ZH Tu
,
Z Zhang
,
L.Z. Zhaoand T.X. Mao (Cryogenic Laboratory
,
Chinese Academy of Sciences
,
Beijing 100080
,
China) (Institute of Mechanics
,
Chinese Academy of Sciences
,
Beijing 100080
,
China )
金属学报(英文版)
The mechanical properties of a type of Al-alloy weld including strength, fracture tough-ness and ductility were comprehensively studied at different temperatures. The frac-ture behavior and weld micro features were also characterized. The surface crack test method was adopted to study the fracture toughness and a multiple specimen test ap-paratus was designed to perform the cryogenic experiments. The relationship between the mechanical properties and temperature was obtained together with the fracture toughness distribution in the weld.
关键词:
Al-alloy weld
,
null
,
null
,
null
Metallurgical Transactions a-Physical Metallurgy and Materials Science
An investigation has been made of the fatigue and fracture behavior of an Al-Li-Cu-Mg-Zr 8090-T6 alloy at room (300 K) and liquid nitrogen (77 K) temperatures. The fatigue and fracture strengths, as well as ductility of the alloy, have been found to increase with decreasing temperature. The observations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveal that the changes in fatigue and fracture behavior with temperature are considered to be associated with the change in the deformation and fracture modes. It has been found that the occurrence of the localized shear deformation bands in which the hard precipitates are sheared by moving dislocations is responsible for the reduction of fatigue and fracture strengths as well as ductility of the alloy at room temperature. However, the improvement of both strength and ductility of the alloy at liquid nitrogen temperature might be attributed to the deeper and larger delamination that occurred on the fracture surface.
关键词:
al-li alloys;x alloys;toughness;2090-t8e41;deformation
李梦佳
,
陈普会
,
孔斌
,
彭涛
,
姚正兰
,
邱学仕
复合材料学报
doi:10.13801/j.cnki.fhclxb.20150930.002
在关于拉脱载荷下Z-pin增强T型接头的有限元模拟方法基础上,通过对2组蒙皮厚度分别为7.2 mm和4.0 mm的试验件的试验结果进行分析,研究了T型接头蒙皮厚度对 Z-pin增强效果的影响。结果表明：Z-pin增强效果随着蒙皮厚度的减小而增大。蒙皮厚度大于5 mm,Z-pin不能提高结构的最大承载能力,但可显著提高结构首次掉载后的承载性能,使T型接头在较大的加载位移下仍保持较高的承载能力；无论蒙皮厚薄,结构首次掉载后,各Z-pin增强T型接头可达到的载荷平台是相当的,且该载荷平台随蒙皮的变厚有降低的趋势。
关键词:
复合材料
,
T型接头
,
Z-pin
,
蒙皮厚度
,
有限元模拟
材料科学技术（英）
The method of high-pressure hydrogen charging was used to investigate the internal hydrogen effects on cryogenic mechanical properties of two Cr-Ni-Mn-N austenitic steels, 22-13-5 and 21-6-9. Specimens saturated with hydrogen up to 65x10(-6) similar to 68x10(-6) were tested in air at temperatures ranging from 77 to 293 K. Hydrogen caused the increase in cryogenic strength. both yield strength and ultimate tensile strength. Hydrogen decreased cryogenic ductility, and the maximum hydrogen embrittlement (HE) tendency was found at a certain low temperature. Cr-Ni-Mn-N austenitic steels showed the feature: delta(L) > psi(L) at low temperatures, here, delta(L) and psi(L) are the hydrogen induced loss rates of elongation and reduction of area, respectively Hydrogen had less effect on cryogenic Charpy impact toughness and notched tensile strength, however, hydrogen decreased cryogenic fracture toughness of the steels. At temperature below Md, the fracture toughness was obviously decreased due to the formation of strain-induced martensites, whether hydrogen was charged or not.
关键词:
李梦佳
,
陈普会
,
孔斌
,
彭涛
,
姚正兰
,
邱学仕
复合材料学报
doi:10.13801/j.cnki.fhclxb.201502.002
利用二维平面应变模型对Z-pin增强T型接头试样进行失效分析,采用内聚力模型模拟界面的破坏情况,通过在分层的上下界面加入非线性弹簧元模拟Z-pin的增强作用,非线性弹簧元的力学性能(桥联律)由细观力学方法获得,数值结果与试验值吻合较好.在已验证有限元方法的基础上,研究了Z-pin直径、密度及植入角度等对T型接头拉脱承载能力的影响.结果表明:Z-pin增强可显著提高T型接头的拉脱承载能力,与未Z-pin增强的T型接头相比,Z-pin增强明显延缓了掉载;T型接头的拉脱承载能力随Z-pin直径和密度的增加而增大,随植入角度的增大而减小;在所研究的角度范围内,当植入角度为60°时,T型接头的拉脱承载能力最好;Z-pin直径和密度对拉脱承载能力的影响远比植入角度的影响显著.
