mechanisms of ZnO films were discussed, and the gelatin played a vital role as a polyelectrolyte capping the formation of microstructures. The photoluminescence and Raman properties were found sensitive to the crystal morphologies of ZnO films. Significantly, the photodegradation efficiencies of methylene blue under UV light irradiation in the presence of ZnO films consisted of hexagonal prisms and rose-like twinned crystals were 95% and 96%, respectively. The excellent photocatalytic activities can be ascribed to the high oxygen vacancies concentration and high percentage of polar planes, and this result was important in addressing the origin of high photocatalytic activity. [Copyright &y& Elsevier]

• The phase equilibria of the Cr-Mn-Co ternary system were investigated. • Isothermal sections at 900, 1050, 1150, and 1200 °C were determined. • The σ phase forms a continuous solid solution from Cr-Co side to Cr-Mn side at all temperatures investigated. • The solubility of Co in the (Cr) phase decreases with the increasing Mn content at all temperatures investigated. [Display omitted] The equilibrated microstructures in the Cr-Mn-Co ternary alloys annealed at 900, 1050, 1150, and 1200 °C were studied using X-ray diffraction (XRD) and electron probe micro analyzer (EPMA). The results are summarized as follows: (1) the σ phase has a wide solubility range from Cr-Co side to Cr-Mn side at all temperatures investigated; (2) the σ phase region becomes narrower as the temperature increases from 900 to 1200 ℃; (3) The (αCo) phase has a significant solubility for Cr which decreases with increasing Mn content; (4) the solubility of Co in the (Cr) phase decreases with the increasing Mn content at all temperatures investigated; (5) the solubility of Cr in the (βMn) phase slightly increases as the temperature increases from 900 to 1150 ℃, while the solubility of Co changes hardly. The experimental information obtained from this study is not only useful for the thermodynamic assessment of the Cr-Mn-Co ternary system, but also significant for the alloy design of high entropy alloy. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) technology is currently undergoing rapid development in the aerospace field. However, due to the intense cracking susceptibility, additive manufacturing of nickel-based single-crystal (SX) superalloys still presents major challenges. In this paper, the crack-free SX superalloy is fabricated directly using pulsed laser. The microstructure and stress rupture property of the additively manufactured SX superalloy after heat treatment are carefully investigated and compared with conventional cast alloy. The results show that the stress rupture life of the AM sample (66.4 h) is longer than that of the cast sample (59.1 h). This is related to the difference of microstructure between AM and cast samples. AM samples have a finer dendritic structure and lower inter-dendritic segregation, which is conducive to solution strengthening and avoids the formation of TCP phase. Besides, the carbides in the AM sample is finer and evenly distributed, which is conducive to precipitation strengthening; The fine carbides are enveloped within layers of γ′ in the AM samples, which avoids the formation of cracks caused by separation of carbides and the matrix. All of those are beneficial to improve stress rupture properties. • AM sample had fine dendrites, small carbides and homogeneous element distribution. • Dot-like MC Carbides of AM sample was enveloped by γ′ film after heat treatment. • Carbides in the AM sample hardly broke or separated from the γ matrix. [ABSTRACT FROM AUTHOR]

The microstructure and properties of Cu-0.42Cr (wt.%) and Cu-0.45Cr-0.14Ti (wt.%) alloy subjected to cold rolling and aging treatment are investigated through tensile testing, electrical conductivity measurement, scanning electron microscopy, and transmission electron microscopy. Results show that the tensile strength of Cu-0.45Cr-0.14Ti (wt.%) alloy enhances as the degree of deformation increases, but the degree of deformation slightly influences electrical conductivity. When deformation is changed, electrical conductivity is basically unchanged. The good combination of strength and electrical conductivity, which reach 610 MPa and 55.4% IACS, respectively, can be obtained in the Cu-0.45Cr-0.14Ti (wt.%) alloy after 80% cold rolling and aging at 450 °C for 15 min. Ti inhibits the growth of the Cr precipitation phase and enhances the precipitation strengthening effect. Ti mainly exists in the matrix in the form of solute atoms, which do not form a separate lattice structure after aging treatment. • The alloy material is prepared by a process method combining solid solution aging treatment and deformation treatment. • Ti element enhances the effect of age hardening and significantly improves the mechanical properties of the alloy. • Titanium atoms segregate around the Cr phase to slow down the rate of precipitation coarsening. • Ti atoms have never formed a separate lattice structure in the Cu-0.45Cr-0.14Ti (wt.%) alloy. [ABSTRACT FROM AUTHOR]

