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Quick Search     Adv Search   2022 Vol. 32, No. 02 Published: 2022-04-10   1 Research status and prospects of selective laser melting forming of aluminum alloy and composites Hot! XIAO Zhiyu，TANG Hao，XI Xiaoying，ZHANG Jiantao DOI: ：10.13228/j.boyuan.issn1006-6543.20210176 Aluminum alloy and aluminum matrix composite materials perfectly fit the requirements of lightweight parts in the industrial field for their high specific strength. With the development of modern industrial, more and more aluminum alloy parts with complex structure are required in various field, but traditional processing methods are difficult to prepare. Selective laser melting technology can realize the near-net forming of metal parts, it can also be used to prepare the complex shape and structure of parts. It has a wide application prospect in aerospace, advanced transportation and other industrial fields. In this paper, the research on aluminum alloy and aluminum matrix composites at home and abroad in recent years is summarized, and focus on the microstructure, mechanical properties and corresponding strengthening mechanism of several typical aluminum alloy systems and composite processed by selective laser melting. Finally, the present problems and future development trends are summarized. 2022 Vol. 32 (02): 1-12 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 13 Study on Cu/graphite composite powders by magnetic suspension impact grinding Hot! MU Hongliang，FENG Liu，WU Liqing，LIU Zhichao，ZHENG Fei，ZHAO Zengdian DOI: ：10.13228/j.boyuan.issn1006-6543.20210078 Cu/Graphite composite powders are widely used in the field of electrical contact components due to their excellent electrical conductivity and thermal conductivity, high mechanical strength and excellent self-lubrication performance. However, the solid solubility of graphite in Cu is limited, and the density difference between the Cu and graphite is large, so it is hard to get the uniform Cu/Graphite composite powders. At present, high-energy ball milling is one of the main methods to prepare composite powders, which has simple process and low cost, while its efficiency is low, and the interfacial strength of Cu and graphite is weak. Therefore, it is necessary to find a new technology to prepare Cu/Graphite composite powers with uniform size and high interfacial strength. A new magnetic suspension impact grinding technology was proposed for preparing Cu/Graphite composite powders. The effects of grinding time and graphite contents on the microstructure of composite powders such as particle size and graphite defects were investigated. The combined state of Cu/Graphite composite powders was discussed, and the efficiency of magnetic suspension impact grinding and high energy ball milling were compared and then analyzed. The results show that the particle size of the Cu/Graphite composite powders decreases first and then increases with the extension of grinding time. The addition of graphite is helpful to refine the composite powders; the Cu particles in the composite powders are face-centered cubic nano particles with micro strain, part of the C atoms in the graphite are solid dissolved in the lattice spacing of Cu, and the particle surfaces are wrapped by a thin graphite layer. Compared with the high-energy ball milling method, the magnetic suspension impact grinding technology possess the advantages of much higher efficiency, and the obtained composite powders distribute evenly in size, also have better bonding interfaces between Cu and graphite particles. The composited powders with 10% graphite contents present smaller size and the higher uniformity as the grinding time is 3 h. 2022 Vol. 32 (02): 13-20 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 21 Study on injection molding process of complex parts for iron-based alloys Hot! ZHOU Fen，LUO Meng，XIE Min，BAO Jinxiao，GAO Jianquan，SONG Xiwen DOI: 10.13228/j.boyuan.issn1006-6543.20200302 The iron-based alloy part with complex shapes and thin walls could not be prepared by conventional methods. In this paper,the iron-based alloy part made of Fe-Ni-Co-Mo-Ti alloy was produced by powder injection molding. Oxides were used as raw materials, and high-density polyethylene (HDPE), polyethylene-ethylene ethyl acetate