材料期刊网

MICROSTRUCTURE AND TENSILE PROPERTIES OF Fe3Al-BASED ALLOYS WITH VC AND TiC ADDITIONS

W.L.Xu , Y.S.Sun , S.S.Ding

金属学报(英文版)

Microstructure and tensile properties of Fe3Al-based alloys with additions of TiC andVC particles have been investigated.Results show that the formation of TiC particlesresults in the refinement of the macrostructure of as-cast ingots.Although the additionof VC particles does not cause significant change of the as-cast microstructure,themicrostructure of the alloy after hot-working and recrystallization has been found tobe refined.The formation of both VC and TiC particles results in the increase of yieldstrength,especially at high temperature of 600℃.

关键词: Fe3Al , null , null , null , null

试棒的w_0/l_0值对Zn-5%Al合金超塑性m-δ关系的影响

刘勤 , 裔式珙

材料研究学报

在250℃以■=0.025min~(-1)测到的Zn-5%Al 合金的超塑性m-δ曲线均属式。w_0/l_0值加大使m_0,m_L 和δ_F 值增大,但对δ_L 和m_F 值无大影响。试样厚度的加大(由1增大到2mm)仅使δ_L 和δ_F 值增大,考虑w_0/l_0比值的影响,C_3~((m_0-m_L))-(m_L=m_(mas))型C.L.m-δ方程式规划为:或其中,m′_0(W_0/l_0)=m_0,m′_0>m_0;m′_L(w_0/l_0)=m_L,m′_L>m。w_0/l_0=0.15—0.39。当w_O/l_0=1时,缺口效应消失,δ(或δ_F)值为最大。

关键词: Zn-5%Al合金 , mechanics of superplasticity , C.L.m-δequation

压力对L12-Co3(Al,W)化合物弹性性能与电子结构的影响

姚传生 , 陈铮 , 杜秀娟

稀有金属

基于密度泛函理论,采用第一性原理赝势平面波方法计算了不同压力下L12-Co3(Al,W)化合物的弹性性质与电子结构.计算得到零压力下的点阵常数a0与实验值和理论值相符,计算结果表明:在0～45 GPa压力范围内,L12-Co3(Al,W)化合物的弹性常数Cq (CH、C12、C44)与压力满足三阶多项式关系,体模量B、剪切模量G、本征塑性、断裂韧性随压力的增强而增加;通过引入总化学键重叠布局数,定量的计算了金属间化合物的共价键性能,结果显示压力的增加会不断增强L12-Co3(Al,W)化合物中的共价键强度;电荷差分密度分析表明,随着压力的增加,W原子得到电子,A1原子失去电子,Co-Co、Co-W原子间电荷密度明显增强,表现出更强的键合作用.

关键词: 密度泛函理论 , 弹性性能 , 电子结构 , 压力 , L12-Co3(Al,W)化合物

A comparison of the ideal strength between L1(2)Co(3)(Al,W) and Ni(3)Al under tension and shear from first-principles calculations

Applied Physics Letters

The ideal strengths of L1(2)Co(3)(Al,W) in comparison with Ni(3)Al are investigated using the first-principles method. Results for the stress-strain relationships, ideal tensile and shear strengths are presented. The calculated elastic properties agree well with the experimental observations. Co(3)(Al,W) is found to have larger moduli and higher strengths, but less ductile than Ni(3)Al. The electronic structures indicate the directional covalentlike Co-W bonding through d-d hybridization is the origin of excellent mechanical properties of Co(3)(Al,W).

关键词: ab initio calculations;aluminium alloys;cobalt alloys;ductility;elastic moduli;electronic structure;nickel alloys;shear strength;stress-strain relations;tungsten alloys;w-base alloys

316L不锈钢Ni-W-P非晶态化学镀层的耐腐蚀性能

郑志军 , 赵可昕 , 高岩

材料保护

为了弄清316L不锈钢Ni-W-P非晶态化学镀层的耐腐蚀性能,以模拟人工汗液和5.0%H2SO4溶液为腐蚀介质进行了阳极极化试验.结果发现,镀层厚度超过10μm时:(1)Ni-W-P非晶态化学镀层的耐蚀性能与316L不锈钢基本相当;(2)在前48时,Ni-W-P非晶态化学镀层耐汗液的抗变色能力也与316L不锈钢相近,但随着浸泡时间的延长,抗变色能力较316L不锈钢差.

