锻造工艺对大规格TC17钛合金棒材组织及性能的影响

通过两种工艺锻制了Ф350mm的大规格TC17钛合金棒材,比较了经两种工艺锻制的棒材的显微组织、力学性能及探伤杂波水平。研究结果表明,在单相区采用镦拔变形使变形量大于60％,并在两相区进行拔长,使变形苗大于65％,再经840℃×2h／AC＋800℃×4h／WC＋630℃×8h／AC热处理,可得到各项力学性能均符合GJB2218A-2008标准要求且探伤杂波水平可达（b3．2mm-9～-12dB的＋350mmTC17钛合金棒材。     

Electromagnetic and microwave absorption properties of Er-Ho-Fe alloys

The Er_xHo_(2-x)Fe_(17)(x = 0.0, 0.1,0.2, 0.3, 0.4) powders were prepared by arc melting and high energy ball milling method. The influence of the Er substitution on phase structure, morphology, saturation magnetization,electromagnetic parameters was investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM), vibrating sample magnetometer(VSM) and vector network analyzer(VNA),respectively. The results show that the saturation magnetization increases and the average particle size increases with the increase of Er content. The minimum absorption peak frequency shifts towards a lower frequency region with the increase of Er content. The Er_(0.3)Ho_(1.7)Fe_(17) powder can achieve the minimum RL of-24.07 dB at 6.96 GHz with a thickness of 2.0 mm and the minimum RL is less than-20 dB at the thickness range from 2.0 to 3.0 mm. The minimum RL of Er_(0.3)Ho_(1.7)Fe_(17) is-37.26 dB at5.68 GHz and the frequency bandwidth of R-10 dB reaches about 1.2 GHz with a thickness of 2.4 mm.And the microwave absorbing properties of the composite with different weight ratios of Er_(0.3)Ho_(1.7)Fe_(17)/graphene were researched. The microwave absorbing peaks of the composite shift to lower frequency with the increase of graphene content. The values of the minimum RL of Er_(0.3)Ho_(1.7)Fe_(17)/graphene are close to-10 dB with absorbing coating thicknesses increased.     

Magnetic and microwave absorbing properties of Ce-Co-based alloy powders driven with lanthanum content

The composites of Ce-Co-based alloys doped with La content were fabricated via a vacuum arc melting method.The influences of La addition on microstructure,electromagnetic parameters,magnetic property and microwave absorbing property were measured by the corresponding equipment.The morphology characteristics manifest that all samples display sheet structure,and the average particle size of alloy powders increases with increasing La content The saturation magnetization(M_S) decreases with increasing La addition as a whole.The minimum reflection loss(RL) of La_(0.4)Ce_(1.6)Co_(17) alloy powder about-42.29 dB can be obtained about-42.29 dB at 7.84 GHz with the matching thickness of 1.8 mm,and the corresponding effective bandwidth can achieve about 2.24 GHz.In addition,the minimum RL frequency moves towards a lower frequency region as the La content increases.The minimum RL of La_(0.3)Ce_(1.7)Co_(17)alloy powder is less than-20 dB ranging from 1.2 to 2.4 mm in the whole 4-16 GHz.The maximum bandwidth can reach about 4.88 GHz at the given thickness of 1.2 mm.In general,these all indicate that the La addition is beneficial to improving the microwave absorbing performance in both effective bandwidth and absorption intensity.     

中空SiC球形纳米颗粒的合成及吸波性能

特殊结构和组成是决定电磁波吸收性能的关键因素.采用自组装技术合成碳包覆二氧化硅(SiO2@C)的球形纳米颗粒,经高温热处理后制备出中空SiC球形纳米颗粒.通过扫描电镜(SEM)和X射线衍射仪(XRD)对样品进行微观形貌分析和物相分析,采用矢量网络分析仪对样品的电磁参数进行测试,借助SiC的介电损耗以及其特殊的微观结构对...     

