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Journal of Alloys and Compounds
Elsevier Science S.A.
Journal of Alloys and Compounds

Elsevier Science S.A.

0925-8388

Journal of Alloys and Compounds/Journal Journal of Alloys and CompoundsSCIISTPEI
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    The influence of advanced hot isostatic pressing on phase transformations, mechanical properties of Ti-34Nb-13Ta-5Zr-0.2O alloy manufactured by In-situ alloying via selective laser melting

    Kong W.Wang F.Attallah M.M.Francis E.M....
    9页
    查看更多>>摘要:? 2022 Elsevier B.V.In this paper, advanced hot isostatic pressing (HIP) subjected to high and intermediate cooling rate (HCR & ICR) were exploited to close keyholes and tune the microstructure of SLMed Ti-34 Nb-13Ta-5Zr-0.2 O alloys (TNT5Zr-0.2 O, wt%). XRD analysis along with SEM and TEM micrographs reveal single beta phase in grain matrix of as-fabricated TNT5Zr-0.2 O (TNT5Zr-0.2 O-AF), TNT5Zr-0.2 O-HCR, TNT5Zr-0.2 O-ICR alloys. Additionally, high-angle annular dark-field (HAADF) micrographs show discrete large Ti-rich α grain boundary precipitates in TNT5Zr-0.2 O-ICR alloy. Tensile properties show that TNT5Zr-0.2 O-AF alloy possessed high UTS of 975 ± 12 MPa, and elongation of 4.9% ± 0.3%; the TNT5Zr-0.2 O-ICR alloy obtained slightly higher UTS (1036 ± 26 MPa) and lower elongation (3.0% ± 0.3%). S-N curves demonstrate fatigue limit of TNT5Zr-0.2 O-ICR alloy (150 MPa) is slightly higher than the counterpart of TNT5Zr-0.2 O-AF alloy (130 MPa), and slip-band cracking phenomenon was observed in both alloys. Advanced HIP subjected to intermediate cooling rate functions well to close SLM-processed keyholes but the resistance to fatigue is not markedly enhanced; the addition of proper amount oxygen interstitial solutes in TNTZ-O alloy is regarded as an inexpensive, effective strengthening technique for load-bearing biomedical applications.

    Coercivity and remanence enhancement in hot-deformed Nd-Fe-B magnets by high-temperature short-term annealing process

    Zhang T.Wu Z.Yu R.Zhang L....
    10页
    查看更多>>摘要:? 2022 Elsevier B.V.It is challenging to simultaneously improve the coercivity, remanence and squareness factors of sintered and hot-deformed magnets, because of the complicated influences by various microstructure factors. In this work, we demonstrate that the coercivity, remanence and squareness factor of hot-deformed Nd-Fe-B magnet can be enhanced simultaneously by high-temperature short-term annealing process. The coercivity of the hot-deformed sample increased from 1.05 T to a maximum of 1.28 T after annealing at 800 °C, and decreased to 0.87 T at 900 °C. The remanence of the hot-deformed sample increased continuously from 1.41 to 1.49 T as the annealing temperature increased to 900 °C. The calculated squareness value firstly increased from 0.91 to 0.97 at 850 °C, then decreased to 0.74 at 900 °C. An block-shaped Nd-Fe-rich phase, Nd6(Fe,Co)13Ga, was identified in hot-deformed sample. The improvement of coercivity is due to the melting and infiltration of Nd6(Fe,Co)13Ga phase from the surface of powder flakes into the grain boundaries during annealing process. The slightly anisotropic growth of Nd2Fe14B grains results in an improved grain alignment thus the enhanced remanence. Furthermore, the melting point of Nd6Fe13Ga (810 ℃) and Nd6(Fe,Co)13Ga (760 ℃) phases were confirmed by DSC, indicates that adding a small amount of Co element in Nd6Fe13Ga compound can significantly reduce its melting point. Due to the micrometer scale infiltration distance from powder flake surface into the grain boundaries, a balance between infiltration within the powder flakes and grain growth can be achieved under the present processing conditions. This opens up a new route to improve the coercivity, remanence and squareness factor simultaneously for hot-deformed Nd-Fe-B sample.

