材料期刊网

THERMODYNAMIC CRITERION OF SPINODAL DECOMPOSITION IN TERNARY SYSTEMS

JIANG Bohong ZHANG Meihua WEI Qing XU Zuyao(T.Y.Hsu) Shanghai Jiaotong University , Shanghai , China

金属学报(英文版)

By expanding the Gibbs free energy of a ternary system into a Taylor series with respect to the composition,a thermodynamic criterion of spinodal decomposition is conducted as G_(xx)(δx)2+2G_(xx)δxδy+G_(yy)(δy)~2<0,from which,various conditions of spinodal decomposition are discussed.When G_(xx)<0 G_(xy)~2-G_(xx)G_(yy)<0,it is called unstable decomposition unrestricted by the direction of composition fluctuation;when G_(xx)<0,G_(xy)~2-G_(xx)G_(yy)>0,or G_(xx)>0, G_(xy)~2-G_(xx)G_(yy)>0,as well as G_(xx)=0,are all considered as unstable decomposition restricted by the direction of composition fluctuation δx and δy.The phenomenon of turning round in composition during spinodal decomposition is attempted to be explained from above point of view.The computer calculated ranges of unstable decomposition according to the criterion of spinodal decomposition on Cu-Ni-Fe ternary system is consistent with the experimental re- sults obtained from literatures.

关键词: spinodal decomposition , null , null

Ion sputter erosion in metallic glass-A response to "Comment on: Homogeneity of Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass" by L-Y. Chen, Y-W. Zeng, Q-P. Cao, B-J. Park, Y-M. Chen, K. Hono, U. Vainio, Z-L. Zhang, U. Kaiser, X-D. Wang, and J-Z Jiang J. Mater. Res. 24, 3116 (2009)

Journal of Materials Research

The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.

关键词: room-temperature

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:

Jian ZHANG/Langhong Lou

材料科学技术（英文）

关键词:

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