copolymer (EVA), paraffin (PW) and stearic acid (SA) were used as binders to study the optimal binder composition and optimal solids content for feeding. On this basis, the optimal process of n-heptane degreasing and the influence of thermal degreasing atmosphere on carbon and oxygen content in products were studied. The composition of the optimized binder system was determined by testing the relationship between the torque and time of feedstock, and combining with the quality of the green parts measuring. The optimal solids loading of feedstock was determined by torque rheometer. The microstructures of the mixed powder, the green part, the solvent-debound part, and the thermal-debound part were observed using a field emission scanning electron microscope (FESEM) and scanning electron microscopy (SEM). The mixing torque was recorded using a torque rheometer (ZJL-200) at 115 ℃ and 45 r/min. The contents of carbon and oxygen residues in the sintered samples were measured by a carbon/ sulphur determinator (CS-8810) and an oxygen and nitrogen analyzer (ON-2000), respectively. The influence of different debinding atmospheres on the carbon and oxygen residues in the sintered samples were also investigated. The densities of the sintered samples were tested using Archimedes’method. The results show that the feedstock with the binder composition of 15% HDPE-75% PW-8% EVA-2% SA and with the optimum solid content of 50% has a good fluidity and the green parts have high strength. The optimum condition for the binder removal of n-heptane is 80 min-40 °C. The thermal debinding atmosphere affects the carbon and oxygen content of the product. When debinding in hydrogen atmosphere, the residual carbon content is high, the residual oxygen content is low, and the argon atmosphere is opposite. The product sintered in hydrogen atmosphere has an iron phase and has a high density. Complex parts of Fe-Ni-Co-Mo-Ti base alloy with complex shapes and thin walls can be prepared by powder injection molding technology with the binder system of 15% HDPE-75% PW-8% EVA-2% SA and the optimal solid content consisting of 50%. 2022 Vol. 32 (02): 21-26 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 27 Effect of rare earth rich alloy addition on microstructure and magnetic properties of sintered (MM, PrNd) -Fe-B Hot! XU Jiyuan，XU Yafen，ZHOU Mingge，CHEN Hongsheng，HAN Rui，DONG Shengzhi DOI: 10.13228/j.boyuan.issn1006-6543.20220012 In this paper, sintered (MM, PrNd)-Fe-B magnets containing mischmetal（MM）were prepared by conventional powder metallurgy process, and the effects of rare earth rich alloy on the microstructure and magnetic properties of the magnets were studied. The aggregation of La and Ce in the grain boundary of MM7 (PrNd)24Fe74.99B1.01 magnet without rare earth rich alloy, can be eliminated by adding 6% of (PrNd)41Fe57.99B1.01 rare earth rich alloy, and the coercivity of magnet can be increased from 11.15 kOe to 11.98 kOe. Microstructure analysis shows that, after adding rare earth rich alloy, there is a double main phase structure in the magnet. Pr and Nd in (PrNd)2Fe14B are replaced by La and Ce, with La and Ce in (MM, PrNd)2Fe14B being replaced by Pr and Nd. The coercivity of the magnet is improved by the uniform distribution of La and Ce in the grain boundary and the dual main phase structure. 2022 Vol. 32 (02): 27-33 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 34 Effect of carbon on microstructure and properties of Al2CoCrCuFeNi high entropy alloy Hot! YANG Hengzhe，ZHANG Senming，SUN Fenger，LIU Heping DOI: 10.13228/j.boyuan.issn1006-6543.20210063 High entropy alloy has the lattice distortion effect, sluggish diffusion effect,“cocktail”effect and the high entropy effect, which makes it easy for high entropy alloy to obtain stable solid solution structure, nanostructure and even amorphous structure. Therefore, the alloy has many excellent properties, such as high strength, excellent hardness, outstanding wear resistance, good temperature stability, corrosion resistance, fatigue resistance and magnetic properties. Powder metallurgy is one of the most common techniques for preparing high entropy alloys, which can obtain bulk alloys with fine grains and uniform structure. In this paper, Al2CoCrCuFeNi and Al2CoCr- CuFeNiC0.02 high entropy alloy had been designed. The