Al－Cu合金G．P．区异常快速形成的复合体机制

用置换溶质原子－空位复合体机制，对Ａｌ－Ｃｕ合金Ｇ．Ｐ．区异常快速形成及相应的现象进行了解释，并与过剩空位机制和位错机制进行了比较。     

含Zn，Ag或Sc的Al－Li－Cu－Mg－Zr合金正电子寿命谱研究

在深低温到室温的不同温度下，测量了不同时效状态的Ａｌ－Ｌｉ－Ｃｕ－Ｍｇ－Ｚｒ合金和含Ｚｎ，Ａｇ或Ｓｃ的Ａｌ－Ｌｉ－Ｃｕ－Ｍｇ－Ｚｒ合金的正电子寿命谱。对ｅ＋寿命谱特征参数的分析表明：峰值时效使热空位大量回复，缺陷的数目减少。在深低温下，空位主要以单空位形式存在且随温度升高而激活并运动复合成多空位。Ｚｎ或Ａｇ的加入对空位的运动复合有束缚作用，而Ｓｃ却有助于空位的运动复合。所有实验样品低温下基体电子密度都比室温的高，δ＇相析出长大使合金基体的电子密度提高，而Ｓ＇相析出则使合金基体的电子密度降低。Ｚｎ，Ａｇ或Ｓｃ的加入都增加了基体电子密度，有利于合金强度的提高。     

CuO／CeO2体系中表面Cu（Ⅱ）组份的状态及还原过程

采用ＴＰＲ结合ＸＲＤ定理研究了ＣｕＯ／ＣｅＯ２体系中Ｃｕ（Ⅱ）的分散状态及还原过程，结果表明：ＣｕＯ在ＣｅＯ２表面的分散容量为１．１５ｍｍｏｌ／１００ｍ＾２，Ｃｕ（Ⅱ）可以以高分散态Ｃｕ（Ⅱ?嵌入到表面空位中以晶相ＣｕＯ（当ＣｕＯ含量超过分散容量时）形式存在，在还朱过程中首先是处于表面空位中的Ｃｕ（Ⅱ）被还原，随后晶相ＣｕＯ中的Ｃｕ（Ⅱ）进入该空位再被还原，从而导致表面连续嵌入和还原过程的发生。     

含Zn,Ag或Sc的Al-Li-Cu-Mg-Zr合金正电子寿命谱研究

在深低温到室温的不同温度下，测量了不同时效状态的Ａｌ－Ｌｉ－Ｃｕ－Ｍｇ－Ｚｒ合金和含Ｚｎ，Ａｇ或Ｓｃ的Ａｌ－Ｌｉ－Ｃｕ－Ｍｇ－Ｚｒ合金的正电子寿命谱，对ｅ＾＋寿命谱特征参数的分析表明，峰值时的使热空位大量回复，缺陷的数目减少，在深低温下，空位主要以单空位形式存在且随温度升高而激活运动复合成多空位，Ｚｎ或Ａｇ的加入对空间的运动复合有束缚作用，而Ｓｃ却有助于空位的运动复合，所有实验样品低温下基体电子密     

电化学制备Ni—Cu／Cu超晶格多层膜

采用单槽双脉冲恒电位制备了超晶格Ｎｉ－Ｃｕ／Ｃｕ多层膜,测试结果表明：Ｎｉ－Ｃｕ层与Ｃｕ层间界面清晰,各层均匀连续相互覆盖,具有良好的周期结构,Ｎｉ－Ｃｕ４．６ｎｍ／Ｃｕ３．４ｎｍ具有良好外延生长的超晶格结构,铜－镍生长的择优了向面为（１１１）晶面,该材料表现出特殊的阳极溶解性能。     

基片温度对Cu—TiC复合薄膜的影响

研究了基片温度对Ｃｕ－ＴｉＣ复合薄膜的影响。Ｃｕ－ＴｉＣ复合薄膜采用多靶磁控溅射仪制备。测定了薄膜的显微硬度及电阻率，并利用ＸＲＤ，ＳＥＭ，ＥＤＡＸ和ＴＥＭ研究了薄膜结构。结果表明，随基片温度的提高，Ｃｕ－ＴｉＣ复合薄膜中ＴｉＣ含量增加，Ｃｕ和ＴｉＣ的晶化逐步完善。     

