材料期刊网

SURFACE YIELD STRENGTH AND FATIGUE LIMIT FOR STEELS

WANG Hongwei MA Jinsheng NAN Junma HE Jiawen Xi′an Jiaotong University , Xi′an , China

金属学报(英文版)

The surface yield strength(σ_(ms))for various carbon steels was studied by means of X-ray diffraction method.The results showed that it is.far below the bulk yield strength,and is the resistance against plastic deformation in the surface layer.The smooth fatigue limit is associ- ated with crack initiation which is a result of accumulation of plastic deformation.Experimen- tal results showed the relation of smooth fatigue limit for 50% survival with σ_(ms)is σ_(ms)=0.81 tO 1.02 σ_(-1)for different steels.The smooth fatigue limit of a medium carbon steel for 99.9% survival with σ_(ms)is σ_(ms)=0.98 tO 1.10 σ_(-1).It is less expensive and time consuming to measure σ_(ms)than σ_(-1).

关键词: X-ray , null , null

FIELD-THEORY AT FINITE-TEMPERATURE AND ETA-XI-SPACETIME

Science in China Series a-Mathematics Physics Astronomy

The relation between eta-xi spacetime and the field theories at finite temperature is discussed.

关键词:

STATISTICAL EVALUATION OF CRITICAL INCLUSION FACTOR FOR SECONDARY RECRYSTALLIZATON IN 3%Si STEEL Lecturer,Department of Materials Engineering,Southwestern Jiaotong University,Chengdu 610031,China

LI Shuchen Southwestern Jiaotong University , Chengdu , ChinaCHEN Mengzhe KE Jun University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

On the basis of statistical data of MnS in the conventional 3% Si steel sheeets after various annealing processes,the critical inclusion factor has been evaluated to be 20 mm~(-1).The inhi- bition of MnS to grain growth has been exactly described.

关键词: 3%Si steel , null , null

采用NaN3燃烧合成高α相氮化硅粉体

王飞 , 沈卫平 , 葛昌纯

稀有金属材料与工程

采用燃烧合成方法,以NaN3作为固态氮化剂,制备了α相含量高达97%以上的氮化硅粉体.研究了外部氮气压力对于燃烧合成氮化硅粉体的影响.NaN3的加入主要是为燃烧合成反应提供了比N2分子更高化学活性的内部氮源(N3原子团和N原子),同时作为Si-N反应的催化剂,使Si粉在氮气中的燃烧合成反应更加容易进行.适量的NaN3加入能够促进Si粉的完全氮化并提高燃烧产物中的α-Si3N4含量.详细探讨了采用NaN3作为固态氮化剂条件下可能的氮化硅燃烧合成机理.

关键词: 燃烧合成 , NaN3 , 氮化硅

THERMAL NUCLEATION AND GROWTH OF He BUBBLES IN He IMPLANTED STAINLESS STEELS

ZHANG Lei WANG Peixuan TAO Rong MA Ruzhang ZHANG Guoguang University of Science and Technology Beijing , Beijing , China professor , Department of Materials Physics.University of Science and Technology Beijing.Beijing 100083 , China

金属学报(英文版)

Nucleation and growth of He bubbles at different annealing temperatures T≤1023 K in stain- less steels HR-2 and SS321,implanted with He~+(40-70 keV.1×10~(16)-6× 10~(17) He~+/cm~2),were ohserved under TEM.T=0.45T_m seems to be a transition temperature.The He bubbles continue mainly their nucleation at 0.3T_m< T<0.45T_m,and grow predominantly at T≥0.45T_m,due probably to migration and coalescence by surface diffusion of metal atoms around the bubbles.The apparent activation energies for the growth are found to he 0.41 and 0.31 eV for HR-2 and SS321 respectively.The bubble density in HR-2 is greater than that in SS321 within whole measuring temperature range,and the onset temperature of rapid swelling is also higher.It is believed that the resistance of HR-2 to He is superior to that fo SS321.

关键词: stainless steel , null , null , null , null

Two-step magnetization in a spin-chain system on the triangular lattice: Wang-Landau simulation

Physical Review B

The Wang-Landau algorithm is used to study the thermodynamic and magnetic properties of triangular spin-chain system based on two-dimensional Ising model in order to understand the magnetic-order dynamics in Ca(3)Co(2)O(6) compound. The calculated results demonstrate that the equilibrium state of the rigid spins produces the two-step magnetization curve at low temperature even when the random-exchange term is considered. This work indicates that the four-step magnetization behavior observed experimentally must be due to the nonequilibrium magnetization.

