材料期刊网

STABILIZATION OF MARTENSITE AND PARENT PHASE ORDERING IN A Cu-Zn-Al ALLOY

CHEN Shuchuan XU Zuyao (T.Y.Hsu) YANG Fan Shanghai Jiaotong University , Shanghai , ChinaZHANG Jihua Shanghai Institute of Metallurgy.Academia Sinica , Shanghai.China

金属学报(英文版)

The reverse transformation has never occurred in a quenched and aged specimen upon heating from room temperature to 320℃ at which the martensite disappears thoroughly.Both B2 9R and DO_318R coexist in step-quenched and short-time isothermally treated specimen. As prolonging the isothermal holding,the B29R disappears and DO_318R intensifies. B29R occurs only in specimen quenched and up-quenched immediately to 100—150℃. Rapid quenching from high temperatures will depress the B2→DO_3 ordering but not the A2 →B2 one.A plenty enough concentration of vacancy is a necessary condition of occurrence of B2→DO_3 ordering.The possible mechanism for the stabilization of martensite in a Cu-Zn-Al alloy was also discussed.

关键词: stabilization of martensite , null , null

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

基于(火积)耗散率最小的T-Y形肋片构形优化

冯辉君 , 陈林根 , 谢志辉 , 孙丰瑞

工程热物理学报

基于构形理论,以导热和对流换热总(火积)耗散率最小为优化目标,对T-Y形肋片进行构形优化,得到同时考虑导热和对流换热(火积)耗散性能的T-Y形肋片最优构形.结果表明:存在最佳单元级直肋和中部空腔高度和长度比使得T-Y形肋片无量纲当量热阻取得二次最小值.增大肋片高度和长度比和肋片占比有助于提高T-Y形肋片整体传热性能.T-Y形肋片与T形肋片相比,T-Y形肋片二次最小无量纲当量热阻降低32.33％,此时T-Y形肋片温度梯度场更均匀,整体传热性能得到明显提高.

关键词: 构形理论 , (火积)耗散率最小 , T-Y形肋片 , 对流换热 , 广义热力学优化

Huazhong University of Science and Technology(H.U.S.T)

材料科学技术（英文）

关键词:

Chen系统的状态变量周期性反馈控制

李开明 , 李亚洲 , 冯维贵 , 林长

量子电子学报 doi:10.3969/j.issn.1007-5461.2007.05.014

采用非线性反馈控制,用附加了带参数的正弦项对Chen系统进行了有效的控制.随着参数k的逐渐增大,系统的动力学行为呈现出一系列的变化.数值研究结果表明:随控制参数的增大,驱动信号的强度渐大,混沌系统由混沌运动到周期轨道,最终到一相点.

关键词: 混沌 , Chen系统 , 不动点 , Lyapunov指数 , 反馈控制

The crossover from parallel shift to fan-shape broadening of the superconducting transition of La(1.44)Nd(0.4)Sr(0.16)CuO(4) films in magnetic fields

Superconductor Science & Technology

In this paper we report the transport properties of c-axis-oriented superconducting La(1.44)Nd(0.4)Sr(0.16)CuO(4) films on LaSrAlO(4) substrates with different thicknesses in various magnetic fields parallel and perpendicular to the c axis of the films. It is found that with decreasing film thickness there is a crossover from the parallel shift to fan-shape broadening in the resistive transitions. Moreover, for both field configurations, the flux pinning potential U(0)(H) of the film shifts upward with an order of magnitude with increasing in-plane compressive strain. These results indicate that the compressive epitaxial strain and strain-induced destabilization of the static charge stripes are important aspects for the promotion of superconducting transition temperature as well as the flux pinning potential.

关键词: high-temperature superconductors;crystal thin-films;flux motion;la2-xsrxcuo4;strain;insulator;dependence;behavior

AA6061-T6铝合金表面纳米Y2 O3改性硅烷膜的耐蚀性

张明明 , 李文超 , 张圣麟

腐蚀与防护

采用动电位极化曲线，电化学阻抗谱（EIS）和中性盐雾试验（NSS）研究了溶液中加入不同含量纳米Y2 O3对铝合金AA6061-T6表面硅烷膜耐蚀性的影响，采用扫描电镜（SEM）对其形貌进行了观察。结果表明，在1，2-双-三乙氧基硅烷（BTSE）溶液中加入少量纳米Y2 O3可提高硅烷膜在3．5％ NaCl溶液中的耐蚀性。硅烷膜对铝合金的保护只起到物理屏障作用。纳米Y2 O3抑制了电化学腐蚀过程中阴极还原反应的发生，但不影响电极反应的动力特征。SEM表明在BTSE硅烷溶液中添加10～20 mg/L的纳米Y2 O3后，硅烷膜表面变得平滑致密。