Nickel-based Single Crystal (SX) superalloys have an excellent creep ductility and thermal fatigue resistance at elevated temperatures. But SX structure is difficult to be manufactured under the demand of increasing operating temperature and complex shapes. In this work, the feasibility of manufacturing Nickel-based SX-superalloys by selective laser melting (SLM) was investigated theoretically and experimentally. Firstly, the solidification conditions including temperature field, thermal gradient and solidification speed of the SLMed multi-track samples were calculated by an established finite element model to judge the theoretical feasibility based on the columnar to equiaxed transition (CET). Then, the single-track, triple-track and cuboid samples on a single-crystal SRR99 substrate were deposited to judge the experimental feasibility and explore their grain growth mechanism during SLM. The results showed that CET can be avoided during the whole process of SLM. The unidirectional SRR99 SX structure with a height of 2 mm can be successfully obtained by SLM. On horizontal section, the microstructures can be divided into [001] orientation zone, [010] orientation zone and overlapping zone with a typical secondary dendrite structure. On vertical section, the columnar dendritic structure along the dominant thermal gradient direction is present. The primary dendrite spacing of the SLMed samples (∼1–2 μm) is more than two orders of magnitude lower than that of the cast one (∼320 μm). So, SLM technology possesses the capacity to manufacture SX superalloy. When the deposited height reaches 6 mm, the misorientation angle is about 25° and a crack initiates. Finally, the grain growth mechanism of the SLMed SRR99 single-crystal superalloy was proposed based on the local thermal gradient, the existing well-aligned crystallographic orientation and the preferential grain growth direction. • Solidification conditions of the SLMed samples were calculated by a finite element model. • Columnar to equiaxed transition can be avoided during the whole process of SLM. • The single-crystal alloy with a height of 2 mm can be obtained by SLM. • The grain growth mechanism of the single-crystal superalloy was proposed. [ABSTRACT FROM AUTHOR]

Abstract: The dynamic oxygen storage capacity (DOSC) and rate (DOSR) over Mn0.1Ce0.9O x and Mn0.1Ce0.6Zr0.3O x prepared by sol–gel method were investigated. The results show that Ce-based compounds containing Mn oxides with variable valences contribute to the majority of DOSC and DOSR performances at low temperature, and the DOSC and DOSR of Mn–Ce–O can be enhanced by the Zr addition at high temperature. Both materials were characterized by XRD, BET, Raman, TPR, EPR and XPS. XRD and Raman results indicate that Mn0.1Ce0.9O x and Mn0.1Ce0.6Zr0.3O x are characterized with the fluorite-type cubic structure similar to CeO2, and furthermore the thermal stability of M–Ce–O materials is improved by the introduction of some Zr atoms. EPR researches reveal that there are three types of Mn2+ species: isolated Mn2+ substituting for Ce4+ ions in the lattice with a cubic symmetry, ones in defect with a noncubic symmetry and at the surface of samples. From XPS, it can be concluded that Mn2+/Mn3+ redox couples exist on the surface of Mn0.1Ce0.9O x and Mn0.1Ce0.6Zr0.3O x samples. [Copyright &y& Elsevier]

