国际标准化组织ISO结对协议简介和实践

本文介绍了国际标准化组织ISO结对协议的概念、类型、基本要求和原则,以及达成结对协议的具体步骤。介绍了ISO/TC67/SC2石油、石化和天然气工业设备材料和海上结构技术委员会管道输送系统分委员会并行秘书处运作三年来的一些实践经验和体会。     

Ni75Al7.5V17.5合金时效沉淀D022相的孪生相场模拟

为揭示合金固态相变初期新相形成机制,尤其是D022相变孪晶形成机制,利用三元微观相场模型对Ni75Al7.5V17.5合金于1 273 K下等温时效沉淀过程的前3个阶段进行了模拟.计算结果表明,L12结构的Ni3Al有序相首先沿惯析面(100)从母相中共格形核,而后D022结构的Ni3V有序相在先析出的L12相和母相的相界形核.由于{100}的反相畴界上形成较大的共格失配,导致能量较高且不稳定,反相畴界在两相生长中遭到破坏,而晶面{110}的界面能比{100}的反相畴界能低,生长过程中D022的3种变体互相正交排列形成阶梯状结构的{110}孪晶面.     

连续退火对5% Mn超细晶TRIP钢组织性能的影响

为开发强度和塑性良好配合的第三代汽车钢,采用CCT-AY-Ⅱ型钢板连续退火机模拟分析了不同退火温度和时间对0.1C-5Mn中锰TRIP钢组织性能的影响规律.采用SEM和EBSD等微观分析方法观察不同工艺下制备的中锰TRIP的微观组织,利用XRD方法测量残余奥氏体体积分数,通过实验测量其力学性能.结果表明:实验的中锰TRIP钢在650℃保温3 min退火后获得最佳的综合力学性能,其抗拉强度为1 022 MPa,总延伸率为19.3%,强塑积为20 GPa·%;应变前期试验钢中大量残余奥氏体发生转变,超细晶间的协调机制对试验钢的塑性起主导作用.     

预变形及退火处理提高AZ31镁合金的塑性

研究了预变形及退火处理对挤压态AZ31镁合金压缩力学性能的影响,结果表明:沿挤压方向进行应变量为0.086的预压缩变形,随后在300℃下进行0.5小时退火处理,可显著提高镁合金的塑性,其压缩率比一次压缩至破碎的压缩率提高约137%。织构及金相分析结果表明:预变形使(0002)基面发生了近90°的转动,由平行挤压方向变为与挤压方向垂直,且产生了大量孪晶组织。退火处理不改变(0002)基面织构,但消除了孪晶且出现了细小再结晶晶粒,因而提高了镁合金的塑性。     

Growth of (111) HgCdTe on (100) Si by MOVPE using metalorganic tellurium adsorption and annealing

(lll)B CdTe layers free of antiphase domains and twins were directly grown on (100) Si 4°-misoriented toward<011> substrates, using a metalorganic tellurium (Te) adsorption and annealing technique. Direct growth of (lll)B CdTe on (100) Si has three major problems: the etching of Si by Te, antiphase domains, and twinning. Te adsorption at low temperature avoids the etching effect and annealing at a high temperature grows single domain CdTe layers. Te atoms on the Si surface are arranged in two stable positions, depending on annealing temperatures. We evaluated the characteristics of (lll)B CdTe and (lll)B HgCdTe layers. The full width at half maximum (FWHM) of the x-ray double crystal rocking curve (DCRC) showed 146 arc sec at the 8 |im thick CdTe layers. In Hg_1−xCd_xJe (x = 0.22 to 0.24) layers, the FWHMs of the DCRCs were 127 arc sec for a 7 (im thick layer and 119 arc sec for a 17 (im thick layer. The etch pit densities of the HgCdTe were 2.3 x 106 cm2 at 7 ^m and 1.5 x 106 cm-2 at 17 um.     

Creep mechanism of Mg-Nd-Zn-Zr alloy at ambient temperature

Magnesium alloy＇s creep stress exponent and creep mechanism at the room temperature were analyzed by TEM. Relationship among strain, stress and creep time was studied. The creep rate of some mechanisms were calculated. The results show that the dislocation mechanism is possible. The deformation mechanism is dislocation slipping on basal plane, and twinning improves creep deformation.     

Deformation behavior ofAZ31 magnesium alloy at different strain rates and temperatures

The deformation behavior of AZ31 was examined by compression and tension testes over a wide strain rate and temperature range, strain rate from 10^-3 to 10^3 s^-1, temperature from 300 to 623 K. Analysis of flow behavior and microstructural observations indicate that in tension tests dislocation glide is the most important deformation mechanism in the test strain rate and temperature range, while in compression tests twinning deformation mechanism is important at lower temperature when the strain rate ranges from 10^-3 to 10 s^-1. At 10^3 s^-1 strain rate, dislocation glide and twinning are present at the same time. At the strain rate of 2 964 s^-1, adiabatic shear band can be found easily, even at the strain rate of 1 537 s^-1 adiabatic shear localization zone can be found. In adiabatic shear localization zone, there are fine recrystallization grains. But in adiabatic shear band, the grains cannot be identified by optical microscopy.     

Alpha-quartz 3. Origin of cellular structure of synthetic quartz

Surfaces of optically flawless and untwinned quartz single crystals, both natural and synthetic, were dissolved both at room temperature and at high temperatures in autoclaves using appropriate etchants. The features that develop have been optically studied, and x-ray transmission projection topographs of some of the specimens from the same natural quartz were also taken and studied. A model has been proposed to explain the anomalies detected earlier by other workers regarding the nature of line defects found in as-grown synthetic quartz, and the absence of lateral strain in the polygonised microcracked layer of the specimens of the present series of experiments.     

大晶粒纯镁疲劳变形过程中交叉滑移迹线的分析

在室温条件下研究了大晶粒纯镁疲劳变形过程中有可能激活的滑移系统及滑移迹线。结果表明,经过疲劳变形后大量的纵横交叉滑移迹线在样品表面产生,基于晶粒取向与滑移迹线方向的综合判定,这种纵横交叉滑移迹线是由反复疲劳变形过程中基体的基面滑移与同一区域内｛102｝孪生过程中所再次产生的基面滑移而形成。通过实验观察到最有可能发生的锥面滑移系统为在｛101｝面上所产生的<113>锥面滑移,但总体上来说,基面的滑移迹线比锥面的滑移迹线更密集,这说明锥面滑移在整个疲劳变形过程中被抑制。     

Exploring the Formation Mechanism of Deformation Twins in CrMnFeCoNi High Entropy Alloy

The deformation twins initiated in CrMnFeCoNi high entropy alloy at cryogenic temperature are experimentally studied. Under the external loading, a three-dimensional shear stress concentration originating from dislocation tangling at both the grain boundaries and twin boundaries could be formed, which promotes emission of partial dislocations from the planar defects and is thus considered to be the key factor for twin formation. A sympathetic nucleation mechanism is proposed to describe the nucleation behaviors of twins.