扩散温度对Cu－Sn粉末压制与烧结性能的影响

热扩散法是制取部分合金化Ｃｕ－Ｓｎ粉末的途径之一，作者研究了扩散温度对Ｃｕ－Ｓｎ粉末压制与烧结性能的影响，实验结果表明，Ｃｕ－Ｓｎ粉末的压实性及烧结胀大现象，都随着扩散温度的提高而降低，Ｃｕ粉颗粒越粗，获得具有相同烧结性能的Ｃｕ－Ｓｎ粉末的扩散温度越高。     

氧化铈对Cu－Mn－O燃烧催化剂氧化还原性能的影响

利用微反－色谱技术考察了Ｃｕ－Ｍｎ－Ｏ及Ｃｕ－Ｍｎ－Ｃｅ－Ｏ催化剂的甲苯完全燃烧活性；通过改变氧的浓度，研究了ＣｅＯ＿２对Ｃｕ－Ｍｎ－Ｏ催化剂性能的影响；用ＴＰＲ、ＴＰＯＴ和氢氧滴定法测定了催化剂的表面性能。结果表明，ＣｅＯ＿２能够增加催化剂表面的贮氧量，提高吸氧能力，改进供氧性能，进而提高Ｃｕ－Ｍｎ－Ｏ催化剂在低氧比时的无化活性，也能使还原后的Ｃｕ－Ｍｎ－Ｏ催化剂具有良好的再生氧化活性。     

合金元素对一种多元合金钢可逆回火脆性的影响

研究了合金元素对一种多元合金钢可逆回火脆性的影响。结果表明，产生可逆回 火脆性的温度范围是４００～５５０℃．主要原因是Ｐ在晶界上的偏聚．沿晶单位面 积的断裂功与Ｐ的偏聚量有Ａｋ＝０．４４－３．４Ｊ／ｍｍ２关系。式中，为Ｐ在 积的断裂功与Ｐ的偏聚量有Ａｋ＝０．４４－３．４ＹＪ／ｍｍ２关系。式中为Ｐ在 晶界偏聚位置分数。阶梯回火不但加速了Ｐ的偏聚速度，而且提高了平衡偏聚量。 合金中的Ｃ排斥Ｐ，并且Ｃ本身有增强晶界结合力的作用，因此适量的Ｃ对防止 可逆回火脆性是有好处的；Ｃｒ有明显促进Ｐ在晶界偏聚的作用．其原因足Ｃｒ与 Ｃ之间交互作用较强；Ｍｎ，Ｎｉ，Ｃｕ山于都会促进Ｐ在晶界的偏聚，所以不同程 度的促进了可逆回火脆性。     

Cu 短纤维制得的 DG 复合材料

采用粉末冶金方法制得了ＦｅＮｉ／Ｃｕ粉末和ＦｅＮｉ／Ｃｕ纤维的低膨胀高导热（ＤＧ）复合材料．结果表明，随着Ｃｕ粉末尺寸增大，ＦｅＮｉ／Ｃｕ粉末制品电阻率减小，膨胀系数增大；而随着Ｃｕ纤维长径比增大，ＦｅＮｉ／Ｃｕ纤维制品的热膨胀系数和电阻率都增大．这是由Ｃｕ纤维和Ｃｕ粉末在制品中的分布状态，即Ｃｕ网络形成难易程度和ＦｅＮｉ与Ｃｕ互扩散难易程度共同决定的．当膨胀系数小于７×１０－６／Ｋ时，ＦｅＮｉ／Ｃｕ纤维制品比ＦｅＮｉ／Ｃｕ粉末制品的电导性能要好．     

Enhanced nanocrystalline stability of BCC iron via copper segregation

Nanocrystalline alloys are known for their high density of grain boundaries (GBs), which results in low thermal stability and a tendency for coarsening. In this work, we investigated Fe–Cu alloys to explore the effects of Cu concentration on the thermal stability of nanocrystalline samples. Using hybrid molecular dynamics (MD) and Monte Carlo (MC) simulations, annealing treatments of nanocrystalline samples with varied Cu concentrations were conducted. The simulation results revealed that Cu atoms tended to accumulate at GBs. Subsequently, the model with Cu segregation was subjected to mechanical creep loading at various temperatures. Through the analysis of atomic structure evolution during creep deformation, it was found that Cu segregation efficiently stabilizes GBs and restricts their movement. The present findings highlight that the thermal stability of nanocrystalline Fe–Cu alloys can be effectively improved by introducing suitable Cu segregation at GBs.     