The 2195 Al-Cu-Li alloy is widely utilized in the aerospace industry due to its lightweight nature and high strength. Consequently, gaining a comprehensive understanding of techniques to enhance its microstructural and mechanical properties is crucial for the consistent production of reliable and high-strength aerospace components. In this investigation, a pristine 2195 industrial ingot was subject to three distinct forging pretreatments: PT1, which involved a direct three upsetting and three stretching (3U3S) process; PT2, which combined double stage homogenization (DH) with 3U3S; and PT3, which involved DH along with six upsetting and six stretching (6U6S). Subsequent warm deformation and T8 aging treatment were applied to the pretreated forgings. The microstructure evolution during the processes and the final mechanical properties in three orthogonal dimensions were examined. The findings revealed that the combination of DH and multi-dimensional forging (MDF) facilitated the dissolution of non-equilibrium phases to a greater extent. Consequently, the main strengthening phase transformed from the T 1 + δ' phase observed in PT1 to the denser T1 + little θ' phase observed in PT2 and PT3 after T8 aging treatment. Notably, the tensile strength and yield strength of PT2 and PT3 specimens increased by 20–30 MPa in all three directions. Moreover, the MDF process accelerated the recrystallization behavior from PT1 to PT3, resulting in a gradual reduction in the average grain size of the pretreated samples from 356 µm to 186 µm. Following warm forging and T8 aging, the grains exhibited a finer and equiaxed structure. Additionally, the coarse phase was identified as the primary source of transgranular cracking. The coarse phases within the matrix became more homogeneous and finer from PT1 to PT3, with a gradual decrease in their area fraction. On the fracture surfaces, the aggregation of coarse phases diminished. Consequently, the elongation in the z-direction improved, and the elongation anisotropy and standard deviation decreased in all three directions for PT3 specimens. The findings presented in this study provide valuable insights into the high-performance manufacturing of Al-Cu-Li alloys. • The DH and doubling the strain of MDF both promoted the dissolution of non-equilibrium phases. • Combine DH treatment with MDF enhanced the precipitation kinetics of the T 1 phase, increasing the strength by 20–30 MPa. • The coarse phase was the main transgranular cracking sources, which was diminished gradually by the improved process. [ABSTRACT FROM AUTHOR]

Four groups of newly developed Ni-based superalloy samples with different Zr contents were manufactured by Direct energy deposition (DED). This study focuses on the influence of Zr element concentration on microstructure and cracking formation mechanism in DED-processed Ni-based superalloy ZGH451. Although Zr content is low, it strongly affects the formation of the precipitated phase and hot tearing tendency. Measurement of the crack area showed that the crack density value increases with the Zr concentration. According to thermodynamic simulation results and microstructures observed, Zr microsegregation in the interdendritic regions and considerable amounts of Zr is present in oxides or carbides. Zr contributes to forming large-size carbides mainly due to zirconia providing nucleation sites and the dissolution of Zr. Simultaneously, the solidification has been retarded due to the continuous accumulation of large Zr atoms, which increases the γ-γ′ eutectic fraction. Moreover, Zr addition could effectively decrease the solidus temperature of ZGH451 alloys, leading to the critical liquid film at the end of solidification. Based on these results, staying below 0.05 wt% of Zr content to reduce the risk of hot tearing in additive manufacturing superalloy was proposed. • A newly designed ZGH451 superalloy with different Zr contents is successfully produced by direct energy deposition. • The effect of Zr contents on various precipitation phases and microstructure of ZGH451 superalloy is revealed. • The hot cracking formation mechanism in Zr-modified ZGH451 superalloy is systematically studied. • An upper limit for the Zr content of 0.05 wt% is proposed to optimize alloy design for AM superalloy. [ABSTRACT FROM AUTHOR]

Abstract In the present study, the Ti-Ni-Zr alloy ribbons with the various Zr contents were fabricated at the optimum process conditions. The crystallization process and the effect of the following annealing treatments on the microstructural evolution, martensitic transformation behavior, mechanical properties and shape memory effect of the annealed Ti-Ni-Zr alloy ribbons were investigated systematically. The results revealed that the phase constituents were dependent on the Zr contents, and can be tailored by the annealing treatment. The λ1 precipitate existed in all annealed Ti-Ni-Zr alloy ribbons and NiZr phase appeared only in the annealed Ti-Ni-Zr alloy ribbons with the Zr content more than 25 at.%. With the annealing temperatures increasing, the martensitic transformation temperature increase. And the Ti-Ni-Zr alloy ribbons with the higher Zr content showed the relatively lower transformation temperatures owing to the presence of the NiZr precipitate. The nano-scale λ1 precipitate and NiZr phase can enhance the matrix strength and improve the mechanical properties, while the appearance of the lots of the NiZr phase would deteriorate the shape memory effect. Among, the annealed Ti-Ni-Zr alloy ribbon showed the excellent combination of the higher transformation temperatures, superior mechanical and strain recovery characteristics. In summary, the evolution of the microstructure containing the martensitic/austenitic state, type/size of the precipitate, and distribution state of the precipitate resulted in the changing of the martensitic transformation, mechanical properties and shape memory effect. Highlights • The higher quality Ti-Ni-Zr alloy ribbons with various Zr contents were prepared. • The phase constituents of Ti-Ni-Zr alloy ribbons depended on annealing parameters and Zr contents. • One step B2↔B19′ martensitic transformation occurred in the annealed Ti-Ni-Zr alloy ribbons. • The mechanical and functional properties were affected by Zr contents and annealing parameters. [ABSTRACT FROM AUTHOR]