influence of C on the microstructure and properties of the alloy was studied. Meanwhile, the strengthening mechanism of the alloy was discussed based on the calculation of theoretical hardness value. In this paper, mechanical alloying and powder metallurgy were used to obtain the high entropy alloy, the powdered alloy was synthesized by high-energy ball milling, then the bulk alloy was formed after sintering. The microstructure and properties of the alloy were characterized by X-ray diffraction, metallographic microscope and Vickers hardness tester. Through the model, the phase composition and hardness of the alloy were predicted and verified. At the end of the paper, the strengthening mechanism of the high entropy alloy is given. The Al2CoCrCuFeNi and Al2CoCrCuFeNiC0.02 high entropy alloys are successfully prepared by powder metallurgy method. After mechanical alloying, some elements are not completely dissolved into the solid solution to form a solid solution alloy, but through the subsequent sintering, a solid solution alloy with FCC+BCC or FCC+ ordered BCC(B2) crystal structure is obtained. According to XRD results，BCC and B2 phases are the main phases of Al2CoCrCuFeNi and Al2CoCrCuFeNiC0.02 high entropy alloys, respectively. This is consistent with the results calculated by the solid-solution formation rule for high entropy alloy. The hardness of alloys is 208 HV and 328 HV, respectively, which is very close to the strength calculated by the model then is converted to hardness. The addition of carbon has a significant contribution to the strength of the high entropy alloy, which makes the hardness increase about 58% compared with the alloy without carbon. The high entropy alloy prepared in this paper has a favorable composite strengthening mechanism, and the strengthening derives from the comprehensive contribution of multiple factors. 2022 Vol. 32 (02): 34-39 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 40 Microstructure and optical properties of spinel ZnAl2-xFexO4 nanoparticles Hot! WANG Jinman，ZHANG Kecheng，MAQiang，WANG Jian，LU Qiang，WEI Zhiqiang DOI: 10.13228/j.boyuan.issn1006-6543.20210050 Because of its unique crystal structure and excellent physical and chemical properties, ZnAl2O4 has a broad application prospect in magnetic storage devices, catalysts, high temperature ceramics, laser and fluorescent substrate materials, sensors and optoelectronic devices. The microstructure and optical properties of ZnAl2O4 binary metal oxide were investigated by doping the transition metal Fe ions into the octahedral position.Fe- doped ZnAl2-xFexO4 nanoparticles (x=0, 0.025, 0.05 and 0.10) were synthesized by hydrothermal method and heat treatment. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoemission spectroscopy (XPS), UV-Visible spectrum (UV-Vis), photoluminescence (PL) and Fourier transform infrared spectroscopy (FT-IR) were used to study the microstructure of Fe doped samples and optical properties. XRD patterns show that the structures of all ZnAl2-xFexO4 samples are similar, and Fe doping into ZnAl2O4 lattice does not change the structure of ZnAl2O4 nanoparticles. The crystal plane of the sample is obtained by using the jade software parameters, spacing and grain size, with the increase of Fe doping concentration, crystal grain size decreases, Fe doping has a regulating effect on grain size. In order to prove that Fe3 + successfully replaced Al3+ as dopant into ZnAl2O4 matrix without forming impurity enrichment phase, FE-SEM was used to scan the distribution of elements in ZnAl1.90Fe0.10O4 samples. The samples are mainly regular spherical, relatively uniform particle size, with an average particle size of less than 50 nm. The chemical composition and elemental chemical states of ZnAl2-xFexO4 were studied by X-ray photoelectron spectroscopy. Ultraviolet-visible absorption spectra shows that doping samples have absorption in the visible area, moreover with the increase of doped with iron content in sample, the absorption peak intensity in the ultraviolet and visible light wavelength region increases significantly, Fe doping in the visible light range near 470 nm produce an additional absorption peak, the octahedral coordination of iron ion d-d transition. This indicates that Fe ions replace Al ions and exist as Fe+3 in octahedral