Er、Nd对Mg-0.6Zr合金组织和性能的影响

采用金相显微镜、扫描电镜及能谱分析等手段,研究了Er、Nd对铸态Mg-0.6Zr合金的组织和常温力学性能的影响.结果表明,Er、Nd对Mg-Zr镁合金组织均有细晶强化和固溶强化作用,提高了合金的力学性能.Mg-0.6Zr合金中添加Nd、Er后晶粒尺寸由300 μm分别细化至80 μm和50 μm左右.添加0.94%的Nd后,Mg-0.6Zr合金的抗拉强度和伸长率分别提高了13.87%和137.1%,屈服强度基本不变.而添加1.09%的Er后,Mg-0.6Zr合金的抗拉强度、屈服强度和伸长率分别提高了11.16%、11.94%和2.35%.复合加入Er和Nd时,合金的抗拉强度同单独加入Er后合金的抗拉强度相当,屈服强度和伸长率略有下降.     

Al2O3f／Mg-9Al-0．5Nd复合材料的组织与压缩性能

采用无压浸渗技术制备了Al2O3f/Mg-9Al-0.5Nd复合材料,利用扫描镜、X射线衍射仪、电脑伺服材料试验机,研究了复合材料的微观组织变化、压缩性能和断口形貌.结果表明,复合材料组织中出现了Mg2Si新相和少量的粒状和杆状稀土相;热处理后Mg2Si有增多的趋势,尺寸略有增大;复合材料经过T4和T6处理后压缩强度有所下降,由铸态的346.5 MPa下降到250.5 MPa和327.5 MPa;经T6处理后,复合材料的压缩断裂方式由准解理断裂变为混合断裂,存在少量纤维从基体中拔出的现象.     

Nd:YAG激光焊接中装夹预紧力对焊缝的影响

由于在焊缝处热影响区会产生较小的力的作用,预夹持力的大小在焊接过程中会不断变化.热膨胀、冷却过程中的收缩以及工件宽度的微小减少都会通过焊点影响夹持力的变化.试样的拉伸试验结果表明,加裁在试样上的夹持力一般会提高焊缝的断裂力,更重要的是可以得到优化后的焊接夹持力.     

稀土Nd及热处理对Al2O3f/Mg-9Al复合材料组织和性能的影响

复合材料的硬度分别达到232HB、262HB.     

Chemical fingerprinting of whitewares from Nanwa site of the Chinese Erlitou state

Whitewares are among the most significant finds from Erlitou, China’s earliest state (c. 1900-1500 BC). They were primarily discovered in small numbers from elite tombs of a few sites, leading to the hypothesis that they were made at only a few places and then circulated as prestige items. Recent archaeological work indicates Nanwa may be a whiteware production site. To facilitate determining provenances, we compare the ICP-MS trace elements and TIMS Sr isotopes of Nanwa whitewares with those from Tang dynasty (618-907 AD) Gongxian kilns and Song dynasty (960-1279 AD) Ding kilns. Although all were made of white-firing kaolinic clays, each of the three groups shows a different chemical composition. Furthermore, samples from Nanwa are chemically consistent and restricted in a way analogous to those from Gongxian and Ding, implying that Nanwa whiteware was probably produced in situ. In addition, Gongxian and Ding samples define two separate linear arrays in their ⁸⁷Rb/⁸⁶Sr versus ⁸⁷Sr/⁸⁶Sr ratios, demonstrating that the clays for these samples are respectively related geochemically. Nanwa samples fall out of the linear arrays of both Gongxian and Ding, indicating that Nanwa whiteware clays were not derived from the same source rock as Gongxian clays, although the two sites are only some 25.5 km apart. In sum, beyond the general similarity of kaolinic clays used at Nanwa, Gongxian and Ding and the geographical proximity of those sites, finer distinctions of elemental and Sr isotopic contents indicate relatively unique chemical characteristics for each group. These traits provide valuable criteria to source traded ceramics of uncertain origins.     

Characteristics of Ions Emitted from Laser-Induced Silver Plasma

In this work, study of laser-induced ions is presented. The plasma was produced by focusing a Nd：YAG laser, with a wavelength of 1064 nm, a pulsed width of 9-14 ns, a power of 1.1 MW and energy of 10 mJ, on silver target in vacuum （10-3 Torr= 1.3332 Pa）. The characteristics of ion streams were investigated by CR-39 detectors located at angles of 0°, 30°, 60° and 90° with respect to normal of the target. The distance between the silver target and each detector was 11 cm. The energy of silver ions was found ranging from 1.5 eV to 1.06E4 eV. There was a high concentration of ions with low energy as compared to those with high energy, showing the energy distribution amongst the ions. The flux of ions was maximum in the axial direction which was decreasing with the angle increase with respect to normal of the target, and finally became minimum in the radial direction. Hence the silver ions have shown anisotropic behaviour.     

Laser beam machining—A review

Laser beam machining (LBM) is one of the most widely used thermal energy based non-contact type advance machining process which can be applied for almost whole range of materials. Laser beam is focussed for melting and vaporizing the unwanted material from the parent material. It is suitable for geometrically complex profile cutting and making miniature holes in sheetmetal. Among various type of lasers used for machining in industries, CO₂ and Nd:YAG lasers are most established. In recent years, researchers have explored a number of ways to improve the LBM process performance by analysing the different factors that affect the quality characteristics. The experimental and theoretical studies show that process performance can be improved considerably by proper selection of laser parameters, material parameters and operating parameters. This paper reviews the research work carried out so far in the area of LBM of different materials and shapes. It reports about the experimental and theoretical studies of LBM to improve the process performance. Several modelling and optimization techniques for the determination of optimum laser beam cutting condition have been critically examined. The last part of this paper discusses the LBM developments and outlines the trend for future research.     

Nd~(3+)玻璃激光器选模调Q技术的实验研究

目前国内外已有不少报道以YAG或YLF等晶体为工作介质进行预激光调Q选单纵模,并取得良好的效果,而用Nd~(3+)玻璃为工作介质进行这方面工作的报道尚属少见。众所周知,单纵模的获得是以单横模为前提的,为此我们在钕玻璃激光器上首先进行了选模(横模)调Q技术的实验,很容易就获得方向性极好的TEM_(00)模或某一低价横模的高功率激光输出,实现了     

磨削加工对圆柱钕铁硼永磁合金退磁曲线隆起度的影响

发现圆柱钕铁硼永磁合金经过磨削加工后，其内禀退磁曲线隆起度降低，从而也降低了磁能积。通过实验证明，隆起度降低是磨削加工应力所致，适宜的磨削工艺和热处理则可减少和消除其影响。     

Nd:YAP激光烧灼治疗涎腺囊肿

采用Nd:YAP激光烧灼治疗涎腺囊肿120例,有效率为100%,疗效优于其它疗法。