关键词: calcium compounds;exchange interactions (electron);Ising model;magnetisation;thermodynamics;one-dimensional ca3co2o6;density-of-states;compound ca3co2o6;phase-diagram;proteins;crystal

Fe-C-Xi多元合金系γ→α转变中PLE/NPLE转变温度的计算

盛广 , 杨志刚

金属学报 doi:10.3321/j.issn:0412-1961.2007.04.003

根据局部平衡模型,Fe-C-Xi合金系铁素体生长模式可以分为合金元素Xi扩散控制的再分配局域平衡模式(partition local equilibrium,PLE)和C元素扩散控制的不分配局部平衡模式(no partition local equilibrium,NPLE).在基本热力学模型的基础上,建立了简便计算Fe-C-Xi合金系PLE/NPLE转变温度的方法.代入合金原始成分,即可准确计算这一成分对应的PLE/NPLE转变温度.应用这一方法计算了多种Fe-C-Xi合金系的PLE/NPLE转变温度.

关键词: Fe-C-Xi合金系 , 铁素体 , 热力学 , PLE/NPLE转变温度

Fe-∑Xi-C合金系超组元模型Zener两参数的修正

彭宁琦 , 唐广波 , 刘正东 , 吴秀月

金属学报 doi:10.3321/j.issn:0412-1961.2009.03.013

根据Aaronson提出的超组元模型,借助Ae3的实验数据,提出了修正的置换型元素Xi(Xi=Si,Mn,Ni,Co,Mo,Al,Cu,Cr)的Zener两参数,修正中考虑了合金元素间的交互作用.修正后的超组元模型的预测精度明显改善:Ae3计算值与实验值的标准差为10.8℃,与Thermo-Calc计算值的标准差为2.35℃;Ae1计算值与实验值的标准差为6.8℃.按照马氏体相变热力学的计算方法,采用经修正的参数计算了马氏体相变开始温度Ms,提高了Ms点的预测精度,计算值与实验值的标准差为25.3℃.

关键词: 相变 , 热力学 , 超组元模型 , 相变平衡温度

高温退火后含He纳米晶钛膜中He相关缺陷的演化

李悦 , 邓爱红 , 刘莉 , 王康 , 谢莎

材料研究学报

利用x射线衍射(xRD)和慢正电子束分析(SPBA)技术研究高温退火后含He钛膜的微观结构和钛膜内He相关缺陷的演化.XRD分析表明,高温退火后Ti和Si在高温下发生反应形成稳定的多晶TiSi2化合物,He原子的掺入会影响TiSi2晶体的择优取向,而对TiSi2晶粒尺寸的影响较小.SPBA结果表明,室温下,钛膜内的缺陷浓度或尺寸会随着掺He浓度的增加而增大;高温退火后,当He浓度小于5％(原子分数,下同)时(除2％外),钛膜内的He相关缺陷浓度随着He浓度增加相应地增加.当He浓度增加到14％时,高温会使较高浓度的He原子、He-空位复合体以及小He泡迁移聚集形成一些尺寸较大He泡,而较大He泡周围与He相关的小尺寸缺陷的浓度则会发生相应地减少.

关键词: 金属材料 , 含He钛膜 , 直流磁控溅射 , He相关缺陷 , XRD , SPBA

直流磁控溅射沉积含He钛膜的研究

施立群 , 金钦华 , 刘超卓 , 徐世林 , 周筑颖

原子核物理评论 doi:10.3969/j.issn.1007-4627.2005.01.045

研究了用He/Ar混合溅射气体的直流磁控溅射制备钛膜中He的掺入现象.分析结果表明,大量的He原子(He/Ti原子比高达56%) 被均匀地引入到Ti膜中,He含量可由混合溅射气体的He分量精确控制.通过调节溅射参数,可实现样品中He的低损伤引入.研究还发现,溅射沉积的含氦Ti膜具有较高的He成泡剂量和高的固He能力,这可能是溅射沉积形成了纳米晶Ti膜所致.纳米晶Ti膜较粗晶材料具有很高浓度的He捕陷中心,使He泡密度增大而泡尺寸减小.随He引入量的增加,Ti膜的晶粒尺寸减小,He引起的晶体点阵参数和X射线衍射峰宽度增大,晶体的无序程度增加.

关键词: 氦 , 损伤 , 泡 , 钛膜 , 溅射沉积