crystals. The band gap of the sample is calculated to be less than the corresponding pure ZnAl2O4 (3.8 eV). The band gap of doped samples decreases with the increase of Fe ion concentration. This phenomenon is attributed to the change of band structure caused by the sp-d exchange between band electrons and the local d electrons of Fe ions replacing Al ions. FT-IR results show that the spinel structure is still present in Fe-doped ZnAl2- xFexO4 samples. PL spectra show that, compared with pure ZnAl2O4, the luminescence intensity of ZnAl2- xFexO4 samples decreases sharply with the increase of Fe ion concentration, and quenching phenomenon occurs. The chromaticity diagram shows that the chromaticity distribution of the sample can be controlled by controlling the doping concentration, and the peak value decreases regularly with the increase of the doping concentration, indicating that ZnAl2- xFexO4 nanoparticles have excellent luminescence ability. The microstructure and optical properties of ZnAl2O4 can be effectively changed by preparing transition metal Fe ions doped into the octahedral position of binary metal oxide ZnAl2O4, which provides reference value for the subsequent research and production and application of ZnAl2O4. 2022 Vol. 32 (02): 40-46 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 47 Study on microstructure and properties of high boron stainless steel with 3.29% boron content Hot! PEI YanBin，WANG TieJun，GE QiLu，CHEN Jin，QU XuanHui DOI: 10.13228/j.boyuan.issn1006-6543.20210046 The objective of the study was to prepare the borated stainless steel (BSS) containing with 3.29% boron, to test BSS powder morphology and eutectic melting points, and observe phases, microstructure, elemental distribution and mechanical properties of BSS alloy. These characteristics were compared with two grades of BSS alloy with lower boron content (0.29% and 1.86%) which correspond to standard A887 304B and 304B7 respectively issued by American Society of Testing Materials (ASTM). The Fe-Cr-Ni austenite steel powder with boron was obtained by atomization equipment. Fe-B, Fe-Cr and other raw materials were put into the melting furnace to melt and then were ejected to make the powder. The morphology of the BSS powder was observed by scanning electron microscope (SEM) and the eutectic melting point was analyzed by differential scanning calorimetry (DSC). The gas atomization powder obtained was passed through the 74 μm sieve. The powder was placed in the capsules. Filled with BSS powder, the capsules were heated to 500 °C in the atmospheric oven and degassed to 10?3 Pa to reduce oxidation of the powder. The capsule was placed in the hot isostatic pressing (HIP) furnace and then heated up, elevated pressure and held at sintering temperature and maximum pressure (110 MPa) for 2 h. Coupons of three BSS alloys were evaluated by quantitative X- ray diffraction (XRD) phase analysis. Microstructures were observed by SEM and energy-dispersive spectroscopic (EDS) analysis. Strength and ductility of specimens were tested according to Chinese Standard GB/T 228.1. The eutectic liquid phase point of BSS with 3.29% boron occurs at 1 181.4 °C tested by DSC. The BSS alloy with 3.29% boron prepared by PM comprised two main phases: the cubic austenite phase is 66 %; the orthorhombic Fe1.1Cr0.9B0.9 boron phase is 34 %. The boron phase grains of BSS with 3.29% boron have irregularly shaped grains, many of which are already in contact and joined together, while the grains of the low content boron BSS alloys have the regular shape and are separated from each other. The element boron fluctuates between 9.0% and 16.6% in the boron-containing phase of BSS, so the boron distribution of BSS is uneven. The BSS containing 3.29% boron have the tensile strength of 900 MPa and the elongation of only 1.0%, while 304B7 BSS have tensile strength of 720 MPa and elongation of 13.0% and 304B sample have tensile strength of 770 MPa and elongation of 20.5%. The tensile strength of BSS with lower boron content below 2.25% is similar, but elongation decreases with the increase of boron content; however, the strength of BSS with 3.29% boron is greater than that of low boron alloys by more than 100 MPa, but elongation decreases to only 1%. BSS alloys consist of two phases, the boron-containing phase content increases as the boron content of the alloy increases. As the boron content increases, the grains of the boron-bearing phase become irregular and the connections between grains increase. The BSS alloy containing 3.29% boron is brittle material. 