S.Billard
,
E.Meslin
,
G.F.Dirras
,
J.P.Fondère
,
B.Bacroix
材料科学技术（英文）
Commercial purity Al has been processed by hot isostatic pressing consolidation of nanopowders. The resulting bulk material contained a small fraction of microcrystalline grains (>300 nm) embedded in a matrix of ultrafine grains (150 nm). The mechanical properties under compressive tests at various temperatures and at a strain rate of 2×10－4 s－1 have been investigated. At room temperature a brief hardening was observed followed by a stagnation of the flow stress up to failure. From 150 to 200℃ softening occurred after a short hardening stage. A change in the behavior showed up at 300℃: a quasi perfect plasticity was observed subsequently to a yield point. The major deformation mechanisms include dynamic recovery, grain fragmentation and sliding. Besides, when tested up to rupture at elevated temperature filament formation where observed at the fracture surface. The formation mechanism of the filaments is possibly linked to the presence of a viscous-like phase at grain boundaries.
关键词:
Aluminum
,
null
,
null
,
null
张军
,
孙学峰
,
赵霞
,
李晓光
低温物理学报
doi:10.3969/j.issn.1000-3258.1999.04.010
本文研究了Hg0.7Cr0.3Sr2Ca2Cu3Oy, HgBa2Ca2Cu2.9Re0.1Oy, HgSr2Ca3Cu3.8}Re0.2Oy的磁性,发现Re的掺入会改变U-J关系.由驰豫测量结果分析得到Hg(Re)-1223,Hg(Re)-1234具有对数钉扎势U=U0H-nln(Jc0/J),其中对Hg(Re)-1223在20K～60K范围里U0和Jc0近似与温度无关; 对Hg(Re)-1234,U0和Jc0与磁场和温度有关.而Hg-1223具有幂次方钉扎势U=U0(Jc0/J)μ.另外,由磁化曲线M(H)的测量得到临界电流密度随磁场的变化关系.结果表明Hg(Re)-1223在20K～90K、Hg(Re)-1234在20K～70K的温度范围内,临界电流密度随磁场的变化关系均可以用由对数钉扎势得出的Jc(H)关系很好地描述.我们认为Re掺入引起的体系的各向异性的减小和岛状钉扎中心,使得材料钉扎能力增强并引起U-J关系的变化.
关键词:
郭宏海
,
宋波
,
候立松
,
毛璟红
,
赵沛
稀土
doi:10.3969/j.issn.1004-0277.2011.02.012
研究了在不同冷速下添加RE对耐候钢中P元素宏观偏析的影响.研究发现,在钢中添加0.060%～0.380%量的RE,其固溶量可以达到0.006%～0.017%,这部分固溶稀土可以起到微合金化的作用,能够明显细化枝晶,增加等轴晶率,可以明显改善耐候钢中P元素的宏观偏析.继续加入过量的RE并不能提高其固溶含量.
关键词:
耐候钢
,
磷偏析
,
稀土
MI Fengyi
,
WANG Xiangdong
,
LIU Zhipu
,
WANG Bing
,
PENG Yun
,
TAO Dongping
钢铁研究学报(英文版)
The corrosion behavior of lowcarbon steel (CS), Pbearing steel (PS) and PRE weathering steel (PREWS) exposed for two years in Jiangjin of China was investigated. The results showed that during 2year exposure test, corrosion data of the experimental steels followed the bilogarithmic equation, and the average corrosion depth of PS and PREWS was decreased by 195% and 282% respectively compared with that of CS. Scanning electron microscope, electrochemical impedance spectroscope and Fourier transform infrared spectroscope were used to characterize the corrosion products. The research results showed that P in steel could promote the formation of an amorphous ferric oxyhydroxide layer near the substrate. The addition of RE could effectively increase the charge transportation resistance of rust.
