铍铜替代用高性能铜基弹性合金的开发现状

高性能铜基弹性合金的开发是国内外铍铜行业普遍关注的焦点。本文概述了铍铜替代用高性能铜基弹性合金如Cu-Ti系、Cu-Ni-Sn系、Cu-Ni-Cr系、Cu-Ni-Mn系、Cu-Ni-Al系合金等的开发现状。指出了国内外在铍铜替代用高性能铜基弹性合金领域的研发及应用水平差距。     

Study on the microstructure and mechanical properties of Nd:YAG pulsed laser beam weld of UNS-C17200 copper beryllium alloy

In this study, the microstructure of Nd:YAG pulsed laser welding of copper beryllium sheet has been investigated by tensile and hardness tests, optical and scanning electron microscopy (SEM) and X-ray diffraction (XRD). The SEM images reveals three distinct solidified structures due to various thermal gradients occurred in the fusion zone. The XRD patterns show that the preferred solidification directions are like other FCC materials. Tensile strength of the weld metal is lower than that of the base metal since the CuBe phase precipitates during solidification. The effects of pulsed laser parameters on the weld pool dimensions were also studied. The results show that by applying constant pulse energy, focused beam diameter should be kept as low as possible to obtain the weld pool with the highest penetration and the least width. Moreover, the effect of passive layer on the reflectivity of surface by incident beam was investigated. It was found that weld pool increases when the laser energy is high due to multiple internal reflections.     

铍的生产现状与应用开发

介绍了世界铍矿资源和储量的分布情况及主要厂家的生产现状。详细地叙述了金属铍、铍铜、铍合金和氧化铍的应用与开发。分析和预测了2000年铍的市场供需情况。     

国外空间光学扫描机构现状

空间光学扫描机构是光机扫描型相机的关键部件之一,其性能直接影响到相机的成像质量。本文对高性能光学扫描机构的基础关键技术进行了阐述,并对国外先进光学扫描机构进行了调研。根据扫描维数各选取了三种典型的扫描机构,对它们的性能指标和整体方案进行了介绍,对提高我国相关扫描机构的技术水平具有借鉴意义。     

QBe1.9和Cu-0.5Cr-0.2Zr合金显微组织及焊接性能分析

系统研究QBe1.9铍青铜和Cu-0.5Cr-0.2Zr铬锆铜热处理前后及TIG焊后的力学性能、导电性、显微组织。结果表明,经固溶时效处理后,QBe1.9合金析出具有体心立方的硬质γ相,抗拉强度由560.57 MPa提高到761.95 MPa,硬度由246 HV0.02提高到362 HV0.02,电导率由27.43%IACS提高到50.19%IACS。铬锆铜析出具有体心立方的Cr原子及锆的金属间化合物,抗拉强度由290.01 MPa提高到411.17 MPa,硬度由81 HV0.02提高到116 HV0.02,电导率由32.75%IACS提高到58.31%IACS。两种铜合金热处理后分别进行TIG焊,焊缝硬度及焊接接头强度均较母材低,热影响区在距焊缝中心1 mm左右,均在焊缝处断裂,为准解理断裂。     

Cross Section Measurement for 199Hg(n,n′)199m Hg Reaction from 0.78 to 6.3 MeV

Cross sections for the ¹⁹⁹Hg(n, n′)^199m Hg reaction have been measured at 10 energy points from 0.78 to 6.3 MeV by the activation method. Monoenergetic neutrons below 2 MeV were produced by the ⁷Li (p, n)⁷Be reaction and those above 2 MeV were produced by the D(d, n)³He reaction using a 5.5 MV Van de Graaff accelerator. The neutron flux was determined with a proton recoil telescope counter and In-foils. The measured cross sections were expressed by an empirical formula. The fission spectrum averaged cross section calculated with this formula is 238.3 mb for the Watt-type fission spectrum, and is about 14% smaller than that recently measured by three of the authors.     

Extractive Metallurgy of Beryllium

A comprehensive review of the extractive metallurgy of beryllium is presented. Due to the strategic importance and element of secrecy surrounding the metal, any open literature on beryllium is rather limited. However, this review has been made to cover all important aspects of beryllium extraction technology namely, resources of the metal; processing of ores; reduction of fluoride and oxide to get metal and alloy; refining of the metal; post preparation processes to shape metal through powder metallurgical route and preparation of foils and ceramics. Special attention has been given to the topic of toxicology and pollution control. Recycling of beryllium will form the concluding section. Information on the removal of impurities during the preparation of intermediate products as well as during reduction to metal and its alloys are described with process principles. Thus this review, with the help of discussion on each unit process and at the same time emphasising on the problems faced in large scale handling of this toxic metal and its compounds, shall provide substantial information presently available on the extractive metallurgy of beryllium.     

铍对Al-34%Mg共晶合金高温氧化行为的影响

为提高铝镁合金的高温抗氧化性能,以合金化的方式在Al-34%Mg共晶合金中添加不同含量的铍元素,将所得合金分别于空气中在420℃进行准连续恒温氧化试验和从470℃到室温循环氧化试验,对其氧化行为进行了研究.结果表明:加入微量(≥0.01%)铍能提高共晶合金在固、液态时的高温抗氧化能力,并能改善氧化层的粘附性与自愈能力;含有BeO的氧化膜大大降低了合金表面氧化物的生长速度.     

金属铍材室温平面应变断裂韧性测试方法

介绍了金属铍材的室温断裂韧性测试方法,并对不同方法进行了讨论,认为采用载荷比（Pmin/Pmax)为－3的拉－压疲劳循环加载方式,可以制备出脆性金属铍材KIC测试所需要的疲劳裂纹,所测试的铍材室温断裂韧性KIC均值为9．91MPa.m^1/2,标准偏差为0．73MPa.m^1/2,符合国家标准要求。     

Mg—9Al—0.5Zn—9.1Be—XCa合金的组织和力学性能研究

研究了Be和Ca元素对Mg-9Al-0.5Zn合金显微组织和力学性能的影响。结果表明：在Mg-9Al-0.5Zn镁合金中添加0.1Be导致合金组织粗化和力学性能下降,同时在晶粒内部形成粒状γ相（Mg17Al12）。在此基础上添加Ca可以使合金组织细化,且含量越高,细化效果越明显。Mg-9Al-0.5Zn-0.1Be-0.5Ca合金具有较高的综合力学性能,但是进一步增加Ca含量导致合金常温力学性能下降。由于Al2Ca相良好的高温强化作用,因此当Ca含量小于1％时,Mg-9Al-0.5Zn-0.1Be-XCa合金具有较高的高温强度,进一步增加Ca含量会增大合金脆性。