热压/热变形Nd2Fe14B/α-Fe纳米双相永磁体的研究

为了制备各向异性块状Nd2Fe14B／α—Fe纳米双相永磁体，研究了热压／热变形工艺参数与样品微观组织结构、磁性能之间的关系。结果表明，饱和磁化强度Js随模压温度的升高而提高；而剩磁Jr、内禀矫顽力Hcj和最大磁能积(BH)max开始都随模压温度的升高而上升，但超过一定温度后反而降低；同时提高热压压力会使磁性能增加，而热变形温度对磁性能影响很小。热变形后样品垂直于压力方向的磁性能略高于平行于压力方向，呈现出轻微的各向异性。Nd2Fe14B／α—Fe纳米双相永磁材料在热压／热变形后没有产生晶粒的择优长大，在晶体学上仍然是各向同性的。     

Hydrogen Absorption and Release Behavior in Hydrogen Decrepitation Process of Nd-Fe-B Alloys

The behavior of hydrogen absorption and release in hydrogen decrepitation (HD) process of Nd-Fe-B alloys were investigated. The results reveal that the reactivity and the amount of hydrogen absorption in HD process are related to the surface activity of the alloy so that the fresh and active surface has a higher efficiency. The presence of Nd-rich phase at the grain boundary is an essential factor of the HD activity of the alloy at room temperature. On degassing, hydrogen is released from the HD powder continuously with increasing temperature. And the residual hydrogen is as low as 0.0015% at 1073K, which shows that the hydrogen is almost exhaused. It is feasible to remove the hydrogen from the HD powder by heating treatment at the temperature of 523-723K for 1h prior to the magnetic field forming in order to decrease the harmful effect of hydrogen on the easy axis alignment of HD magnet.     

桥口南--徐集地区三维地震资料连片处理技术

针对东濮桥口南—徐集地区三维地震资料的特点及本区块的地质要求，制定处理流程，应用能量均衡、面元均化、三维道内插、三维DMO叠加及三维一步法偏移等技术方法，研究解决因为不同年代、不同方法、不同参数所采集的地震数据在连片处理时存在的问题，精细处理三维连片资料，满足构造解释精度的要求，对进一步落实该区构造和增储上产具有重要的作用。     

Texture of Nanocomposite Nd2Fe14B/α-Fe Melt Spun Ribbons

Highly textured nanocomposite Nd9Fe84.5Nb0.5B6 ribbons were obtained by rapid solidification at wheel speeds from 15 to 20 m·s-1.X-ray diffraction(XRD)shows that these ribbons are preferentially orientated with the c axis of Nd2Fe14B phase perpendicular to the surface of the ribbons.The texture of Nd2Fe14B phase on the free surface is stronger than that on the contact surface and decreases with increase of wheel speed.The texture of Nd2Fe14B phase seems to be caused by the preferential growth of the crystal nuclei favorable orientation with their c-axes along the temperature gradient during rapid solidification,which can be explained by a growth circular cone(GCC).The intensity of the anisotropy can be expressed by the magnitude of the cone generating angle.The supercooling velocity and wheel speed will influence the cone generating angle,which in turn influences the anisotropy.The remanence and maximum energy product in the direction perpendicular to the ribbon surface is much higher than that in the direction parallel with the ribbon surface.High remanence and maximum energy product can be obtained in the direction perpendicular to the ribbon surface.The texture of Nd2Fe14B phase decreases gradually after annealing above 600 ℃,which is mainly attributed to the precipitation of new α-Fe from Nd2Fe14B phase with super-saturated Fe.Decreasing the annealing temperature or reducing the annealing time is beneficial for preserving the anisotropy of Nd2Fe14B phase after annealing.     