Abstract An equiatomic AlCrCuFeNi high entropy alloy (HEA) is fabricated successfully from the alloy powders using selective laser melting (SLM). Microstructural characteristics and mechanical behavior of SLMed AlCrCuFeNi samples under optimal SLM processing parameters are studied in detail. It is revealed that the SLMed AlCrCuFeNi HEA shows high crack sensitivity, and the optimum processing window is narrow. The formation of FCC phase is inhibited, resulting in a simple BCC solid solution to accommodate high lattice distortion and elastic strain induced by rapid cooling rate for the SLMed AlCrCuFeNi HEA. Moreover, unique fine columnar grains containing multiple ultrafine sub-grains structures appear within the molten pool and present a <100> preferred orientation. Nano-scale Cu-rich phases precipitate and exhibit chain-like at HAGBs while granular shape at LAGBs. Also, anomalous alternating bright and dark structures containing B2 and A2 phases with the width about 22 nm appear at the sub-grain boundaries due to rapid solidification. The SLMed AlCrCuFeNi HEA possesses superior properties with a compression strength of 2052.8 MPa and a fracture strain of 6.8% compared to the corresponding casting material. Fracture analysis indicates that the SLM (0°) specimen exhibits quasi-cleavage fracture while the SLM (90°) specimen shows intergranular fracture. The grain boundary strengthening effect, <100> preferential growth orientation of BCC grain and the existing microcracks are proposed to explain the anisotropy of compression properties. Highlights • A dual-phase high entropy alloy is fabricated using selective laser melting. • Unique columnar grains containing multiple ultrafine sub-grains are discovered. • Nano-scale Cu-rich phases exhibit chain-like at HAGBs while granular at LAGBs. • Anomalous spinodal structures containing B2 and A2 phases are discovered. • Anisotropy of compression properties exists in the SLMed AlCrCuFeNi alloy. [ABSTRACT FROM AUTHOR]

The rapid solidified Ti-Ni-Zr amorphous ribbon was crystallized to B2 phase and λ1 phase. The phase constitutions of Ti-Ni-Zr alloy ribbon were dependent on the annealing temperatures. The annealed ribbon with the annealing temperature of 773 K and 873 K consisted of B2 parent phase and λ 1 phase. When the annealing temperature increased to 973 K, the B19′ martensite can be introduced except from the B2 phase and λ 1 phase. With further increasing the annealing temperature to 1073 K, only B19′ martensite and λ 1 phase was observed. The transformation temperatures increased successively with the increasing of the annealing temperature, which was closely related to the variation of the phase constituents. The annealed ribbons with the moderate annealing treatment showed the higher transformation temperature and the superior thermal cycling stability. [ABSTRACT FROM AUTHOR]

