J. Feng
,
W.D. Huang
,
X. Lin
,
T. Li
,
Y.F. Xue and Y.H. Zhou(State Key Lab. of Solidilication Processing
,
Northwestern Polytechnical University
,
Xi'an 710072
,
China)
金属学报(英文版)
In order to investigate the response of cellular spacing to the variation of growth velocity under near-rapid directional solidification condition, Al-0.53wt%Zn alloy is directionally solidified with Bridgman apparatus. The results show that at the given temperature gradient the obtained microstrvctures are all cells and there exists a wide distribution range of cellular spacing. The maximum, λmax, minimum, λmin, and average cellular spacing, λ, as functions of growth rate, V, can be given by λmax=948.51V-0.4961, λmin= 661.16V-0.5015 and λ=412.41V-0.5049, respectively. The experimental results are compared with that predicted by KGT model, and a good agreement is found. Moreover,it is found that the average cellular spacing is also remarkably history-dependent.
关键词:
Al-Zn alloy
,
null
,
null
,
null
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
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
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
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
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
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
HUANG Huimin CHEN Xinmin Central South University of Technology
,
Changsha
,
China HUANG Huimin Associate Professor
,
Department of Chemistry
,
Central South University of Technology
,
Changsha
,
China
金属学报(英文版)
The nature of the oxygen contained in β-W was investigated with DSC,X-ray analysis on quenched samples and Auger spectroscope.It was shown that the oxygen contained in nonpyrophoric β-W consists of the reversibly chemisorbed oxygen and the interstitial oxygen which could form an interstitial solid solution with β-W.It seems better to consider β-W to be a metastable phase of tungsten with the interstitial oxygen as stabilizer.
关键词:
tungsten
,
null
,
null
,
null
