P. Fernandez G. Gonzalez I. Alfonso I.A. Figueroa
材料科学技术（英文）
Two ternary Al-2.2Zn-0.95Mg and Al-5.5Zn-2.1Mg (in wt pct) alloys, with Zn:Mg ratios close to 2.5 were produced by conventional ingot casting metallurgy. The ingots were solution heat treated at 500°C for 0.5 h and aged at 180°C for times between 0.5 and 80 h. The structural characterization was carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Vickers microhardness measurements (HV). The study was focused on the investigation of the precipitates formation and the relationship between hardness and lattice parameter for α-Al. The results showed that there was an inverse correlation for all the experimental conditions, and the aged peaks coincided with lattice parameter minima. Significant precipitates formation only occurred for the alloy containing 5.5 wt pct Zn and 2.1 wt pct Mg, provoking an important strengthening and variations in the lattice parameter, however, this was not observed for the alloy containing 2.2 wt pct Zn and 0.95 wt pct Mg. A plausible explanation of the increment of hardness values could be the presence of a well distributed μ phase (MgZn2). At initial stages of the precipitation process, μ' was the most abundant precipitate while the phase τ was observed at overaged conditions. These results showed that the aging response of the conventionally cast Al-Zn-Mg alloys could be obtained using the lattice parameter of the α-Al matrix, even for alloy systems with low precipitates formation.
关键词:
Aluminum alloy
,
X-ray diffraction
,
Precipitation
,
Lattice parameter
,
Hardness
王宝顺林奔张麦仓董建新
金属学报
doi:10.3724/SP.J.1037.2010.00511
研究了G3镍基耐蚀合金管材玻璃润滑热挤压工艺中润滑膜的成膜行为, 建立了润滑膜厚度的理论计算模型. 同时, 针对6000 t卧式挤压机, 结合G3合金热挤压工艺有限元模拟分析, 对热挤压工艺参数和玻璃润滑剂黏度进行了系统的研究. 结果表明, 可以通过玻璃润滑膜厚度及完成一次热挤压所需玻璃垫厚度的理论计算公式优化G3合金管材热挤压工艺参数, 并进一步获得了玻璃润滑剂黏度性质须满足: 玻璃粉的软化温度大约为720 ℃;在720-800 ℃, 玻璃黏温系数在-0.05 ℃-1和-0.04 ℃-1之间;热变形温度1100-1200 ℃区间的黏度为25-200 Pa?s.
关键词:
镍基合金
,
hot extrusion
,
glass lubricant
崔建国
,
马莒生
,
傅永辉
,
李年
,
孙军
,
何家文
金属学报
考察了爆炸复合双层金属板LYl2/20g中界面两侧材料弹塑性失配对面裂纹疲劳扩展行为的影响.结果表明,当裂纹由弹性模量、屈服强度高的一侧向低的一侧扩展时,实际驱动力大于外加名义值;当裂纹由弹性模量、屈服强度低的一侧向高的一侧扩展时,实际驱动力小于外加名义值,从而造成裂纹扩展的加速或止裂,其影响离界面越近效果越显著,但弹性模量失配在裂纹开始扩展直至界面的过程中都起作用,而强度失配只在裂尖距界面一定距离范围内(Rp)才起作用.
关键词:
LYl2/20g爆炸复合板
,
null
崔建国
,
马莒生
,
傅永辉
,
李年
,
孙军
,
何家文
金属学报
doi:10.3321/j.issn:0412-1961.2001.12.007
考察了爆炸复合双层金属板LYl2/20g中界面两侧材料弹塑性失配对面裂纹疲劳扩展行为的影响.结果表明,当裂纹由弹性模量、屈服强度高的一侧向低的一侧扩展时,实际驱动力大于外加名义值;当裂纹由弹性模量、屈服强度低的一侧向高的一侧扩展时,实际驱动力小于外加名义值,从而造成裂纹扩展的加速或止裂,其影响离界面越近效果越显著,但弹性模量失配在裂纹开始扩展直至界面的过程中都起作用,而强度失配只在裂尖距界面一定距离范围内(Rp)才起作用.