Effect of Multiple Alloying Elements on Microstructure and Magnetic Properties of Nanocomposite Nd2Fe14B／α-Fe Magnets

TheappearanceofnanocompositemagnetsbroketheremanencelimitpredictedbyStoner Wolhfarthmodethattheremanenceofisotropicmagnetwouldnotexceedhalfofitssaturationmagnetization[1] .Accord ingtoSkomski′scalculation[2 ] ,highmaximalenergyproduct (BH) maxof 80 0kJ·m-3 couldbeachievedinNd2 Fe14 B α FenanocompositewhentheaveragegrainsizeofNd2 Fe14 Bisrefinedtoabout 2 0nmandthatofα Fetoabout 10nm ,becauseoftheeffectofrema nenceenhancement (Mr Ms >0 .5 ) .Unfortunately ,thereported (BH) max(185kJ·…     

Effect of HD Process on Microstructure and Hard Magnetic Properties of NdFeAlB Magnet

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距离迁移成像算法在超宽带SAR成像中的应用

超宽带SAR是一种新体制雷达，在成像处理方面有特殊要求。本文详细介绍了距离迁移算法，对其每一个处理流程进行了详尽的分析，并进行了计算机仿真，最后利用超宽带SAR数据实际检验了算法的有效性。     

新型空冷贝氏体渗碳钢的研究

为了减少齿轮渗碳淬火后的变形和开裂 ,研制了一种新型空冷贝氏体钢 ,其成分为 (质量分数 ,% ) :0 2C ,0 7Si,一定量的Cr、Mn ,测定了其CCT曲线。用空冷贝氏体渗碳钢制作的齿轮 ,经渗碳后空冷 ,齿表面硬度在 6 1HRC以上 ,齿心部硬度在40HRC左右 ,冲击韧度为 82J·cm 2 ,较好地满足了齿轮的硬度和强韧性要求。齿尖渗碳层的显微组织是下贝氏体 高碳马氏体 ,齿的心部是贝氏体 低碳马氏体复相组织。这种组织保证了齿轮既具有较高的抗接触疲劳性能又具有较好的抗冲击能力。用该钢制造的齿轮变形小 ,精密度高 ,可极大地降低运行时的噪音     

合金元素对Nd2Fe14B/α-Fe磁性能的影响

通过单一添加 ,研究了C ,Pr,Nb对Nd2 Fe1 4B/α Fe纳米复合永磁体磁性能的影响 ;用少量C取代B ,可以显著提高Nd9Fe85.5Nb1 .0B4 .5-yCy 永磁体的内禀矫顽力iHc,用Pr代替部分Nd可以提高双相快淬薄带的矫顽力并改善退磁曲线的矩形度。当Nb含量控制为 0 .5 %时 ,Nd2 Fe1 4B/α Fe的各项磁性能均有显著提高。采用五因子二水平正交分析方法 ,研究了Ga ,Nb ,Zr,Hf和Pr复合添加对磁性能的作用。Nb是影响剩余磁极化强度Jr 和最大磁能积 (BH) max最为显著的因子 ,而Pr对iHc 的影响最强烈。另外 ,在Nb ,Pr之间 ,Nb ,Hf之间 ,Ga与Pr以及Ga与Hf之间的交互作用也对磁性能有显著影响 ,优化的合金成分为Nd2 .2 5Pr6 .75Fe84 .5Ga1 .5Nb0 .5B4 .5,在 15m·s- 1 带速下获得的最佳磁性能为Jr=1.0 5 3T ,iHc=5 3 0 .9kA·m- 1 ,(BH) max=12 4kJ·m- 3。     

铸锭组织及快淬工艺对R-Fe-B/α-Fe纳米双相永磁性能的影响

研究了名义成分为(Nd1-xPrx)9Fe84.85NbyCuzB5.5的R-Fe-B/α-Fe纳米双相永磁材料.利用扫描电镜和X射线衍射等手段研究了铸锭和快淬带的组织形态和相组成,并分析了铸锭组织和快淬工艺对快淬带和粘结磁体磁性能的影响.结果表明,无论是13kg铸锭还是50g铸锭,都是由基体(Nd(Pr))2Fe14B相,树枝状或颗粒状的α-Fe相,以及少量富Nd(Pr)相组成,只是小铸锭由于冷速快,组织比较细小.分别将13kg铸锭的柱状晶和中心等轴晶以及小铸锭以相同工艺制备成粘结磁体后发现,大铸锭制备的磁体性能略高于小铸锭,同时大铸锭不同部位制备的磁体性能相差约为10%.对于此成分合金,21m/s的快淬速度与700℃×10min的退火工艺是一个较好组合,制备的粘结磁体的最大磁能积为61kJ/m3.