氧化石墨烯修饰FeSiCr纳米复合材料的微波吸收性能

采用等离子体电弧蒸发和表面改性技术制备氧化石墨烯（GO）修饰FeSiCr纳米复合材料（FeSiCr/GO），并对其微波吸收性能进行研究。拉曼光谱结果显示氧化石墨烯与FeSiCr纳米颗粒成功复合。通过TEM对FeSiCr/GO微观形貌进行表征，观察到少量絮状氧化石墨烯点缀于FeSiCr纳米颗粒表面，并且FeSiCr纳米颗粒分布在层状氧化石墨烯周围，形成氧化石墨烯修饰FeSiCr纳米复合材料。通过引入氧化石墨烯，可增加材料的电导率和界面极化能力，使FeSiCr/GO的微波吸收性能显著提升。模拟计算结果显示，在4.3 GHz处，FeSiCr/GO最小反射损耗（RL_min）可达－69.1 dB，调整涂层厚度在1.1~5.0 mm之间变化，其有效吸收频带（RL≤－10 dB）范围为2.6~18 GHz。微波吸收性能的改善可归因于阻抗匹配优化和微波损耗能力增强。      

端口驻波比对混频器变频损耗影响

设计24．1GHz集成环形混频器电路，用Aglient ADS软件进行了仿真优化，对研制混频器电路进行了性能测试和分析。测试结果表明，通过调节端1：3驻波比可以较大改善混频器的变频损耗，使混频器的变频损耗最大减少10dB左右。     

Microwave absorbing properties of NdFeCo magnetic powder

NdFeCo magnetic powder was prepared by the process of smelting,high-energy ball milling and oxidation heat treating.The effects of oxidation heat treatment and Co content on phase composition and microwave absorbing properties of NdFeCo magnetic powder were investigated by an X-ray diffractometer(XRD)and vector network analyzer.The minimum reflectivity of Nd23.25Fe36.75Co40 powder before oxidation heat treatment was-6.2 dB,and that of oxidized powder decreased to-14.0 dB.The microwave absorbing properties of NdFeCo magnetic powder could be improved effectively by oxidation heat treatment.With the increase of Co content,the Fe2O3 reduced and the Nd2O3 increased;Fe3Co7 phase appeared when the content of Co increased to 40%(mass ratio);the absorption peak was found to move towards lower frequency region first,and then it moved towards a higher frequency region.Nd23.25Fe66.75Co10 powder had better comprehensive properties in absorbing microwave in the frequency band of 3-13 GHz.The value of minimum reflectivity and absorption peak frequency,when the coating thickness(d)was 1.8 mm,were-19.7 dB and 4.8 GHz,respectively.     

2-μm GaAs HBT工艺的L型网络分布式放大器

首先对分布式放大器中L型和T型网络的频率特性进行了研究.分析表明,L型网络比T型网络在设计中具有更好的频率特性.基于稳懋半导体的2-μm GaAs HBT工艺实现了一种L型网络的分布式放大器.测试结果表明,在3～18 GHz频率范围内其增益为5.5 dB,增益平坦度为±1 dB,体现了很好的带宽性能.此外,在设计的频率范围内反射损耗S11,S22均低于-10 dB.在5 GHz时的1 dB压缩点处输出功率为13.3 dBm.芯片面积为0.95 mm2,在3.5 V电源下功耗为95 mW.     

退火处理对FeCo纳米粒子吸波性能的影响

用KBH4作为还原剂,采用化学还原法制备FeCo纳米粒子,然后在400~600℃下退火。利用X射线衍射仪、扫描电镜、X射线光电子能谱仪和振动样品磁强计对FeCo纳米粒子进行表征,用网络矢量分析仪测定其电磁参数,并分析FeCo的吸波性能,研究退火温度对FeCo纳米粒子吸波性能的影响。结果表明,化学还原法制备的FeCo纳米粒子,在厚度为5 mm时对频率为2.24 GHz电磁波的反射损耗最大,为-14.9 dB,损耗机制以介电损耗为主。随退火温度从400℃升高到600℃,FeCo纳米粒子的介电损耗逐渐减小而磁损耗逐渐增大,在400℃退火后的FeCo粒子具有最优的电磁匹配特性和最高的反射损耗,在厚度为3.55 mm时对4.48 GHz电磁波的反射损耗为-49.14 dB。     