    Investigation of substitution effects of the first four lanthanides (La, Ce, Pr and Nd) in yttrium iron garnet

    Norkus M.Vistorskaja D.Skaudzius R.Beganskiene A....
    12页
    查看更多>>摘要:? 2022 Elsevier B.V.In this study, the substitution effects of the first four lanthanides (La, Ce, Pr and Nd) in yttrium iron garnet (Y3Fe5O12, YIG) have been investigated for the first time to the best our knowledge. The Ln-substituted yttrium iron garnets (Y3?xLnxFe5O12, where Ln = La, Ce, Pr and Nd; x = 0.0; 0.75, 1.5, 2.25, 3.0) were prepared by an aqueous sol–gel method. The phase purity and structure of synthesized Y3?xLnxFe5O12 specimens were estimated using XRD analysis, FTIR spectroscopy and M?ssbauer spectroscopy. It was demonstrated that substitutional level in the sol-gel derived Y3?x LnxFe5O12 (Ln = La, Ce, Pr and Nd) systems depends very much on the nature of lanthanide element. For example, the 25% substitution of Y by La small amount of side perovskite LaFeO3 phase have formed. With increasing substitutional level of La the amount of perovskite phase also increased and, consequently, the amount of garnet phase monotonically decreased. In the case of Y3?xCexFe5O12 system, the formation of monophasic garnet did not proceed in whole substitutional range. On the other hand, the monophasic Y1.5Pr1.5Fe5O12 and Y1.5Nd1.5Fe5O12 garnets have been synthesized using sol-gel chemistry approach. Only negligible amount of perovskite phase was formed in the case when 75% of yttrium was replaced by praseodymium. However, in the case of neodymium the synthesis product with such substitutional level still was monophasic garnet. The SEM analysis results revealed that the most particles were formed in the range of 0.5–40 μm showing rather broad particle size distribution. Magnetic properties were also determined by magnetization measurements.

    Effect of extrusion temperatures on the microstructures, mechanical properties and thermal properties of PM Al-20Si alloy

    Ding C.Yu P.
    9页
    查看更多>>摘要:? 2022 Elsevier B.V.Al-20Si alloy is fabricated by extruding pre-alloyed powder at different temperatures ranging from 350° to 550°C. Morphologies of the Si phase, mechanical properties and thermal properties of the alloy are influenced by extruding temperature. The alloy extruded at 350 °C mainly contains fine eutectic Si. Although its fine structure imparts high strength to the alloy, it is not stable in high-temperature CTE test and tends to agglomerate into large Si lumps due to Oswald ripening effect, therefore offsetting the restriction effect of Si on the thermal expansion of Al and thus increasing the CTE of the alloy. In contrast, the alloy extruded at 550 °C exhibits primary Si phase, which is large in size and more stable in the CTE test. Moreover, it has in-situ formed amorphous/δ * - Al2O3 at the grain boundaries which reduces the CTE of the alloy further. As a result, the alloy fabricated at 550 °C exhibits the best combination of thermal properties (i.e. TC 184.5 Wm?1K?1 and CTE 20.9 ×10?6 K?1 at 400 ℃).

    Fan-shape Mn-doped CoO/C microspheres for high lithium-ion storage capacity

    Cui M.Chen X.Wang Z.Tao S....
    7页
    查看更多>>摘要:? 2022 Elsevier B.V.Cobalt monoxide (CoO) has received considerable attention because of promising applications in lithium-ion batteries (LIBs). However, nanostructured CoO anode materials still suffer from the poor conductivity and large volume change. By optimizing the morphology and introducing the proper dopants, some of the obstacles can be overcome. In this work, a fan-shape Mn-doped CoO/C microsphere (Mn-CoO/C) composite is synthesized by a one-step hydrothermal process and the electrochemical properties are evaluated systematically. The Mn-CoO composite has a flabellum structure with a length of 5–10 μm assembled on nanosheets with a size of 20–50 nm. The interlayer spacing is 30–100 nm and the Co to Mn ratio is 8:1. The Mn-CoO/C electrode shows a high specific capacity of 741.2 mAhg?1 at 0.1 C as well as good cycling stability. To demonstrate the practicality of the electrode materials, the lithium-ion battery shows a capacity of 726.4 mAhg?1 after 200 cycles. The large specific surface area and short ion/electron transfer paths lead to the excellent electrochemical performance and our results reveal a simple and practical strategy to improve the lithium storage capacity of LIBs.