2022 Vol. 32 (02): 47-51 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 52 Preparation and properties of TiB2-HFC composite tool material Hot! ZHANG Fengguo，FAN Xiaowen DOI: 10.13228/j.boyuan.issn1006-6543.20200029 The effects of the content of reinforcement phase, the type and content of metal bonding phase on the phase composition, microstructure and mechanical properties of TiB2 based cutting tools were studied. The results show that TiB2 based cutting tools with different HfC content are mainly composed of TiB2, HfC, a small amount of Ni and MoNi4 phases; in the sintering process, Ni will react with Mo to form a small amount of MoNi4 phases. When the HfC content reaches 20%, TiB2 based cutting tools have the highest bending strength, fracture toughness and high hardness. Compared with the samples with pure Ni as the metal phase, pure Co as the metal phase and Ni + Mo as the metal phase, the TiB2 and HfC phases in the samples with Ni and Co as the metal phase have more uniform distribution and better wetting effect. At this time, the bending strength, fracture toughness and hardness of TiB2 based tool materials are 834 MPa, 9.50 Mpa·M1/2 and 22.92 Gpa, respectively, which has the best comprehensive mechanical properties. 2022 Vol. 32 (02): 52-56 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 57 The influence of pore forming agent content on the properties of porous metal materials Hot! WANG Yaohui，CHENG Kai，CAO Buyuan，WANG Ye DOI: 10.13228/j.boyuan.issn1006-6543.20200262 Using 316L stainless steel powder and PMMA powder as raw materials, porous stainless steel plate was prepared by powder sintering method. The pore diameter, permeability coefficient and microstructure of the stainless steel plate were characterized by SEM、bubble pressure aperture distributing instrument and air permeability measuring instrument. The results show that with the decrease of PMMA content, the thickness of porous metal sintering plate decreases, the distance between metal particles decreases after sintering, and the sintered trap is easier to be formed. The best sintering temperature is 1 100 ℃. When the PMMA content is the lowest, the ventilation value reaches the minimum value of 63 m3/(m2 ·kpa·h). and the average pore diameter decreases to 2.79 μm. 2022 Vol. 32 (02): 57-61 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 62 Effect of reaction conditions on the properties of Ni0.5Co0.2Mn0.3(OH)2 Hot! LIU Jiying，WU Jing DOI: 10.13228/j.boyuan.issn1006-6543.20200148 Abstract：This paper focuses on the effects that the concentration，temperature，PH and reaction time of nickel manganese cobalt （NMC）sulfate solution on the small size products’tap density, specific surface area and sulfur content of Ni0.5Co0.2Mn0.3(OH)2 through co-precipitation. The results show that whether the concentration, temperature and PH of NMC sulfate solution is too high or too low, they are not good for the production quality control(PQC). When the PH is between 12.00 and 12.20, the concentration is 2.5 mol/l, the temperature is between 35 and 40 ℃, and the reaction time is 30 hours,small size Ni0.5Co0.2Mn0.3(OH)2 products with high performance can be synthesized. 2022 Vol. 32 (02): 62-66 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 67 Study on the surface coating and properties of carbide cutting tools Hot! GUO Yanlei，WANG Xuke，LU Zhenfa DOI: 10.13228/j.boyuan.issn1006-6543.20200088 AlCrN, TiAlSiN and TiAlCrN coatings were prepared on the surface of cemented carbide cutting tools by magnetron sputtering. The surface morphology, coating thickness, surface roughness, hardness, adhesion with matrix and wear resistance of the three coatings were compared and analyzed. The results show that there are micro pits with different sizes and white particles on the surface of three kinds of coatings of cemented carbide cutting tools, while the thickness of TiAlSiN coating is relatively small and the roughness is relatively large; the microhardness of the three kinds of coatings is obviously higher than that of the matrix, and the order of the