热处理对TC11钛合金薄壁环材室温力学性能的影响

制备出规格为φ630mm/φ530mm×300mm的TC11钛合金薄壁环材.分别选用不同的固溶温度、固溶冷却方式和时效温度对环材试样进行热处理,研究热处理制度对环材室温拉伸性能的影响.结果表明:经过950℃×1h/AC+930℃×1.5h/WC+580℃×6h/AC三重热处理,可以得到室温拉伸性能满足Rm≥1100Mpa、RpO.2≥1000MPa、A≥10％、Z≥20％要求的TC11合金薄壁环材.     

水平连铸分离环碎裂的分析和改进措施

通过对Φ130mm管坯水平连铸用分离环拉坯过程碎裂的分析以及进行了分离环成分对性能影响的试验,改进了分离环的成分和连铸工艺。结果表明,当使用βSi3N4+30%BN分离环,分离环尺寸精度达到0.1mm,控制钢中N含量≤60×10^-6,O含量≤30×10^-6,反推量3～5mm时,分离环碎裂得到有效控制,月平均碎裂率由改进前的8.3%降至改进后0.3%以下。     

Microwave electromagnetic and absorbing properties of Dy3+doped MnZn ferrites

Dy3+ doped Mn-Zn ferrites Mn0.3Zn0.7Fe2-xDyxO4(x=0,0.01,0.02,0.03,0.04)were prepared by the conventional solid-state reaction.The crystal structure,surface morphology and electromagnetic properties of the calcined samples were characterized by X-ray diffraction analysis(XRD),scanning electron microscopy(SEM) and network analyzer(Agilent 8722ET).All the XRD patterns showed the single phase of the spinel-type ferrite without other intermediate when x≤0.03.The average crystallite size was about 44?56 nm.The mi...     

粉末冶金旋压无缝钨管的组织性能及使用情况

用粉末冶金法制坯,以旋压法加工无缝钨管为试样,测定了加工过程中硬度、密度和组织变化,测定了钨管的再结晶温度,并描述了钨管的实际使用情况。不同变形率下钨管的组织是:11%变形率时还有未变形的组织;66%变形率时能看到细长的烧结孔洞;77%变形率时晶粒已破碎,烧结孔洞全部消失。用于钨铼热电偶标定炉的高精度无缝薄壁钨管结果是:φ40×0.25×540mm者,在中心位置100mm范围内,1200℃、1400℃和1600℃的轴向温差分别为±1℃、±6℃和±7℃;φ30×0.25×286mm者,等温区允许误差在1377±12℃,该区长度为120mm。     

GCr15钢大方坯结晶器电磁搅拌工艺参数优化研究

摘要：为明确不同电磁搅拌条件对结晶器内钢液流动、传热行为的影响规律,对现场大方坯连铸结晶器电磁搅拌工艺参数的配置提供依据,采用ANSYS Fluent及Maxwell研究了320mm×280mm断面GCr15高碳轴承钢连铸过程中结晶器电磁搅拌工艺参数对结晶器内钢液温度场、磁场特性、注流冲击深度及液面波动的影响规律。研究结果表明,在M-EMS作用下,结晶器内钢液温度的耗散明显优于无电磁场作用工况,有利于改善结晶器内温度均匀性。注流的冲击深度随电流强度的增大而降低,而频率改变对钢液冲击深度影响不明显。当电磁搅拌电流强度一定时,随着搅拌频率增加,液面波动趋于平缓;当搅拌频率一定时,随着电流强度增加,液面波动变剧烈。对于320mm×280mm断面GCr15高碳轴承钢不同工艺进行工业试验,只改变结晶器电磁搅拌参数,从300A/2Hz调整到350A/3Hz,铸坯横截面中心碳偏析指数从1.06降低到1.01,铸坯纵截面中心碳偏析指数的平均值从0.98升至0.99,适合该钢种结晶器电磁搅拌工艺参数为350A/3Hz。     

