材料期刊网

Effects of Boron Addition on Grain Refinement in TiAl-based Alloys

W.D. Wang

材料科学技术（英文）

Solid state phase transformation characteristics of the body centred β(Ti) into the hexagonal closed packed α(Ti) in Ti₄₅Al₈Nb-(0, 0.3, 0.5 and 0.8 at. pct) B alloys were investigated by heat treatment to clarify γ/α₂ lamellar microstructure refinement induced by B addition. Experimental results confirmed two kinds of boron-reduced grain refinement mechanisms through refining either β phase thenα phase (β-refinement) or α phase directly (α-refinement) to refine lamellar microstructure at room temperature; however, the role of α-refinement dominated the as-cast lamellar microstructure refinement over β-refinement in Ti₄₅Al₈Nb_xB alloy. It was also found that during the α-refinement the convoluted flake- and plate-like borides along β grain boundaries assisted nucleation of α phase, and the particle-like borides near β grain boundaries impeded α phase growth.

关键词: Titanium aluminides , Phase transformation , Microstructure

Ni-W(D)刷镀层再强化机理的研究

徐江 , 揭晓华 , 段桂生

电镀与精饰 doi:10.3969/j.issn.1001-3849.1999.03.010

对Ni-W(D)刷镀层进行热处理,测量了热处理前后镀层硬度的变化,并利用X-射线衍射,对刷镀Ni-W(D)镀层再强化机理作了研究.在摩擦磨损实验中,利用了电子探针,对磨损前后镀层成分进行了分析,探讨了造成成分变化的原因,主要是W朝磨损区偏聚.

关键词: Ni-W(D)刷镀层 , 再强化 , 偏聚

First-principle investigation of 3d transition metal elements in gamma '-Co(3)(Al, W)

Journal of Applied Physics

The alloying effect of 3d transition metal elements on the lattice constants and their site preferences in gamma'-Co(3)(Al, W) are systematically studied based on a supercell model. The lattice constant of the gamma' phase is modified by the addition of 3d transition metal elements, and it increases in the order of Fe < Ni < Mn < Cr < V < Ti. Four types of site preference are identified for these 3d elements in gamma' phase by analyzing the binding energy and the impurity formation energy. Ni, Fe, V, and Ti are recognized to stabilize the gamma' phase. Their distinct alloying effect is further revealed by investigating the impurity-induced charge density difference and the partial density of states. These results are in agreement with the experimental data ever reported. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3319650]

关键词: augmented-wave method;co-base superalloy;electronic-structure;site;preference;ni3al;phase;temperature;stability;magnetism;alloys

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

摩擦电刷镀Ni-W-D合金镀液改良及镀层性能研究

丁红珍 , 李尚周

电镀与涂饰 doi:10.3969/j.issn.1004-227X.2005.08.003

给出了改良的Ni-W-D合金镀液配方,并介绍了镀液性能参数.采用自制的摩擦电刷镀装置进行了工艺实验.测定了镀层性能并采用X-射线衍射仪测试了镀层的相组成.分别用扫描电镜和能谱仪对镀层形貌及组成进行了观察与分析.结果表明:改良后的镀液得到的镀层有良好的结合力、较高的硬度和耐磨性,硬度平均值在620 HV以上;且该镀层为单相镍面心立方固溶体,表面和横截面无明显裂纹,其中Ni,W,Co,Fe含量分别为84.05%,4.39%,7.66%,3.89%.

关键词: 摩擦电刷镀 , Ni-W-D合金镀液 , 结合力 , 硬度 , 耐磨性

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

Mg2B2O5w/AZ91D镁基复合材料的界面结构及其形成机理

陈善华 , 何晓明 , 金培鹏 ,

材料热处理学报

采用X射线衍射仪、X射线光电子能谱仪、扫描电子显微镜和透射电子显微镜对萃取Mg2B2O5w的物相、表面元素化学状态变化及Mg2B2O5w/AZ91D复合材料界面反应产物进行了研究.结果表明:Mg2B2O5w/AZ91D界面处存在厚度不均匀的MgO和MgB2相界面层;MgO的形成主要与复合材料制备过程中晶须表面上的吸附氧有关,而界面产物MgB2则应来源于Mg2B2O5w分解产物B2O3与基体中Mg的反应;Mg2B2O5w、MgO和MgB2之间通常没有确定的晶体学位相关系,但在特定Mg2B2O5w表面观察到(202)Mg2B2O5w//(002)MgO,[010]Mg2B2O5//[110]MgO和(002)MgO//(0001)MgB2,[110]MgO//[2110]MgB2取向关系.

关键词: Mg2B2O5w , 镁基复合材料 , 界面 , 形成机理

AZ91D镁合金化学镀Ni-P及Ni-W-P镀层的结构与耐蚀性

李端阳 , 沈波 , 任玉平 , 裴文利 , 杨中东 , 王继杰 , 秦高梧

中国腐蚀与防护学报

在AZ91D镁合金上直接化学镀Ni-P和Ni-W-P镀层，并利用扫描电子显微镜、X射线衍射仪及电化学工作站研究后续热处理对化学镀层组织形貌、相组成及其耐蚀性的影响。结果表明，制备的Ni-P镀层为非晶态，而Ni-W-P镀层为纳米晶结构，两者在3.5%NaCl水溶液中的耐蚀性相当。热处理可以明显提高Ni-W-P镀层的耐蚀能力，但却稍微弱化Ni-P镀层的耐蚀能力，热处理后的Ni-W-P层自腐蚀电位相对于未处理的化学镀Ni-W-P或Ni-P层提高了约150 mV。

关键词: AZ91D镁合金 , Ni-P coating , Ni-W-P coating , corrosion resistance

AZ91D镁合金化学镀Ni-P/Ni-W-P双层镀层研究

李光玉 , 程仲基 , 牛丽媛 , 连建设

材料科学与工艺

为了提高镁合金的耐磨耐蚀性,研究了一种镁合金直接化学镀Ni-P/Ni-W-P双层镀层的方法.采用扫描电镜(SEM)和X-射线衍分析射仪(XRD)分析了镀层的微观结构.对镀层进行了极化曲线分析,并进行了盐酸腐蚀试验和结合力试验.结果表明,该复合镀层组织致密无孔,具有较高的显微硬度和高耐蚀性.镀层硬度可达622 HKV,试样在10%的HCl溶液中可保持近3 h不腐蚀基体,对镁合金起到很好的保护作用.

关键词: 镁合金 , 化学镀 , Ni-W-P , AZ91D , 耐蚀性

热处理对Mg2B2O5w/AZ91D复合材料组织及性能的影响

金培鹏 , 丁雨田 , 史训兵 , 许广济 , 刘孝根

材料热处理学报

研究了固溶处理和时效处理的Mg2B2o5w/AZ91D镁基复合材料组织与显微硬度之间的关系.结果表明:经过415℃固溶处理后,共晶相的分解使复合材料的硬度明显下降.时效处理使得复合材料的硬度逐渐增加并在时效处理200℃×16h后出现时效峰值201HV,然而随着时效时间的进一步增加,显微硬度降低.经固溶处理415℃×24h,基体中β-Mg17Al12相基本溶解,形成过饱和固溶体,接着时效处理8h,β-Mg177Al12相以弥散形式析出,从而使得复合材料的显微硬度提高30%;而固溶处理415℃×24h,接着200℃时效处理24h后,析出相在形貌上由连续细小析出相向非连续粗大析出相过渡,这使得复合材料的显微硬度下降到183HV.

关键词: 镁基复合材料 , 热处理 , 固溶 , 时效