材料期刊网

APPLICATION OF CtPARAMETER FOR CREEPFATIGUE CRACKGROWTH WITH SLOW LOAD RISING CONDITION

Author J.H. Lee 1) , K.B. Yoon2) , Y.J. Kim3)and U.B. Baek4) 1) Engineering Research Department , Korea Institute of Nuclear Safety , P.O. Box 114 , Yoosung , Taejon 305600 , Korea2) Department of Mechanical Engineering , Chung Ang University , 221 Huksuk , Dongjak , Seoul 156756 , Korea3) Department of Mechanical Engineering , Sungkyunkwan University , 300 Chunchun , Jangan , Suwon 440746 , Korea4) Failure Prevention Research Center , Korea Research Institute of Standards and Science , P.O. Box 102 , Yoosung , Taejon 305600 , KoreaManuscript received 18 October 1998

金属学报(英文版)

Most of the assessment equations for Ct which is a wellknown fracture parameter characterizing high temperature crack growth rates, have limited applicability to constant load conditions after sudden loading. However, crack growth due to creep can also occur under load varying conditions when load rising time is so long that accumulated creep deformation near the crack tip is not negligible.In this paper, the estimation equation of the Ctparameter which can be applied to the case of slow load rising, i.e., (Ct)r, is explained. And the correlation between (Ct)r at the end of the load increasing period and Ct at the beginning of the succeeding load hold period is discussed. Finite element analyses of several cases with various loading conditions were performed and results were presented to show the effectiveness of the proposed Ct estimation scheme. The general applicability of the equation is also discussed.

关键词: creep , null , null , null , null , null

Shear response of the Sigma 9 < 110 > {221} symmetric tilt grain boundary in fcc metals studied by atomistic simulation methods

Physical Review B

The shear response of the Sigma 9 < 110 > {221} symmetric tilt grain boundary (GB) in three fcc metals Cu, Al, and Ni has been studied by atomistic simulation methods with the embedded atom method for interatomic potentials and with a bicrystal model. By applying an energy minimization procedure, it was found that there are two optimized structures of this particular GB at zero temperature for all the three metals studied. Shear of bicrystals at room temperature has been studied by the molecular-dynamics simulation method. Various kinds of structure evolution behavior have been found for this GB depending on the shear direction: (1) pure GB sliding; (2) GB atomic shuffling accompanied by lattice dislocation emission from the GB; and (3) GB migration coupled with GB sliding, namely, GB coupling motion. The GB coupling motions can differ in the direction and distance of the GB migration depending on the shear direction. An analysis with the aid of the coincidence site lattice theory indicates that the structure evolution behavior can be attributed to several elementary structure transformations inherent to this particular GB. A pair parameter (lambda, kappa) is proposed to describe the GB coupling motions.

关键词: sliding resistance;molecular-dynamics;cubic-crystals;misorientation;dependence;dislocations;copper;nanocrystalline;deformation;aluminum;stress

The effect of crystallographic orientation on the oxidation behavior of a single-crystal nickel-base superalloy

Oxidation of Metals

The oxidation kinetics of DD100 nickel- base single- crystal alloy, with ( 221) and ( 100) surface orientations were tested in this study by thermogravimetry. A pronounced anisotropy in both the cyclic and isothermal oxidation resistance of DD100 alloy was observed. The ( 221) crystallographic surface of DD100 had a slower oxidation rate than the ( 100) surface when isothermally exposed to stationary air at 950degreesC, whereas the opposite results were obtained at 1050degreesC. When cyclically oxidized at 1100degreesC, the weight loss of samples with ( 221) surfaces was significantly greater than that of ( 100) surfaces, so that the cyclic- oxidation anisotropy was more remarkable at 1100degreesC than at 950degreesC. The different spatial alignment of the gamma' / gamma interface is thought to be responsible for the anisotropic oxidation behavior of the nickel- base single crystal alloy.

关键词: single-crystal nickel-base superalloy;high-temperature oxidation;oxidation kinetics;oxidation anisotropy;epitaxially induced strains;internal nitridation;oxide films;cu2o;films;growth;copper;creep;faces;sulfur

异步累积叠轧超细孪晶铜织构取向的演变

周蕾 , 史庆南 , 蔡晓兰 , 王军丽

材料热处理学报

孪晶能够在保持铜材电导率基本不变的情况下提高铜材强度,异步叠轧制备出超细晶铜材,再结晶过程中形成大量超细孪晶,通过背散射电子衍射研究织构演变,异步叠轧变形后原料铜板中的退火孪晶织构组分{ 114} 〈221〉消失,形成大量剪切织构{001}＜ 〈110〉和铜型织构{112}＜ 〈111〉＞组分,再结晶退火过程中,逐渐形成新的织构组分:{113}＜ 〈141〉＞、{125}＜ 〈112〉＞、{221} 〈114〉,通过矩阵计算得出,其中{221}＜ 〈114〉＞组分实质上是异步叠轧形成的剪切织构再结晶退火时沿{111}面的镜面反映,而形成的孪晶取向.