microhardness from high to low is: AlCrN > TiAlCrN>TiAlSiN; The adhesion of AlCrN, TiAlSiN and TiAlCrN coatings to the substrate were 44, 39 and 48 N, respectively. The friction coefficient of the three kinds of coating samples is smaller than that of the uncoated samples, and the wear rate under the same load is significantly smaller than that of the matrix, and the wear rate of the coating is from small to large as AlCrN 2022 Vol. 32 (02): 67-71 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 72 Microstructure and tensile properties of carbon fiber reinforced ZL109 alloy for building Hot! QIN Chunli，FU Hao，BAO Anqing DOI: 10.13228/j.boyuan.issn1006-6543.20200104 The fiber reinforced Cf/Al matrix composites with a volume ratio of 50% were prepared by vacuum pressure impregnation on the surface of aluminum-magnesium ZL109 alloy using M40J carbon fiber as reinforcement material. The structure and mechanical properties of Cf/Al based materials were studied by means of experimental tests. The results show that the density of Cf/Al based materials decreases to a certain extent compared with that of the matrix alloy to achieve the effect of weight reduction. After infiltration treatment, no distortion occurs in the braid prefabricated body, and the fiber bundle gap is closely filled with the matrix metal.Some micropores are formed and microcracks are formed in the fiber's partial location, which cause great distortion after fiber infiltration. Interfacial reaction between C fiber and Al matrix appears in Cf/Al substrate. Brittle fracture occurs when the composite is stretched at room temperature, and the fiber and matrix are tightly bonded in the fracture zone.Increasing the tensile temperature results in a more uneven fracture structure, a large number of fibers are pulled out, and a fracture of shear failure type is formed. 2022 Vol. 32 (02): 72-76 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 77 Progress in microstructure and properties of AZ91 magnesium alloy based on alloying Hot! SUN Li，CUI Xiaoming，BAI Pucun，DU Zhaoxin，WANG Zhengguang，LIU Yonghong DOI: 10.13228/j.boyuan.issn1006-6543.20210039 Magnesium alloys, which are the lightest engineering structural material, have been more-widely used in various industries, such as transportation, aerospace, computers, home appliances, communications and medical care, etc., owing to their desired performance of low density (~1.74 g/cm3), high specific strength, high specific stiffness, excellent casting, good electromagnetic shielding, damping, biocompatibility, weldable and machinable, and so on. Magnesium alloys have been honoured as the 21st century green engineering materials by many scientists and engineers. However, our country is still at the level of a large country of magnesium raw material, and the majority of magnesium resources are exported to other developed countries as raw materials at very low prices. Therefore, it is of great significance to carry out in-depth research on magnesium alloy and its products, so as to transform China from a big country of magnesium raw materials into a powerful country of magnesium alloy products, and promote the transformation of resource advantage into economic advantage. In addition, compared with forged magnesium alloy, cast magnesium alloy, in which 90% magnesium alloy is prepared by the casting method, has been widely used in many fields due to its low production cost and mass production. Up to date, the most representative cast magnesium is AZ91, and it has a market share of more than 50%. Furthermore, the microstructure of as- cast AZ91 magnesium alloy consists of dendritic α- Mg solid solution, net- like β- Mg17Al12, Mg2Si and Al8Mn5, so the mechanical performace is lower than that of aluminum alloys. Meanwhile, the magnesium element is easy to be corroded and out of operation in harsh environment because it is very active and its electrode potential s very low (about -2.36 V), so the corrosion of magnesium alloy restricts its extensive application and industrialization. Among a lot of methods, alloying is one of the effective methods to improve the microstructure, refine grain size and enhance mechanical property and corrosion resistance of AZ91 magnesium alloy. In the paper, the effects of single alloying (such as As, Ca, Sm, Zr, Nd, Sc, Y, CaO, etc.), composite