    Microstructure and mechanical properties of a novel functionally graded material from Ti6Al4V to Inconel 625 fabricated by dual wire + arc additive manufacturing

    Zhang G.Cai Y.Han J.Tian Y....
    11页
    查看更多>>摘要:? 2022The functionally graded material (FGM) from Ti alloy to Ni alloy has potential applications in the hostile environments including high temperature and strong corrosiveness. For instance, the aerospace or nuclear industry. However, it is difficult to fabricate a FGM by the traditional methods. In this study, the dual wire + arc additive manufacturing technology was used to manufacture a functionally graded material thin-walled component transitioned from Ti6Al4V to Inconel 625 using Ti6Al4V and Inconel 625 wires, with 10% composition change per gradient. The results show that the elemental distribution of the FGM component presented an excellent linear relationship with an increased component height. The FGM microstructure was changed from the bottom to top: α-Ti + β-Ti → α-Ti + NiTi2 → NiTi2 → NiTi2 + NiTi → NiTi + Ni3Ti + (Cr, Mo) + Laves → Ni3Ti + (Cr, Mo). The microhardness of the thin-walled component ranged from 370 HV0.2 to 843.4 HV0.2. The average ultimate compression strength and strain of vertical samples were 1390.25 MPa and 10.96%, and the fracture was a brittle cleavage one because of the formation of hard and brittle NiTi2.

    Low-temperature accelerated sintering of high-performance oxide dispersion strengthened ultrafine grained Mo alloy

    Dong Z.Ma Z.Yu L.Chen S....
    11页
    查看更多>>摘要:? 2022 Elsevier B.V.As a promising route to prepare ultrafine-grained or nanocrystalline materials, powder metallurgy has long been used to produce some metal materials with desirable microstructure. However, the challenges of rapid grain growth and torpid densification during this process always frustrate the endeavor. Especially, for the oxide dispersion strengthened (ODS) alloy, although grain growth is suppressed greatly by the traditional oxide addition, the densification of metal matrix is also hindered, especially at low temperature. To overcome such limitation, exploring a kind of oxide that can be used as both grain growth inhibitor and sintering accelerator for metal matrix will be significant. In this work, it is found that accelerated sintering can be achieved in Mo-ZrO2 system at low temperature. The kinetic simulation results indicate that although the volume diffusion has been found to be the dominant sintering mechanism for Mo-ZrO2 system, a significant contribution from grain boundary diffusion is also identified, which is the essential mechanism behind the accelerated sintering of this system at low temperature. Besides, the grain boundary migration also can be significantly restricted by the intergranular ZrO2 particles. After sintering at only 1480 °C in the absence of external pressure assistance and subsequent hot forging, nanocrystalline microstructure with an average grain size of 480 nm can be obtained. The ZrO2 second-phase particles are uniformly distributed at grain interior and grain boundaries, enhancing the recrystallization temperature and microstructural stability of metal matrix, which renders the prepared Mo-ZrO2 alloy a stable high-strength performance characteristic even under high temperatures.

    Optimizing strength and ductility in 7150 Al alloys via rapid electropulsing cyclic heat treatment

    Chen K.Zhan L.Xu Y.Ma B....
    9页
    查看更多>>摘要:? 2022 Elsevier B.V.In this work electropulsing cyclic heat treatment (ECHT) process was used to control the microstructure and optimize the mechanical properties of 7150 Al alloys. The results show that the 7150 Al alloys can achieve high strength and excellent ductility properties after only 10 times ECHT for 1 h. Moreover, the measured ductility properties of the 7150 Al alloys are superior to that of the as-received samples. The main reason is that ECHT accelerates the homogeneous nucleation of coherent Guinier-Preston (GP) zones and fine ?' precipitates, and increases dislocation density. The quantitative analysis results indicate that the strengthening mechanisms are mainly dependent on precipitation Orowan strengthening and dislocation strengthening. In addition, the effect of ECHT on the rapid nucleation of precipitates is also discussed in this study. Compared with the traditional heat treatment, the ECHT is a high-efficiency method, which can potentially be applied to age-hardening Al alloys and open new avenues for obtaining high-performance materials.