关键词:
复合材料
,
T型接头
,
Z-pin
,
非线性弹簧
,
桥联律
李成虎
,
燕瑛
复合材料学报
提出了基于z-pin桥联力试验的z-pin增强复合材料T型接头层间性能的模拟方法.每根z-pin的作用有两部分:增加了分层的张开阻力与剪切阻力.在有限元模拟中通过在相应的节点上加两个方向(竖直方向和水平方向)的非线性弹簧模拟张开阻力和剪切阻力.通过张开型z-pin桥联力试验和剪切型z-pin桥联力试验得到两条力-位移曲线,再把曲线各自赋予到所有竖直非线性弹簧和水平非线性弹簧,从而模拟z-pin对复合材料T型接头层间性能的增强效果.在T型接头拉拔试验模拟分析中,研究了不同跨距和不同z-pin间距对拉拔力的影响.模拟分析表明跨距对拉脱位移影响较大,z-pin间距对最大拉拔力影响较大.
关键词:
z-pin
,
复合材料
,
z-pin桥联力
,
张开型
,
剪切型
,
非线性弹簧
Materials and Corrosion-Werkstoffe Und Korrosion
Micro-arc oxidation (MAO) has been accomplished on Mg-Li alloy in alkaline polyphosphate electrolytes without and with the addition of 10?g/L?K2TiF6. The surface/cross-section microstructures of the fabricated coatings were analyzed by scanning electron microscope (SEM); the compositions of the fabricated MAO coatings were analyzed by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDAX); the corrosion behaviors of bare and MAO coated Mg-Li alloys were evaluated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) in 3.5?wt% NaCl solution. Novel hybrid MAO coatings which showed hybrid composition of MgF2/Ti2O5/Ti6O11/MgO, as well as hybrid structure of a dense inner layer, a dense outer layer and an intermediate layer with some sealed/semi-sealed pores, had been fabricated on Mg-Li alloy in alkaline polyphosphate electrolytes with the addition of K2TiF6. Meanwhile, the corrosion resistance of the fabricated MAO coatings was improved obviously as the result of the addition of K2TiF6 in the electrolytes. Moreover, the multiple roles of ${\rm TiF}_{{\rm 6}}boolean AND{{\rm 2}{-} } $ on the MAO process accounted for the fabrication of the corrosion-resistant hybrid MAO coatings.
关键词:
corrosion resistance;Mg-Li alloy;micro-arc oxidation;az91d magnesium alloy;corrosion-resistance;phosphate electrolytes;ceramic coatings;zn alloy;silicate;performance;aluminum;behavior
张立春
,
何安强
,
吴玉琨
,
叶恒强
,
张永昌
金属学报
利用高分辨电镜(HRTEM)和常规电子显微术研究了快速凝固Al-Li-Cu—Mg—Zr合金中Z相和T相的结构关系,发现两相间两种确定的晶体学取向关系,并以此为依据解释了Z相和T相的某些结构缺陷两相的结构有密切关联,其中一相中缺陷的扩展会导致另一相的形成
关键词:
Al-Li-Cu-Mg-Zr合金
,
Z hexagonal phase
,
T f.c.c. phase
,
shear structure
杜龙
,
矫桂琼
,
黄涛
,
赵龙
,
黄峰
复合材料学报
doi:10.3321/j.issn:1000-3851.2007.06.024
通过不同Z-pin角度(15°和25°)和夹芯厚度(8mm和12.7mm)的X状Z-pin增强泡沫夹层材料的剪切性能试验,与相同材料同尺寸的未增强件进行对比,考察X状Z-pin对泡沫夹层结构的增强作用.试验结果表明,X状Z-pin增强使材料的剪切强度和刚度都有较大幅度的提高;同时,Z-pin的加入使该结构具有与传统泡沫夹层材料不同的剪切破坏形式.在此基础上,结合空间网架结构和等效夹杂方法,提出了X状Z-pin增强泡沫夹层结构剪切刚度模型,计算结果与试验值符合良好.结果表明,X状Z-pin增强不仅能大幅度提高泡沫夹层结构的剪切性能,并具有良好的可设计性,可以通过改变Z-pin角度和材料等改变其力学性能.
关键词:
夹层结构
,
Z-pin增强
,
剪切性能
徐祥
,
杨明
,
梁益龙
,
张世伟
,
龚乾江
材料导报
doi:10.11896/j.issn.1005-023X.2016.18.030
在Gleeble-3500热模拟试验机上对211Z.X耐热高强韧铝合金进行了等温热压缩实验,实验的应变温度为350～500℃、应变速率为0.01～10 s-1.研究了不同变形条件下的流变特征,并分析该合金高温变形时流变应力的规律,构建了材料流变应力本构模型;同时基于动态材料模型建立了加工图,确立了该合金在实验条件的最佳工艺参数.结果显示:功率耗散图与失稳图随应变量的增加而变化,功率耗散峰区由3个逐渐减为1个,失稳区域随应变而移动并逐渐增大;在加工图中,随着应变的增大,安全加工区域逐渐减小.综合加工图与微观组织的分析结果,211Z.X铝合金最佳的加工工艺区间为:变形温度485～500℃、应变速率0.03～10 s-1.
关键词:
211Z.X耐热高强韧铝合金
,
热压缩变形
,
加工图