不同方式引入CuO制备低温烧结(Bi1.5Zn0.5)(Zn0.5Nb1.5)O7陶瓷

以Bi₂O₃、ZnO和Nb₂O₅为原料,采用传统固相反应法制备（Bi_1.5Zn_0.5）（Zn_0.5Nb_1.5）O₇（BZN）陶瓷。通过CuO包覆层修饰BZN粉体表面,引入CuO助烧剂代替直接混合BZN和CuO粉体。以CuSO₄溶液为先驱体制备CuO包覆层,采用液相包覆法引入助烧剂可减少CuO的添加量,从而降低CuO对BZN陶瓷介电性能的不良影响。结果表明,当CuSO₄溶液浓度为0.5 mol/L时,可以促进陶瓷的烧结和致密化过程,经900℃烧结3 h所得BZN陶瓷介电性能最佳,介电常数（ε_r）为141,品质因数值（Q_f）为426 GHz,谐振频率温度系数（τ_f）为—357×10-6/℃（4 GHz）,皆优于固相混合法所得介电性能（介电常数为134,品质因数为287 GHz,谐振频率温度系数为—374×10-6/℃（4 GHz））。     

Er3+-substituted W-type barium ferrite: preparation and electromagnetic properties

Er3+-substituted W-type barium ferrites Ba1-xErx(Zn0.3Co0.7)2Fe16O27(x=0.00,0.05,0.10,0.15,0.20)were synthesized by polymer adsorbent combustion method.Samples were characterized by X-ray diffraction analysis(XRD),X-ray fluorescence(XRF),scanning electron microscopy(SEM)and network analyzer to investigate the relationships among Er3+concentration,crystal structure,surface mcrphology and electromagnetic properties.All the XRD patterns showed pure phase of W-type barium ferrite when x≤0.15,while the impurity phase of ErFeO3 appeared when x=0.20.The pure W-type barium ferrite showed a hexagonal flake shape.In addition,the microwave electromagnetic properties of samples were analyzed in the frequency range of 2-18 GHz.It was indicated that the electromagnetic properties were significantly improved when Er3+doping content was 0.10.The reasons were also discussed using electromagnetic theory.The optimized ferrite exhibited excellent microwave absoption performance.The maximum of reflection loss(RL)reached about-27.4 dB and RL was below-10dB at the frequency range from 8.4 GHz to 18 GHz,when the thickness was 2.6 mm.     

Ti-B25钛合金管材挤压成形数值模拟及实验研究

为了加快推动Ti-B25钛合金在舰船通信系统上的应用,利用前期构造的本构方程和热加工图优化出的工艺参数,使用DEFORM-3D有限元软件模拟了变形温度900℃、应变速率0.1 s^-1工艺参数下的管材挤压过程,并对模拟过程进行了实际挤压验证。结果表明:在变形温度900℃、应变速率0.1 s^-1条件下能成功挤压出?62 mm×12 mm的Ti-B25钛合金管坯,并且管坯具有良好的表面质量,组织中存在再结晶晶粒。管坯经过830℃/1 h+600℃/8 h固溶时效处理后具有良好的强-塑性匹配,满足舰船天线管使用要求。     

Nucleation sites for ultrafine ferrite produced by deformation of austenite during single-pass strip rolling

