Effect of microstructural parameters on the properties of W-Ni-Fe alloys

The aim of this research was to examine the effect of microstructural parameters on the tensile properties of dif- ferent compositions of tungsten heavy alloys. The microstructural parameters (grain size, connectivity, contiguity, and solid volume fraction) were measured and were found to have a significant effect on the tensile properties of tungsten-based heavy alloys. The microstructural parameters of W-Ni-Fe alloys are sufficiently different to present a range of me- chanical properties. It is concluded that the mechanical properties of tungsten heavy alloys largely depend on the micro- structural parameters and their ductility is particularly harmed when grains are contiguous.     

加温拉伸条件TiCp—AlNp／Al复合材料组织与力学性能

主要研究了加温拉伸下TiCp—AlNp/Al复合材料组织与力学性能,具体探讨了温度对此复合材料屈服强度的影响,并结合不同温度拉伸断口的形貌来讨论复合材料的断裂机制;基于实验数据和电镜观察,讨论了复合材料塑性与拉伸温度的关系,分析了自生相颗粒TiC和AIN在加温拉伸的过程中强化基体的微观机制。     

硅对GD钢下贝氏体组织形态及力学性能的影响

本文研究了不同硅含量的高强韧低合金冷模具钢(代号GD钢)经马氏体—下贝氏体复相处理后下贝氏体的组织形态、亚结构和数量,讨论了GD钢的成分、组织和性能之间的关系。结果表明,GD钢的硅含量对下贝氏体的相变过程和显微结构起决定性的作用。当GD钢的硅含量达到1.82％时,复相组织中下贝氏体呈准下贝氏体形态,且复相组织表现出最佳的强韧性配合。     

Role of some rare earth (RE) ions (RE = La, Pr, Nd, Sm, Gd and Dy) in crystal and mechanical behaviours of sol-gel derived ZrO2-2 mol% REO2O3 spun fibres calcined at 1300°C

Crystal behaviours such as crystallization temperature (amorphous to tetragonal (t) zirconia), tendency of phase transformation (tetragonal to monoclinic (m) zirconia) and lattice strain were studied with mechanical property e.g. tensile strength of sol-gel derived ZrO₂-2 mol% RE₂O₃ (RE = La, Pr, Nd, Sm, Gd and Dy) spun fibres. Rare earth cations of varying sizes played a significant role in changing the above mentioned properties of ZrO₂-2 mol% RE₂O₃ fibres. It was found that with decreasing the ionic size difference between the zirconium and RE ions, crystallization temperature (amorphous →)t-ZrO₂) decreased, the probability of phase transformation (t→m) decreased, lattice strain which is related to lattice distortion decreased and tensile strength increased.     

Proteins in white wine, I: Procyanidin occurrence in soluble proteins and insoluble protein hazes and its relationship to protein instability

The presence of procyanidins in wine protein fractions was established by a chemical assay and by pyrolysis DI-EI MS/MS of proteins. The chemical assay, involving acid-catalysed oxidative degradation of the procyanidins, gave cyanidin which was specifically quantified by HPLC. The assay was calibrated with purified grape seed tannin (GST); procyanidin was expressed in μg GST. Cyanidin yields were little altered by the presence of a large excess of protein. The limit of detection of the assay was 1 μg GST and the limit of quantification 3.5 μg GST. Both heat-induced and natural hazes isolated from various white wines were all shown to contain procyanidins, with a content ranging from < 0.02 to 4.9% (w/w). Although a crude soluble protein isolate from white wine contained a detectable amount of procyanidins, none were found in fractions separated chromatographically from this isolate. This observation, and the absence of procyanidins in resolubilised heat-induced haze, demonstrated that procyanidins are only weakly associated with both heat-induced hazes and soluble wine proteins. Nevertheless, procyanidins appear to be implicated in the formation of protein hazes in wine, because many soluble wine proteins that had been rendered free of procyanidins would precipitate to give haze in wine but not in model wine which was devoid of phenolic compounds.     

取心工具螺纹机械性能的改进

针对现有各型取心工具因螺纹结构特点的局限，存在抗拉、抗扭强度不高的问题，在工具多次使用后易出现疲劳损伤、螺纹胀裂等现象，四川石油取心中心对现有取心工具进行了改进，并计算对比了改进前后2种螺纹的抗拉和抗扭强度，结果证明改进后的取心工具的螺纹机械性能被大大提高。     

Sensitization Behaviour of Manganese‐Alloyed Austenitic Stainless Steels

Manganese is an essential alloying element in advanced austenitic stainless steels with specific properties such as high resistance to harsh corrosive environments, high strength or low material costs. These materials are often used for welded constructions which have to be highly corrosion resistant. Hence it has to be ensured that the heat input during welding does not initiate the precipitation of chromium carbide resulting in a susceptibility to intergranular corrosion. This leads to the question whether the sensitization behaviour of manganese‐alloyed austenitic stainless steels is comparable to that of the well‐known conventional chromium nickel austenites. In the present work the effect of heat‐input on the susceptibility of the CrNi‐steel 1.4301 and the CrNiMn‐steel 1.4376 to intergranular corrosion (IGC) was considered. Investigations were carried out by corrosion testing in the so‐called Strauss‐Test to elucidate the effect of the annealing temperatures on the microstructure. Furthermore, the influence of heat treatment on the mechanical properties was evaluated by tensile testing. As a result, it could be demonstrated that manganese‐alloyed austenitic stainless steels like grade 1.4376 exhibit a sensitization behaviour very similar to the conventional austenitic steel grades. The same kinds of tests on intergranular corrosion resistance can be applied for both types of materials.     

A statistical theory of the tensile strength of short-fiber-reinforced composites

This paper is concerned with the prediction of the tensile strength of short-fiber-reinforced composites by following the statistical theory of the strength of fiber bundles. Unidirectional, misaligned, and random-fiber directions are all treated. Depending on the fiber length, two failure modes can be distinguished. When the fiber length is smaller than 2L_c, where L_c is the critical transfer length, the composite should fail by direct fiber pull-out. By contrast, it the fiber length is longer than 2L_c, most fibers break first and are then pulled out. At small fiber lengths, the prediction of the present theory is one-half the value predicted by the conventional model. However, the prediction of the present theory is in close agreement with that of the conventional approach if the fiber length is long.     

TiAl（FL）冲击拉伸力学性能的试验研究

对全片层状组织的ＴｉＡｌ金属间化合物进行了三个应变率（１００ｌ／ｓ，３００ｌ／ｓ，８００ｌ／ｓ）的冲击拉伸试验研究，得到了材料在不同应变率下的完整的应力应变曲线。结果表明在不同应变率下，ＴｉＡｌ金属间化合物均为脆性破坏，但随着应变率的增加，材料的破坏 力和失稳应变也随之增大，具有应变率强化和动态韧性的变形特征，ＳＥＭ分析表明材料的破坏主要以穿晶破坏为主，并且随着层片位向的不同，断口的形貌也有很大差