    Effect of temperature on shear properties of Sn-3.0Ag-0.5Cu and Sn-58Bi solder joints

    Jeong M.-S.Lee D.-H.Yoon J.-W.
    15页
    查看更多>>摘要:? 2022 Elsevier B.V.Microelectronic devices with advanced capabilities, such as multi-functions, high input/output densities, and high capacities, have recently found extensive application in areas such as servers, big data, data centers, IoT, and supercomputing. Owing to the diverse operating conditions of these applications, the reliability of the microelectronic packaging depends on the integrity of the soldered joints at various (high) operating temperatures. In this study, the mechanical shear properties of Sn-3.0Ag-0.5Cu (SAC305) and Sn-58Bi (in wt%) solder joints were studied using a ball shear test at various temperatures on substrates with two types of surface finish: organic solderability preservative (OSP) and electroless nickel-electroless palladium-immersion gold (ENEPIG). The joint strength, force-displacement curve, and fracture energy were measured and calculated for each joint, and the correlations between solder alloys, operating temperatures, and joint mechanical behaviors were revealed. In the case of the SAC305 solder, regardless of the substrate, with increasing temperature, the shear force decreased, fracture distance increased, and the fracture energy decreased. In addition, the fracture was predominantly ductile. In the case of the Sn-58Bi solder, with increasing temperature, the shear force decreased, and the fracture distance increased slightly and then decreased (OSP substrate) and kept constant then decreased (ENEPIG substrate), and the fracture energy decreased. Although ductile fracture occurred at low temperatures, the brittle fracture proportion gradually increased as the temperature increased. Further, the microstructure significantly affected the mechanical properties and fracture behavior of the SAC305 and Sn-58Bi solder joints.

    Microstructure and properties of β-TCP / Zn - 1Mg composites processed by hot extrusion combination of multi-pass ECAP

    Xu Y.Zhang Z.Liu D.Zhao Y....
    15页
    查看更多>>摘要:? 2022 Elsevier B.V.To further improve the comprehensive service performance of Zn, hot extrusion combined multi-pass equal channel angular pressing route were applied to process Zn-1(wt%)Mg alloy and 1(vol%)β-TCP/Zn-1Mg composites. As-cast cylinders specimens with a diameter of 60 mm were finally processed to the ECAP-processed specimens with the dimensions of 15 mm × 15 mm × 120 mm. The evolution and corresponding mechanism of the microstructure, mechanical properties, corrosion behavior, and biocompatibility of 1β-TCP/Zn-1Mg composites and Zn-1Mg components were systematically investigated. As a result, compared with Zn-1Mg alloy, the grain refinement effect of ECAP was enhanced in the 1β-TCP/Zn-1Mg composites with exact the same ECAP conditions. Among all the experimental specimens, the minimum average grain size of 3.0 ± 0.3 μm was achieved in 1β-TCP/Zn-1Mg composites processed by 8 ECAP passes. With the increase of ECAP processing times, the texture strength increased, and the texture direction changed to be (0 0 0 1) base plane parallel to TD-axis. Consequently, the 1β-TCP/Zn-1Mg composites after 8 passes of the ECAP process exhibited the highest compressive yield strength (CYS) of 288.05 ± 6.87 MPa and an elongation greater than 50%. Moreover, these composites also showed a moderate degradation rate of 0.04496 mm·y?1 in the simulated body fluid solution. The in vitro cytotoxicity and cytocompatibility evaluation revealed that both ECAP-processed Zn-1Mg alloy and 1β-TCP/Zn-1Mg composites showed non-cytotoxicity to MC3T3-E1 cells, and the addition of β-TCP could improve the biocompatibility of the experimental materials. Above all, the combination of hot extrusion and ECAP should be a useful route to obtain biodegradable Zn-based materials with excellent comprehensive service performance as orthopedic implants. The 1β-TCP/Zn-1Mg composites, which were processed by hot extrusion and subsequent 8 passes ECAP, exhibited the highest CYS, moderate degradation rate, and good biocompatibility, should be a promising candidate for the application of bone repair and bone replacement.