Effect of Cu surface segregation on the exchange coupling field of NiFe/FeMn bilayers

The NiFe/FeMn bilayers with different buffer layers (Ta or Ta/Cu) were prepared by magnetron sputtering. Results show that the exchange coupling field of NiFe/FeMn films with Ta buffer is higher than that of the films with Ta/ Cu buffer. We analysed the reasons by investigating the crystallographic texture, surface roughness and surface segregation of both films, respectively. We found that the decrease of the exchange coupling fields of NiFe/FeMn films with Ta/ Cu buffer layers was mainly caused by the Cu surface segregation on NiFe surface.     

稀土元素对耐候钢元素偏析的影响

应用金属原位统计分布分析技术(OPA)研究了耐候钢铸锭中C、P、S、Cu、Si和Mn的宏观偏析规律,并分析了稀土元素对耐候钢中元素偏析的影响.结果表明,在30%～40%等轴晶率,20℃过热度下,元素C、S、P和Cu能产生严重的宏观偏析,C、S呈中心正偏析,P、Cu呈中心负偏析并伴随有反偏析,而Si和Mn的分布较为均匀.各个元素中心偏析位置完全相同.稀土元素在钢中的固溶度为10-5～10-4,固溶稀土元素可以细化枝晶,提高等轴晶率.钢中加入质量分数0.38%～0.55%的稀土元素可以有效改善C、S、P和Cu的宏观偏析.     

掺Cu对O吸附RhxPt1-x合金(110)表面偏析的影响

应用计算机编程构造出了考虑和不考虑吸附与偏析相互作用情况下无序二元合金RhxPt1-x(110)表面的原子集团模型(O的覆盖度为0.5).考虑掺Cu对合金表面产生影响的原子集团模型,Cu的掺入采用替位式,即将O的最近邻的Rh替换为Cu.应用Recursion方法计算了掺Cu对O吸附情况下RhxPt1-x无序二元合金(110)表面的电子结构,由此得出:1)Rh0.7Pt0.3合金表面存在着Rh偏析,掺Cu使合金表面偏析情况发生逆转;2)掺Cu后,Cu使Rh与O的共价相互作用减弱,进而降低了合金表面的总态密度.     

Al-Cu-Mg合金时效初期的价电子结构分析

运用固体与分子经验电子理论(EET),计算了A l-Cu-Mg合金时效初期的偏聚晶胞及其GPB区的价电子结构,并从价电子结构层次分析了A l-Cu-Mg合金时效初期的各种晶胞对合金性能的影响.结果表明:在含有Cu和Mg的偏聚晶胞中,GPB区具有较强的共价键络,能够提高合金的整体强度;在含有空位的偏聚晶胞中,Mg原子的杂阶能级偏低,该晶胞易成为后续析出相的形核胚芽.     

Microscopic characterization of semi-solid aluminium alloys

The microstructural evolution and element distribution of the Al-4Cu-Mg alloy during semi-solid compression were investigated, and the precipitate behavior and dislocation morphology were discussed. The experimental results show that the microstructure, the number of CuAl₂ (θ phase) precipitates, and the dislocation density of the Al-4Cu-Mg alloy depend apparently on the process parameters. More segregation of Cu at the grain boundary happens with an increase of deformation temperature and a decrease of strain rate, leading to an increase in the number of θ phase. With an increase of height reduction, Cu segregation at the grain boundary decreases gradually. Moreover, unique dislocation morphologies including helical dislocations and dislocation loops appear at different process parameters and evolve to reduce the stored energy.     

Bismuth embrittlement of copper is an atomic size effect

Embrittlement by the segregation of impurity elements to grain boundaries is one of a small number of phenomena that can lead to metallurgical failure by fast fracture. Here we settle a question that has been debated for over a hundred years: how can minute traces of bismuth in copper cause this ductile metal to fail in a brittle manner? Three hypotheses for Bi embrittlement of Cu exist: two assign an electronic effect to either a strengthening or weakening of bonds, the third postulates a simple atomic size effect. Here we report first principles quantum mechanical calculations that allow us to reject the electronic hypotheses, while supporting a size effect. We show that upon segregation to the grain boundary, the large Bi atoms weaken the interatomic bonding by pushing apart the Cu atoms at the interface. The resolution of the mechanism underlying grain boundary weakening should be relevant for all cases of embrittlement by oversize impurities.     