In this work, the WC-Cr 2 (C, N)-Co nanocomposites were synthesized by using the one-pot carbothermal reduction nitridation hydrothermal precursor method. The preparation mechanisms, including phase and morphology evolutions, were investigated by differential thermal analysis (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and thermodynamic analysis. The results showed that phase evolution, with temperature increasing, follows the sequences of (amorphous phase, WO 2.72) → (CoWO 4 , WO 2.72 , WO 2 , CrWO 3) → (WO 2 , CoWO 4 , Co 6 W 6 C, CrWO 3) → (W 2 C, Co 3 W 3 C, WC) → (WC, W 2 C, Co 3 W 3 C) → (WC, Co, Co 3 W 3 C trace amount). Through comparing different heat treatment conditions, the powder particle size was more easily affected by temperature than holding time. The higher temperatures or longer time holding resulted in the aggregation of powder particles. Finally, WC-Cr 2 (C, N)-Co nanopowders with about 60 nm were obtained at 1050 °C for 1 h under the N 2 flow of 1 L/min with the oxygen content of 0.22 wt% and the free carbon content of 0.19 wt%. The TEM elements mapping revealed that Cr distributes uniformly with WC grains, Co and WC grains are combined well. The surface of WC-Cr 2 (C, N)-Co determined by XPS is mainly composed of W, Co, Cr, C, N, and O. The spark plasma sintering (SPS) sintered WC-Cr 2 (C, N)-Co composite shows a nanocrystalline microstructure with the average grain size ∼170 nm, and the excellent comprehensive mechanical properties with the Vickers hardness 1730 Kg·mm−2 and fracture toughness 11.5 MPa·m1/2, respectively. • The novel WC-Cr 2 (C, N)-Co nanocomposites were synthesized by using the one-pot carbothermal reduction nitridation hydrothermal precursor method. • The preparation mechanisms including phase and morphology evolutions, microstructure, chemical composition, and distribution were systematically investigated. • WC-Cr 2 (C, N)-Co nanopowders with about 60 nm were obtained at 1050 °C for 1 h under the N 2 flow of 1 L/min with oxygen content of 0.22 wt% and free carbon content of 0.19 wt%. • Through TEM and SEM characterization, the composition elements of the composite powder were evenly distributed, Co and WC grains are combined well. • Nano-WC-Cr 2 (C, N)-Co cemented carbides (∼ 170 nm) showed excellent comprehensive mechanical properties with Vickers hardness and fracture toughness of 1730 Kg mm−2 and 11.5 MPa m1/2, respectively. [ABSTRACT FROM AUTHOR]

The 2195 Al-Cu-Li alloy is widely utilized for the fabrication of key aerospace vehicle components; hence, an in-depth understanding of its hot deformation behavior is essential for consistently achieving high-performance products. In this study, isothermal compression tests were performed on 2195 Al-Cu-Li alloy ingots in the temperature and strain rate ranges of 250–500 °C and 10−3-1 s−1, respectively. A processing map was established to predict the workability under different conditions. The corresponding microstructures were examined to reveal their hot deformation mechanism. Results demonstrated that the processing map was divided into four distinct domains. The unstable zone was located in the 250–375 °C/10−1.5-1 s−1 and 250–275 °C/10−2.5–10−1.5 s−1, temperature/strain rate regimes, in which deformation bands and flow localization were observed. The deformation bands blocked dislocations and compromised the dynamic recrystallization (DRX) behavior, hence damaging the microstructure. Further, large coarse T 1 phases precipitated in the 325–410 °C/10−2.5–10−3 s−1 regime, which led to the formation of heterogeneities in the microstructure, corresponding to a minimum workability in the processing map. The optimal hot-working domain for the 2195 alloy was determined to be 460–500 °C/10−3–10−2 s−1, and the dominating hot deformation mechanisms were DRX and dynamic recovery (DRV). Specifically, continuous and discontinuous DRX behaviors dominated in the 300–400 °C/10−3 s−1 and 450–500 °C/10−3 s−1 regimes, respectively. DRX gradually weakened as the strain rate increased at 500 °C. Further, the weakening of DRX was only minimally affected by temperature at 400–500 °C during high-speed deformation (1 s−1). The results reported herein can provide valuable insights into the hot working of Al-Cu–Li alloys. • A processing map (PM) was established to accurately predict the hot deformation behavior of the 2195 alloy. • Deformation bands and flow localization were the main microstructure response in the unstable domain. • Large coarse T 1 phases precipitated in the precipitation sensitive domain, leading to heterogeneity deformation. • The optimal hot working domain was 460–500 °C/10−3–10−2 s−1, which was dominated by DRX and DRV. • Within the 300–400 °C/10−3 s−1 regime, CDRX was the main DRX mechanism, whereas DDRX predominant at 450–500 °C/10−3 s−1. [ABSTRACT FROM AUTHOR]