关键词:
weathering steel
,
industrial atmosphere
,
rust layer
,
synergistic effect
王玲玲
,
唐黎明
,
黄桂芳
,
黄维清
,
彭军
,
稀有金属材料与工程
报道了从水溶液中电沉积稀土含量高于30%的Ni-RE-P(RE=Ce,Nd)合金,其中Ni-P,Ni-Ce-P及Ni-Nd-P合金镀层均为非晶态结构,玻璃化温度约为385℃;用DTA测定了3种合金的晶化活化能分别为:5233 kJ/mol. 574.4 kJ/mol,558.9 kJ/mol;利用二维Miedema坐标(△φ*和△n-1/3 ws)以及加入尺寸因素(△R/RA)构成的三维化学坐标分析了合金的非晶形成规律,探讨了实现稀土合金电沉积的途径,具体为:选择适当的络合剂、合适的电极材料及合适的共沉积元素.
关键词:
电沉积
,
稀土合金
,
非晶态
,
晶化动力学
,
非晶形成规律
朱佳庆
,
何俊伟
,
李云德
原子核物理评论
计算了pp和p碰撞中J/ψ的领头阶光生过程的产额。运用非相对论量子色动力学回顾了重夸克偶素产生的色单态机制与色八重态机制,并将它们分别用于处理直接光子过程和分解光子过程。通过与J/ψ产生的领头阶结果的对比可以看出,光生过程对J/ψ产额的修正在大横动量区域变得明显。
关键词:
光生过程
,
大横动量区域
,
重夸克偶素
Z.C. Guo
,
X.Y. Zhu
金属学报(英文版)
The effects of pulse frequency f and duty cycle r on the deposition rate, composition, morphology, and hardness of pulse electrodeposited RE (rare earth)-Ni-W-P-SiC composite coatings have been studied. The results indicate that pulse current can improve the deposition rate of RE-Ni-W-P-SiC composite coatings; W, P, and SiC contents in the coating decrease with the increase of pulse frequency and reach the lowest value at f = 33Hz, whereas the RE content in the composite coatings increases with increasing
pulse frequency. SiC content decreases with the increase of duty cycle, W content reaches the lowest value, and P content reaches the highest value at r = 0.4; pulse current and RE can lead to smaller size of the crystalline grains; however, the effects of different pulse frequency and duty cycle on the morphologies of RE-Ni-W-P-SiC composite coatings are not obvious. The hardness of
RE-Ni-W-P-SiC composite coatings is the highest when the duty cycle is at 0.6 and 0.8 and pulse frequency is at 50Hz. At the same pulse frequency, the hardness of RE-Ni-W-P-SiC composite coatings at r = 0.8 is higher than that at r = 0.6.
关键词:
pulse frequency
,
null
,
null
Z.C. Guo
,
X.Y. Zhu
,
R.D. Xu
金属学报(英文版)
Cathodic deposition current density of the composite coatings increases when SiC par-ticles and rare earth (RE) were added in the bath, which is profitable for Ni- W-P alloyto deposit in the cathod, forming Ni-W-P-SiC and RE-Ni-W-P-SiC composite coat-ings. On the contrary, the addition of PTFE in the bath decreases cathodic depositioncurrent density of the coatings. The current density increases a little when the amountof RE is 7-9g/l; however, the current density increases greatly when the amount ofRE is increased to 11-13g/l. But if the amount of RE is raised further, the currentdensity decreases. Hardness and wear resistance of RE-Ni-W-P-SiC composite coat-ing have been studied, and the results show that the hardness and wear resistance ofRE-Ni-W-P-SiC composite coating increase with increasing heat treatment tempera-ture, which reach peak values at 400℃; while the hardness and wear resistance of thecoating decrease with the rise of heat treated temperature continuously.
关键词:
electrodeposition
,
null
郭忠诚
,
陈凌
,
杨显万
,
翟大成
电镀与涂饰
doi:10.3969/j.issn.1004-227X.2000.03.001
研究了RE-Ni-W-P-B4C-PTFE复合镀层的性能.结果表明:热处理温度对RE-Ni-W-P-B4C-PTFE复合镀层的硬度影响很大,当温度达到400℃时,复合镀层的硬度达到极大值(1145 Hv);在同一热处理温度下,当保温时间达到3小时,镀层的硬度值最佳.当热处理温度达到300℃时,RE-Ni-W-P-B4C-PTFE复合镀层的耐磨性最好.高温氧化试验表明:RE-Ni-W-P-B4C-PTFE复合镀层随氧化时间和温度的延长,被氧化的程度增加.
关键词:
电沉积
,
RE-Ni-W-P-B4C-PTFE复合镀层
,
性能