关键词: 化学镀 , Ni-W-P非晶态镀层 , 不锈钢 , 耐腐蚀性能

Effect of W on structural stability of TiAl intermetallics and the site preference of W

Physical Review B

The effect of W on the structural stability of TiAl intermetallic systems and the site preference of W in B2 and L1(0) TiAl were studied based on first-principles calculations. It was found find that about 15 at. % W addition, in good agreement with experiment, is required to stabilize the B2 structure in a TiAl base alloy. W was predicted to occupy Al sites in the B2 phase, but Ti sites in the L1(0) phase. The B2-stabilizing effect of W and its site preference can be explained perfectly on the basis of the pseudogap effect and the strong covalent W-Ti bonding. The strong W-Ti bonding pairs are maximized when W occupies Al sites in B2 TiAl. But when W occupies Al sites in L1(0) TiAl, the W-Ti bonding is weakened by the existence of Al in the alternating (002) plane, which can, however, strengthen the in-plane W-Ti bonding when W occupies Ti sites.

关键词: gamma-titanium aluminides;electronic-structure;microstructure;deformation;systems;alloys

Professor XU Zhong-yu and his research activities

新型炭材料

关键词:

使用安捷伦J&W DB-35ms超高惰性色谱柱和DB-XLB色谱柱对水中低于μg·L-1级的有机氯农药和除草剂进行GC/μECD法分析

Doris Smith , Ken Lynam

环境化学

本文中使用安捷伦SPEC C18AR固相萃取膜盘成功萃取了水中的有机氯农药残留和除草剂.使用双柱配置的GC/μECD系统进行检测,安捷伦J&W DB-35ms UI超高惰性色谱柱作为分析柱,DB-XLB色谱柱为确认柱.该方法为浓度接近或低于最大污染限值的含氯有机物提供了高度灵敏的分析方法.根据预估的分析物萃取浓度,方法使用的校准范围为1-100 ng· mL-1.分别对0.01 μg·L-1的加标水样和一个自来水水样进行了萃取和分析,结果证明可满足水中的有机氯农药残留和除草剂的测定.

关键词: 有机氯农药 , 除草剂 , 色谱柱

METASTABLE CHARACTERISTICS OF β-W

HUANG Huimin CHEN Xinmin Central South University of Technology , Changsha , China HUANG Huimin Associate Professor , Department of Chemistry , Central South University of Technology , Changsha , China

金属学报(英文版)

The nature of the oxygen contained in β-W was investigated with DSC,X-ray analysis on quenched samples and Auger spectroscope.It was shown that the oxygen contained in nonpyrophoric β-W consists of the reversibly chemisorbed oxygen and the interstitial oxygen which could form an interstitial solid solution with β-W.It seems better to consider β-W to be a metastable phase of tungsten with the interstitial oxygen as stabilizer.

关键词: tungsten , null , null , null

代铬镀层--Ni-W、Ni-W-B非晶态合金镀层性能研究

朱立群 , 李卫平

电镀与涂饰 doi:10.3969/j.issn.1004-227X.2004.05.003

通过在浓硝酸、w=5% NaCl溶液、c＝1 mol/L H2SO4溶液中的浸渍试验,研究了不同基体上的Ni-W非晶态合金镀层的耐蚀性;通过测定在w=5% NaCl溶液及c=1 mol/L的HNO3溶液、H2SO4溶液、HCl溶液中的阳极极化曲线,研究了Ni-W非晶态合金镀层薄膜本身的耐蚀性;采用线性极化方法对Ni-W-B非晶态合金镀层在w=5% NaCl溶液、c＝1 mol/L H2SO4溶液及HNO3溶液中的腐蚀速度进行了测定,并测定了以上2种非晶态合金镀层的硬度与耐磨性.结果表明,非晶态的Ni-W、Ni-W-B镀层比晶态镀层的耐腐蚀性能要好,而Ni-W-B 非晶态合金镀层比Ni-W非晶态合金镀层的耐蚀性能又明显提高;经热处理后,Ni-W-B非晶态镀层的硬度值明显高于Ni-W非晶态镀层,耐磨性能都提高了1倍以上.Ni-W、Ni-W-B非晶态镀层极有望成为一种比较好的代铬镀层.

关键词: 代铬镀层 , 非晶态镀层 , Ni-W , Ni-W-B , 耐蚀性能