关键词: 异步叠轧 , 铜 , 超细孪晶 , 织构

轧制方向对Ni47Ti44Nb9锻造板,热轧板及冷轧板织构影响

冯昭伟 , 米绪军 , 王江波 , 袁志山 , 缪卫东 , 周瑾

稀有金属材料与工程

采用XRD研究了Ni47Ti44Nb9锻造板坯织构、不同热轧、冷轧方向板材织构.研究表明,锻造板坯有典型的γ取向线织构,锻板心部最强取向在{111}<112>.沿轧向(RD)、交叉方向(CD)、横向(TD)热轧板织构类型相似,主要有3条取向线织构,接近{ll4}、{223}、{332}(或{221}),{332}面织构取向密度最强,最强织构分别为{221}<110>、{332}<113>、{332}<023>,不出现γ-织构.沿与轧向成0°、45°、90°方向二次冷轧最强织构近似为{332}<110>.90°方向二次冷轧织构强度最高,有多个强织构组分,γ-织构得到显著加强.

关键词: Ni47Ti44Nb9形状记忆合金 , 织构 , 轧制方向 , 热轧板 , 冷轧板

一种微乳酸体系的实验室研究

陈馥 , 李茜璐 , 艾加伟 , 陈红均 , 魏云锦

应用化学 doi:10.3724/SP.J.1095.2011.00607

为降低酸化过程中酸液对油管和套管的腐蚀,增加酸液对地层的穿透距离,通过阳-非离子表面活性剂复配,成功制备了单相微乳土酸体系.并得出了较优的实验室配方(质量分数):A-126 2.5％,CHJ-102.5％,正丁醇1.2％,正辛醇2.3％,W-221 0.5％,土酸67.0％,柴油24.0％.通过添加适量的阴离子表面活性剂W-221,使体系在81℃保持了良好的热稳定性.在室温和70℃下分别与P110S钢片反应,与同浓度的土酸相比,缓蚀率达到90.57％.在70℃下与人造砂岩岩芯反应,溶蚀率降低到了0.5％.

关键词: 微乳酸 , 表面活性剂 , 缓蚀 , 耐温

1.08μmInAs/GaAs量子点激光器光学特性研究

钱家骏 , 叶小玲 , 徐波 , 韩勤 , 陈涌海 , 丁鼎 , 梁基本 , 刘峰奇 , 张金福 , 张秀兰 , 王占国

功能材料与器件学报 doi:10.3969/j.issn.1007-4252.2000.03.027

介绍了InAs/GaAs量子点激光器的材料生长,器件制备及其光学特性的研究.器件为条宽100μm,腔长1600μm未镀膜激器.室温阈值电流密度为221A/cm2,激射波长为1.08μm,连续波工作最大光功率输出为2.74W(双面),外微分效率为88%,经50oC,1000h老化,仍有>1.2W的光功率输出.

关键词: InAs/GaAs应变自组装量子点材料 , 量子点激光器 , 电致发光谱(EL) , MBE外延生长

NiTi形状记忆合金相变过程的正电子湮没研究

邓文 , 胡益丰 , 岳丽 , 郝文博 , 黄乐 , 黄宇阳 , 熊良钺

低温物理学报 doi:10.3969/j.issn.1000-3258.2006.03.008

采用正电子湮没技术研究了NiTi合金在降温和升温过程中缺陷和电子密度随温度的变化.在降温过程中,当温度从295K降至225K时,合金的电子密度nb随温度的降低而下降,在225K时降至最小;随后,nb随温度的降低而升高.当温度从295K降至221K时,合金缺陷的开空间随温度的下降而升高,在221K时达到最大值;随后,缺陷的开空间随温度的下降而下降.在升温过程中,当温度从25K升至253K时,合金的电子密度nb随温度的升高而降低,并在253K时达到最小;当温度从253K升至295K时,合金电子密度nb随温度的升高而升高.在相变临界温度点Ms=222K,Mf=197.2K,A,=237.5K,Af=255.5K附近,合金的电子密度nb及合金缺陷的开空间均有异常的变化.

关键词: NiTi合金 , 微观缺陷 , 电子密度 , 马氏体相变 , 正电子湮没

石榴子石晶体碱腐蚀像及其与酸腐蚀像的对比

刘河清 , 赵珊茸 , 徐畅 , 李坤

人工晶体学报

本文采用NaOH-KOH混合熔融物和KOH溶液对石榴子石晶体各种不同的结晶学方向的晶面(切面)进行腐蚀实验,建立了石榴子石碱腐蚀像的立体模型,并与酸(HF溶液)腐蚀像模型进行对比.研究发现碱腐蚀像与酸腐蚀像一样能很好的反映晶体的对称特点,并发现在{ 100}、{110}晶面(切面)上碱腐蚀像与酸腐蚀像相同,而在{120}、{221}、{111}、{211}晶面(切面)上,碱腐蚀像与酸腐蚀像不同.该研究可以用来对石榴子石族矿物进行结晶学定向,同时具有揭示矿物所处地质环境酸碱性的指示意义.

关键词: 石榴子石 , 腐蚀像 , 晶体定向

射频磁控溅射制备p-Bi2Te3热电薄膜的电学性能研究

穆武第 , 程海峰 , 唐耿平 , 陈朝晖

材料导报

通过射频磁控溅射并控制溅射时间在玻璃基底上沉积了不同厚度和成分的p型Bi2Te3薄膜.Bi2Te3薄膜主要以(221)晶面平行于基底进行生长,先在基底形成大量微小晶粒,合并长大成典型的纤维状组织结构;退火后薄膜沿平面方向形成片状结构.薄膜的电导率和Seebeck系数受薄膜厚度和成分的影响,退火前受薄膜厚度的影响较大,退火后受薄膜成分和均匀性的影响较大,自掺杂Bi质量分数在5%左右时,薄膜功率因子约为760μW/(K2·m).

关键词: 射频磁控溅射 , p-Bi2Te3 , 电导率 , Seebeck系数