Al-Cu-Mn合金铸锭均匀化工艺及组织性能分析

采用光学金相显微镜、扫描电子显微镜及能谱分析、电导率等检测手段,对铸态和均匀化态的2219合金微观组织、第二相分布及电导率进行研究分析。结果表明,2219合金铸态组织存在着枝晶偏析,在晶界上聚集大量的Al₂Cu相,并有长条状的脆性相Al₇Cu₂（Fe、Mn）穿插在晶界上。经525 ℃均匀化处理22 h后,晶界上Al₂Cu相回溶到基体中,枝晶网络被破坏,枝晶偏析消除,Cu元素从晶界到晶内的分布趋于平稳;处于亚稳态的溶质原子从过饱和固溶体中析出,在晶内呈细小、弥散地分布,基体溶质原子固溶度降低,电子散射作用减弱,电导率提高10 %IACS。     

The precipitation strengthening behavior of Cu-rich phase in Nb contained advanced Fe–Cr–Ni type austenitic heat resistant steel for USC power plant application

Copper has been used as a strengthening element in newly developed Fe–Cr–Ni type austenitic heat resistant steel for inducing Cu-rich phase precipitation to meet high temperature strength requirement for 60°C Ultra Super-Critical (USC) coal fired power plants for many years. However, the precipitation behavior and strengthening mechanism of Cu-rich phase in these advanced austenitic heat resistant steels is still unclear. In order to understand the precipitation strengthening behavior of Cu-rich phase and to promote high strength austenitic heat resistant steel development, 18Cr9 NiCuNb steel which is a Cu-added Nb contained advanced Fe–Cr–Ni type austenitic heat resistant steel has been selected for this study to be aged at 650°C till to 10,000 h. Micro-hardness and room temperature tensile test were conducted after long-time aging. SEM,TEM, HRTEM and three dimensional atom probe (3DAP) technology accompanying with thermodynamic calculation have been used to investigate the Cu-rich phase precipitation behavior during 650°C aging. The experimental results showed that Cu atoms can quickly concentrate in clusters at very early precipitation stage to form the fine nano-size Cu-rich ‘‘segregation areas’within less than 1 h at 650°C. With increasing aging time at 650°C Cu atoms continuously concentrate to Cu-rich segregation areas (clusters) and simultaneously other kinds of atoms such as Fe, Cr and Ni diffuse away from Cu-rich segregation areas to austenitic matrix, and finally to complete the transformation from Cu-rich segregation areas to Cu-rich phase. However, there is only Cu atoms concentration but not crystallographic transformation from early stage of Cu-rich clusters forming to the final Cu-rich phase formation. Even the Cu atom becomes the main composed element after 500 h aging at 650°C the Cu-rich phase still keeps coherent relationship with austenitic matrix. According the experimental results in this study, Cu-rich phase precipitation sequence which starts from the Cu atom segregation followed by the Cu diffusing from matrix to segregation areas and Fe, Cr and Ni atoms diffuse out from Cu-rich areas to matrix without crystallographic transformation is proposed. The Cu-rich phase is the most dispersed phase and contributes the most important strengthening effect among all precipitated phases (M23C6, MX and Cu-rich phase). It has been found that Cu-rich phase is very stable and still keeps in nano-size even for 10,000 h aging at 650°C. The unique precipitation strengthening of Cu-rich phase in combination with nano-size Nb-rich MX phase and grain-boundary M23C6carbide contributes excellent strengthening effect to 18Cr9 NiCuNb austenitic heat resistant steel.     

表面活性剂Bi对自旋阀多层膜交换耦合场的影响及其微结构分析

采用磁控溅射方法制备了Ta(10nm)/NiFe(8nm)/Cu(2.6nm)/NiFe(3.6nm)/FeMn(9nm)/Ta(10nm)自旋阀多层膜.在Cu/NiFe界面沉积适量厚度的Bi原子能够有效地提高交换耦合场,沉积过量的Bi原子会导致交换耦合场下降.X射线光电子能谱分析结果表明:沉积在Cu/NiFe界面的Bi原子可以有效地抑制Cu原子在NiFe层表面的偏聚;当沉积过量的Bi原子时,Bi原子会进一步迁移到FeMn中,形成杂质,从而破坏了FeMn的反铁磁性,使交换耦合场降低.