关键词: 硅烷膜 , 纳米Y2 O3 , 耐蚀性能 , 铝合金

纳米Y2O3预处理对T91钢抗高温水蒸汽氧化的影响

刘光明 , 张都清 , 任善平

表面技术 doi:10.16490/j.cnki.issn.1001-3660.2015.12.017

目的 研究纳米Y2 O3 预处理对T91钢抗水蒸汽氧化性能的影响,分析稀土元素作用的机理及长期氧化后的失效机制. 方法 采用将Y2 O3、铝粉、粘结剂制备成料浆涂覆于T91钢表面,并在720 ℃水蒸汽中预处理48 h. 预处理样品和空白样品同时置于在700 ℃高温水蒸汽中氧化,获取循环氧化动力学曲线并进行对比,检验预处理对提高材料抗高温水蒸汽腐蚀的效果. 对氧化的样品采用XRD、SEM/EDS对氧化物结构、形貌、成分进行分析. 结果 预处理后在样品表面形成了含Y2 O3 的富铬氧化物薄膜. 在高温水蒸汽环境的氧化过程中,试样处理600 h时,质量增加轻微,仅为0. 152 g/cm2. 但在600 h后质量增加明显,预处理膜层逐渐退化,表面出现Fe2 O3 突出物. 空白样在腐蚀初期即明显增加,氧化70 h后,质量增加达12. 17 mg/cm2 ,氧化过程中可见氧化产物的剥落,氧化膜附着力差. 结论 纳米Y2 O3预处理可提高T91钢抗水蒸汽氧化性能,但随着氧化时间延长,富铬氧化膜将逐渐退化.

关键词: 纳米Y2O3 , T91钢 , 预处理 , 水蒸汽 , 高温氧化 , 富铬氧化膜

Mg-9Gd-4Y-0.6Zr合金挤压T5态的高温组织与力学性能

肖阳 , 张新明 , 陈健美 , 蒋浩

中国有色金属学报

研究了Mg-9Gd-4Y-0.6Zr合金挤压T5态在250～400℃之间的高温组织与力学性能. 结果表明:该合金具有非常优异的高温力学性能,其力学性能明显优于WE54;该合金在250、300、350和400℃时的抗拉伸强度分别为348、262、150和62MPa;该合金在400℃拉伸时还具有粗晶超塑性,晶界上有再结晶的细晶,晶内有大量孪晶同时共存.

关键词: Mg-Gd-Y-Zr合金 , 耐热镁合金 , 高温力学性能 , T5态 , 粗晶超塑性

Improving glass-forming ability of Mg-Cu-Y via substitutional alloying: Effects of Ag versus Ni

Journal of Materials Research

Based on the best bulk metallic glass (BMG) forming alloy in the Mg-Cu-Y ternary system, we introduced Ag (or Ni) to partially substitute for Cu to improve the glass-forming ability (GFA). The objective of this paper is twofold. First, we illustrate in detail a recently developed search strategy, which was proposed but only briefly outlined in our previous publication [H. Ma, L.L. Shi, J. Xu, Y. Li, and E. Ma: Discovering inch-diameter metallic glasses in three-dimensional composition space. Appl. Phys. Lett. 87, 181915 (2005)]. The protocol to navigate in three-dimensional composition space to land large BMGs is spelled out step-by-step using the pseudo-ternary Mg-(Cu,Ag)-Y as the model system. Second, our ability to locate the best BMG former in the composition tetrahedron allows us to systematically examine, and conclude on, the effects of a given alloying element. The large improvement in glass-forming ability in the Mg-(Cu,Ag)-Y system relative to the based ternary will be contrasted with the reduced glass-forming ability in the Mg-(Cu,Ni)-Y pseudo ternary system. It is demonstrated that the improvement of glass-forming ability requires judicious choice of substitutional alloying elements and concentrations, rather than simple additions of multiple elements assuming the "confusion principle."

关键词: bulk metallic-glass;shaped copper mold;amorphous-alloys;thermal-stability;ternary-system;casting method;p system;diameter;zr;mm