alloying (such as Ca-Y, Nd-Ca, Ce-La, etc.) and master alloy (such as Mg-Al-C, Al-TiB2, etc.) on the microstructure, mechanical property and corrosion resistance of AZ91 magnesium alloys are reviewed and analyzed. The current results shown that the beneficial effects of composite alloying are the most significant, but there is no theoretical basis to direct the doping amount. Therefore, in order to provide reference for the development of high-performance AZ91 magnesium alloy, it is suggested to develop the corresponding composite alloy system based on material genetic engineering and reveal its mechanism, and the mapping relationship between alloying element content and microstructure, properties of AZ91 magnesium alloy should be disclosed in the future. 2022 Vol. 32 (02): 77-83 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 84 Research progress on Ti-6Al-4V alloy prepared by selective electron beam melting Hot! LIU Min，GUO Yu，ZHEN Zhen，LONG Xuehu，WANG Qiangbing DOI: 10. 13228/j. boyuan. issn1006-6543. 20210028 Titanium and titanium alloys are widely used in aerospace, biomedical and other fields because of their high specific strength, corrosion resistance, and good biocompatibility. Selective electron beam melting (SEBM) is one of powder bed fusion additive manufacturing technology developed in recent years. It has the characteristics of high energy density, good production efficiency, low stress, and clean in a vacuum environment. Thus, the titanium alloys prepared by SEBM technology has become a research hotspot in academia and engineering. This article summarizes the research progress of Ti-6Al-4V alloy prepared by SEBM technology, focusing on the analysis of defects, microstructure and mechanical property, and finally prospects the development and application of SEBM technology. The research progress of SEBM fabricated titanium alloy is summarized to provide reference for its application in related fields. This article focuses on the analysis of defects, microstructure and mechanical property of Ti- 6Al- 4V alloy prepared by SEBM technology, and finally prospects the development and application of SEBM technology. In the SEBM manufactured Ti-6Al-4V alloy, there are two kinds of defects, irregularly shaped pores (with unfused particles) and spherical holes. The columnar crystals, acicular α' martensite structure and massive phase are obtained in the titanium alloy, and some methods are used to transform these microstructures into α+ β lamellae, eliminate columnar crystals. The mechanical properties of Ti- 6Al- 4V alloy fabricated by SEBM are anisotropic, and strength of the as-built alloy in the vertical direction are higher than those in the horizontal direction, and the elongation in the vertical direction is higher than that in the horizontal direction. There are a large number of columnar primary β grains in Ti-6Al-4V titanium alloy prepared by SEBM, which are parallel to the construction direction. The microstructure of the alloy consists of acicular α' martensite, massive αm and layered α-β. Thin layer of α and β phase follows the Burgers orientation relationship, namely the [111]//[ 21ˉ1ˉ0 ]，(110)//(0002)， and [111]//[12ˉ13ˉ]，( 01ˉ1ˉ)//( 01ˉ11). The β phase and α phase of Ti-6Al-4V alloy have strong texture, and the β phase has strong {100}<001> texture. Mechanical properties of alloys are anisotropic and fine lamellar α- β structure improves mechanical properties of alloys. 2022 Vol. 32 (02): 84-89 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 90 Research status of plasma rotating electrode atomization technology and powder particle size control Hot! YANG Xingbo，ZHU Jilei，CHEN Binke，FENG Zhihua，LI Xiaohui DOI: 10.13228/j.boyuan.issn1006-6543.20210047 This article introduces the basic principles and powder characteristics of the plasma rotating electrode atomization technology (PREP) preparation of spherical metal powders. The classification, characteristics and equipment status of the existing plasma rotating electrocle atomization technology are reviewed. Based on the introduction of the crushing mechanism of the existing PREP technology and the powder morphology control strategy, the importance of powder particle size prediction and the particle size prediction model of the existing PREP powder are analyzed. The shortcomings of the existing model are analyzed, and the development direction of the PREP technology research is prospected. 