An austenitic Ni-30 wt pct Fe alloy, with a stacking-fault energy and deformation characteristics similar to those of austenitic low-carbon steel at elevated temperatures, has been used to examine the defect substructure within austenite deformed by single-pass strip rolling and to identify those features most likely to provide sites for intragranular nucleation of ultrafine ferrite in steels. Samples of this alloy and a 0.095 wt pct C-1.58Mn-0.22Si-0.27Mo steel have been hot rolled and cooled under similar conditions, and the resulting microstructures were compared using transmission electron microscopy (TEM), electron diffraction, and X-ray diffraction. Following a single rolling pass of ∼40 pct reduction of a 2mm strip at 800 °C, three microstructural zones were identified throughout its thickness. The surface zone (of 0.1 to 0.4 mm in depth) within the steel comprised a uniform microstructure of ultrafine ferrite, while the equivalent zone of a Ni-30Fe alloy contained a network of dislocation cells, with an average diameter of 0.5 to 1.0 μm. The scale and distribution and, thus, nucleation density of the ferrite grains formed in the steel were consistent with the formation of individual ferrite nuclei on cell boundaries within the austenite. In the transition zone, 0.3 to 0.5 mm below the surface of the steel strip, discrete polygonal ferrite grains were observed to form in parallel, and closely spaced “rafts” traversing individual grains of austenite. Based on observations of the equivalent zone of the rolled Ni-30Fe alloy, the ferrite distribution could be correlated with planar defects in the form of intragranular microshear bands formed within the deformed austenite during rolling. Within the central zone of the steel strip, a bainitic microstructure, typical of that observed after conventional hot rolling of this steel, was observed following air cooling. In this region of the rolled Ni-30Fe alloy, a network of microbands was observed, typical of material deformed under plane-strain conditions.     

Luders deformation of low-carbon steel

The development of Chernov–Luders bands on elastoplastic transition in low-carbon steel is investigated. The main factors responsible for the creation and development of the bands are identified. The kinetics of the mobile band boundaries (fronts) is of particular interest. The characteristic speeds are determined. The nucleation rate of Chernov–Luders bands exceeds their expansion rate by more than an order of magnitude. The simultaneous development of more than one band, with the appearance of several moving fronts, is considered. In all cases, the fronts of the Chernov–Luders bands move at matched speeds, so that, at any time, the generalized expansion rate of the deformation zone is constant. The influence of the strain rate on the kinetics of the band fronts is analyzed. Both the generalized expansion rate of the deformed zone and the speeds of individual fronts increase with increase in the loading rate. This is a nonlinear dependence (a power law). The fronts of the Chernov–Luders bands are complex in structure. Different sections of the front may move at nonuniform speeds, so that the front is locally distorted and split. Ahead of the front, in the undeformed sample, precursors whose configuration resembles that of the incipient Chernov–Luders bands may be observed. When they meet, the fronts of adjacent bands cancel out. Annihilation of the band fronts is a complex process, characterized by the formation of precursors and secondary diffuse Chernov–Luders bands. These findings indicate that the simplified concept of the Chernov–Luders bands as a deformed region in a loaded sample, as the front of a band, or as the boundary between deformed and undeformed zones must be revised. A microscopic theory of Luders deformation is based on the cascade growth in density of mobile dislocations on account of their breakaway from the points of attachment and their subsequent multiplication, which occurs instantaneously at the upper yield point within the crystallite (grain). At the same time, the formation of a mobile macroscopic strain front calls for the transfer of plastic deformation by adjacent grains, without strengthening. In other words, grain-boundary accommodation is required. The results obtained suggest that the Chernov–Luders band is such an accommodation zone, and so it has a complex structure.     

FeSiAlCr合金/W型六角晶系Ba铁氧体复合粉体的制备及微波特性

以雾化Fe85Si2Al6Cr7粉和溶胶凝胶法制备的W型六角晶系Ba1Co0.9Zn1.1Fe16O27铁氧体粉末为原料,通过高能球磨复合改性得到FeSiAlCr合金/W型六角晶系Ba铁氧体复合粉体。采用X射线衍射仪(XRD)和扫描电镜(SEM)对该粉体的微结构和形貌进行分析和观察,利用微波矢量网络分析仪系统测定粉体试样在2~18 GHz频段内的复介电常数和复磁导率以及吸波涂层试样板的吸波性能,研究该复合粉体的微波电磁特性和电磁损耗性能。结果表明,FeSiAlCr合金/W型六角晶系Ba铁氧体复合粉体颗粒保持W型铁氧体的六角片状晶粒形貌和微结构;其ε′、ε″、μ′和μ″均高于W型铁氧体而低于Fe合金的对应值;FeSiAlCr合金含量与复合材料的磁损耗和介电损耗的相对强弱密切相关,Fe合金含量适中的复合材料,其吸波涂层厚度为2 mm时,在2~18 GHz全频段的吸波性能高于20 dB,峰值点达50 dB。