SiGe:GaP合金的微观结构和温差电特性

经高温热处理后的 SiGe∶GaP 半导体温差电材料,其微观结构由具有富 Si 相特征变化成为具有富 Ge 相特征,温差电优值也得到了提高。实验还表明,材料晶格热导率的降低与富 Si 相的消失和富 Ge相的出现有关。然而,塞贝克系数和电导率的显著变化却与微观结构中富 Si 相和富 Ge 相的变化基本无关。通过对材料微观结构和温差电特性比较发现,具有富 Ge 相特征的微观结构对应于较大的温差电优值。     

铝锂合金力学性能的各向异性

针对当前困扰铝锂合金实际应用的各向异性问题，概述关于铝锂合金中各向异性的表现规律，产生机理及对于降低各向异性所采用的方法等方面的研究现状和进展，对铝锂合金各向异性表现与微观组织结构的关系以及目前克服各向异性所采用方法的局限性进行分析。就此提出，若彻底解决这一问题则必须采用更先进的合金化方法及热加工工艺，研制新一代铝锂合金的观点和研究方向。     

An investigation of pore cracking in titanium welds

Two welded Ti-6A1-4V pressure vessels leaked prematurely in service. The leaks were caused by cracks emanating from weld porosity. The cracks originated during fabrication, with subsequent growth in service leading to the formation of the leak paths. Pore cracking is thought to be caused by a mechanism that involves both sustained-load and cyclic contributions, with the former being the more prominent. It is shown that the tendency for cracking is influenced by pore position and that pore size is not a deciding factor in that regard. The factors that govern pore cracking are discussed, and the possible role of interstitial embrittlement is assessed.     

Al的添加对Gd-Co合金的影响

用X射线衍射、扫描电镜和磁性测量等方法研究了Al的添加对Gd-Co合金的影响。研究结果表明：在一定范围内掺杂Al导致GdCo2、GdCo5和Gd2Co17晶格常数增大，但仍保持各自的晶体结构；Al的添加使GdCo2和Gd2Co17的居里温度降低，但是对于GdCo2却是先增后减。该结论为寻找新的磁性材料提供了有价值的参考。     

Rapid determination of the fracture toughness of metallic materials using circumferentially notched bars

Three types of material whose fracture toughness tests were previously performed by using circumferentially notched bars, namely (1) a dual-phase steel with three different morphologies; (2) an Al-Zn-Mg-Cu-wrought alloy; and (3) Al-Si-cast alloys with three different Si contents, were investigated in terms of accuracy and reliability of the testing method. Also, the advantages of using circumferentially notched bars for fracture toughness determination of metallic materials were discussed. With the help of stress concentration factors, which are associated with the bluntness of the notch, correction factors for the fracture toughness calculations are derived. The corrected fracture toughness values are found to be close to the uncorrected ones, implying that the testing procedure is reliable.     

Oscillating Cup Viscosity Measurements of Aluminum Alloys: A201, A319 and A356

An oscillating cup viscometer was developed to measure the absolute viscosities of molten metals. Previous experiments established the capability of the apparatus to characterize the viscosities of molten nickel-based superalloys. However, modifications to the instrument and its theoretical analysis were required for reliable measurements on molten aluminum alloys, presumably due to their lower densities and lower viscosities. The theoretical literature for the fluid flow inside an oscillating cup is reviewed, and a working equation without any correction factor is developed for the improved viscometer. Some design parameters of the viscometer that directly affect the accuracy of viscosity estimation by using the working equation are discussed. A special vertical furnace was adopted to uniformly heat a longer cylindrical sample (10 mm inner diameter and 120 mm length) with a temperature difference of less than 2°C over the sample length. The measuring procedure was also improved to get more accurate motion parameters. It is estimated that the working equation and improved instrument provide an uncertainty of less than 4%. In addition, applications and experimental data are presented for pure aluminum and three aluminum alloys: A201, A319, and A356.     

Electroplating of nickel-cadmium alloys from alkaline solutions

The electroplating of Ni-Cd alloy coatings was carried out from alkaline baths (pH 10). For comparison, electroplating of the parent metals, Ni and Cd, was performed individually under the same conditions. The cathodic current efficiency for codeposition was high and decreased with increasing current density. The codeposition process is an anomalous type of plating with Cd being the preferentially deposited metal. The Ni content in the deposits increased with increasing current density. This increase in Ni content improves the corrosion resistance and microhardness of the deposits. X-ray diffraction analysis showed that the deposits consist of a mixture of Ni, β, γ, γ¹ phases.     

形状记忆合金薄膜的研究与发展

形状记忆合金是智能结构研究中重点开发的传感和驱元件材料之一。然而ＳＭＡ体材料响应速度较慢，在一五程度上限制了它的应用。ＳＭＡ薄膜弥补了这一缺陷，且更易于智能能结构集成化。本文介绍了国内外关于ＳＭＡ薄膜研究的现状。并展望了未来发展。     

施加复合电磁搅拌对A357合金微观组织的影响

在半固态加工技术中，电磁搅拌是最早应用于制备非枝晶浆料的方法之一，同时也是半固态触变压铸技术最早获得工业应用的重要技术基础之一。采用自行开发的电磁搅拌器，研究了多种不同电磁搅拌方式在不同工艺条件下，单独施加或复合施加对A357合金微观组织的影响。试验结果表明：单一施加旋转感应电磁搅拌时，浆料径向组织很不均匀；单一施加无芯感应电磁搅拌。当搅拌电流较小时，径向组织也不均匀，增大电流，浆料质量有明显改善；采用（旋转感应＋无芯感应）复合电磁场进行复合电磁搅拌时，可在电流较小时获得满意的浆料质量。     

Crack growth in aluminium alloy sheet material under flight-simulation loading

Crack propagation tests were carried out on 2024-T3 sheet specimens to study the effects of omitting low-amplitude cycles from the gust-dominated TWIST load sequence (MiniTWIST) and the removal of small load ranges from the manoeuvre-dominated FALSTAFF load sequence (short FALSTAFF). In other tests high-amplitude loads of TWIST and MiniTWIST were truncated at different levels. The results are compared with data from similar test programmes, including crack initiation. Attention is paid to unstationary crack growth retardation and a transient retardation during initial crack growth started by an artificial crack.