2022 Vol. 32 (02): 90-95 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 96 Development status of the preparation of nickel-based superalloy spherical powder Hot! CHEN Xi，WANG Xiaoyu，LIU Qi，YANG Ziming，BO Xinwei，WANG Yanhui DOI: 10.13228/j.boyuan.issn1006-6543.20200207 The preparation methods of nickel- based superalloy spherical powder mainly include plasma rotating electrode powder technology (PREP), vacuum induction melting gas atomization method (VIGA), ion atomization method (PA) and electrode induction gas atomization method (EIGA) etc. This article summarizes the development status of nickel-based superalloy spherical powders, respectively introduces spherical powder preparation technology, powder screening and impurity removal, powder-related equipment and company development status, and analyzes the problems faced by nickel-based superalloy spherical powders. It hopes to provide a reference for the preparation of high-quality spherical powders. 2022 Vol. 32 (02): 96-100 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 101 Research progress in activated carbon-supported metal oxides for lowtemperature denitration Hot! RAO Jianbo DOI: 10.13228/j.boyuan.issn1006-6543.20200118 Selective catalytic reduction (SCR) with NH3 as a reducing agent is currently most effective NOx removal technology for coal-fired flue gas. Activated carbon has low denitration activity, and loading metal oxides on activated carbon can effectively improve the low-temperature denitration activity, which has been a research hotspot in recent years. This article mainly summarized the performance of low-temperature denitration of metal oxides supported on activated carbon, the advantages and disadvantages of different catalysts, and prospects its farther development of activated carbon-supported metal oxides used in low-temperature denitration 2022 Vol. 32 (02): 101-104 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 105 Progress in research on dehydrogenation of titanium hydride and manufacturing processes of spherical titanium powders Hot! LIU Yue，TANG Ruolan，JIA Shizhao，ZHENG Yan，ZHANG Deliang DOI: 10.13228/j.boyuan.issn1006-6543.20200045 Titanium powder is an important raw material for titanium and titanium alloy powder metallurgy, and dehydrogenation of titanium hydride powder is one of the key steps of the hydrogenation-dehydrogenation process for manufacturing low-cost titanium powder. Spherical titanium and titanium alloy powders are important raw materials for manufacturing high-performance complex shaped titanium and titanium alloy parts using additive manufacturing processes. The two commonly used methods for dehydrogenation of titanium hydride powder are powder metallurgy method and loose powder method. The common manufacturing processes of spherical titanium and titanium alloy powders mainly include atomization, plasma spheroidization and laser spheroidization processes. 2022 Vol. 32 (02): 105-109 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 110 Influence of ball milling parameters on CIGS target powder Hot! CHEN Yingwei，SHAO Ling DOI: 10.13228/j.boyuan.issn1006-6543.20210042 The Cu2Se、In2Se3 和Ga2Se3 raw powders of CIGS target were mixed by ball milling with different ball milling parameters. The effects of ball milling time and ball-powder-liquid ratio on particle size and microstructure of CIGS milled powders were studied by screening method of standard sieve and FESEM. The results show that with the increase of ball milling time, the leaking percentage of the sieve bottom of milled powders increases first and then decreases. However, the change of ball-powder-liquid ratio has no regular effect on the leaking percentage of the sieve bottom of milled powders. When the ball milling times are 1 h and 2 h, the agglomeration of milled powders is less, and the powders particles are basically flake structure. At 2 h of ball milling time, the particle size of milled powders is uniform. When the ball milling time is 4 h, the agglomeration phenomenon of milled powders is obvious. 2022 Vol. 32 (02): 110-114 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 )

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