关键词:
LYl2/20g爆炸复合板
,
疲劳裂纹
,
弹塑性失配
张国俊
,
许赵辉
,
刘忠洲
膜科学与技术
doi:10.3969/j.issn.1007-8924.2002.02.010
采用截留分子量(MWCO)1万的卷式超滤膜和截留分子量(MWCO)6 000的中空纤维超滤膜,去除I+G粗品液中影响I+G产品透光的色素、大分子蛋白及可溶性胶体蛋白,不需加碳、压滤等工序,产品透光合格率达100%,产品透光的合格稳定性较现有生产工艺大大提高,该工艺不仅可以省去加碳压滤等工序,而且可以保证产品一次性达到合格产品.
关键词:
肌苷酸
,
鸟苷酸
,
超滤
,
透光
Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films
Chromium nitride (CrN) films were deposited on Si wafers by arc ion plating (AIP) at various negative bias voltages and several groups of N-2/Ar gas flux ratios and chamber gas pressures. The authors systematically investigated the influence of negative bias voltage on the synthesis, composition, microstructure, and properties of the AIP CrN films. In this part (Part I), the investigations were mainly focused on the macroparticle distributions and film-growth characteristics. The results showed that macroparticle densities on the film surfaces decreased greatly by applying negative bias voltage, which can be affected by partial pressure of N-2 and Ar gases. From the statistical analysis of the experimental results, they proposed a new hybrid mechanism of ion bombardment and electrical repulsion. Also, the growth of the AIP CrN films was greatly altered by applying negative bias voltage. By increasing the bias voltage, the film surfaces became much smoother and the films evolved from apparent columnar microstructures to an equiaxed microstructure. The impinging high-energy Cr ions accelerated by negative bias voltages were deemed the inherent reason for the evolution of growth characteristics. (c) 2008 American Vacuum Society.
关键词:
chromium nitride films;hybrid coating system;structure zone model;si-n coatings;mechanical-properties;tin films;thin-films;pulse bias;vacuum;evaporation
马忠龙
,
杨琤
,
李振花
,
许根慧
催化学报
在常压及650℃下,考察了CaO,SrO,La2O3,ZnO,TiO2,CeO2和MnO2膜上外加电流为16～90 mA时传递物系的甲烷氧化偶联反应结果.结果发现,在n型和p型半导体催化膜上.CC2,C2H4和C2H6的生成速率都随泵氧量的增加而增大,而C2烃选择性随泵氧量的增加而下降,但p型半导体膜上的C2烃选择性比n型半导体膜上的要高;p型半导体膜上C2烃选择性与其电导率大小顺序相一致.增强因子的分析结果表明,在传递体系中,p型半导体膜上增强因子的值小于1,但随泵氧量的增加而存在极大值.在CaO膜上,传递体系比开路体系的C2烃选择性高,且随泵氧量的增加而下降.
关键词:
泵氧
,
半导体催化膜
,
甲烷
,
氧化偶联
,
增强因子
,
传递体系
骆良顺张宇民苏彦庆王新郭景杰傅恒志
金属学报
doi:10.3724/SP.J.1037.2010.00485
利用电阻加热和感应加热Bridgman定向凝固系统对非小平面包晶系模型合金Fe-Ni合金进行系统的定向凝固实验研究, 探索2种常规定向凝固条件下对流对包晶合金定向凝固过程中带状组织和宏观偏析的影响规律.发现在高G/V定向凝固过程中, 对流使包晶合金定向凝固过程中轴向和径向形成严重的宏观偏析, 从而使组织演化异常复杂且难以达到稳态.轴向宏观偏析体现在有限长试样从定向凝固开始至凝固结束都将发生初生相向包晶相的转变过程, 转变过程受合金成分和对流强度影响.径向宏观偏析体现在试样心部贫溶质易形成初生相, 边缘富集溶质易形成包晶相, 在径向上也存在初生相向包晶相的转变过程.
关键词:
包晶合金
,
directional solidification
,
convection
,
segregation
,
banding structure