As an additive manufacturing technology, Fused Deposition Modeling and Sintering (FDMS) technology can give diamond tools some creative structures to be applied in more fields. To explore the influence of diamond parameters on diamond tools manufactured by FDMS, copper-tin-diamond composite samples with different diamond concentrations and particle size were prepared by FDMS technology in this paper. During the study, the morphological characteristics of diamond particles inside the samples during the debinding and sintering process are summarized and the influence of diamond parameters on the mechanical properties and structure of the samples was further explored. These influence laws were also verified by cutting experiments. The results show that most diamond particles are in an incomplete coating state because of the volatilization of the binder. Meanwhile, a higher concentration of diamond will lead to more pores and cavities in the samples; and the cavities can be connected to form a large area of cavity zone by the print layer, thereby resulting in a serious loss in the performance of the samples. On the other hand, a small diamond particle size can lead to agglomeration of particles. Subsequently, this will result in void generation and regional weakening of the holding ability. However, agglomeration and some pores or cavities will increase the wear of the matrix, expose more diamond particles, and finally improve the cutting efficiency of the dicing blades when cutting sapphire crystal. Excessive wear may reduce the life of the diamond tool, but improved of sharpness can be better applied in the field of precision machining. • Higher concentration of diamond will lead to more pores and cavities. • The cavities will be connected and form a cavity zone due to FDMS process. • Agglomerates can lead to void generation and weakening of the holding ability. • Increased diamond concentration amplifies the effect of particle size on agglomeration. • Appropriate diamond parameters can prevent crack propagation. • Characteristic endowed by FDMS will improve the cutting efficiency of tools. [ABSTRACT FROM AUTHOR]

Abstract: A ternary alloy with composition of Mg–11Gd–1Zn (mass fraction, %) was prepared by conventional casting and extrusion. The microstructure and aging behavior of the alloy prepared was investigated. The results showed that the as cast microstructure of the alloy consisted of the α-Mg matrix, (Mg,Zn)3Gd eutectic and a 14H long-period staking ordered (14H-LPSO) phase. After extrusion the (Mg,Zn)3Gd eutectic networks were destroyed and its broken particles were arranged in strips along the direction of extrusion, and the 14H-LPSO phase distributed between (Mg,Zn)3Gd strips. Solid solution treatment at high temperature above 500°C caused the dissolution of (Mg,Zn)3Gd phase into the matrix and increase of the 14H-LPSO phase. Precipitation of β′ and β1 metastable phase occurred when the solution treated specimens were aged at temperature of 225°C (T6 treatment) and the 14H-LPSO phase formed during prior solution treatment remained in the microstructure after aging. Aging conducted on the extruded alloy (T5 treatment) also caused the formation of both of β′ and β1 precipitates, however the volume fraction of 14H-LPSO phase in the T5 treated specimens was lower than that in specimens after T6 treatment. High tensile strength combined with good ductility was obtained from the alloy after T6-aging. [Copyright &y& Elsevier]

• Co-based diamond composites were separately fabricated via the FDMS and the powder hot-pressed sintering technology. • There is a certain difference in the overall performance of the two kinds of specimens. • The Co-based samples fabricated by FDMS form a special coating state for diamond particles. • The Co-based samples fabricated by FDMS have defects of high porosity inside the matrix. • The reduction of knife-cut features can represent the improvement of density and holding ability of the FDMS sample. Fused deposition molding and sintering (FDMS) technology has the characteristics of low cost and low damage to diamonds. In order to explore more possibilities of additive manufacturing diamond tools, FDMS technology was considered to manufacture Co-based diamond composites at different temperatures in this paper. Also, specimens of Co-based diamond composites were manufactured under the same sintering process by using the powder hot-pressed sintering technology. And the matrix microstructure and properties of the specimens made by those two different technologies were analyzed and compared. The results show that a lot of porosity defects were developed inside the specimens manufactured by FDMS. This is because of the specific process characteristics of FDMS. Also, the matrix forms a special coating state for diamond particles due to the binder system used in this study, which causes some diamond particles to suffer slight thermal damage. These all will reduce the density and holding ability of the FDMS specimens. However, when the sintering temperature increases from 800 °C to 880 °C, the performance loss of FDMS samples caused by the porosity defects gradually decreases, thereby reducing the performance difference when comparing with the powder hot-pressed sintering specimens. In addition, the matrix structural uniformity of the FDMS specimens is significantly improved during this process, and the fracture feature changes from intergranular fracture to transgranular fracture. But there is still a certain difference in the overall performance of the two kinds of specimens at the optimal sintering temperature. Therefore, the further optimization of FDMS process parameters and binder system is of great significance for the application of FDMS in diamond tools. [ABSTRACT FROM AUTHOR]