微量Si、Mg元素对细化剂作用效果的影响

研究了6063合金中的微量Si、Mg元素对Al-Ti-C中间合金细化效果的影响,并探讨了其影响机理。结果表明：微量的Si、Mg元素均能促进Al-Ti-C中间合金对6063铝合金的细化作用,一般Si的含量在0.5％时,Al-Ti-C的细化效果最佳。在细化温度相同的情况下,Mg的促进作用更明显一些并且不存在“温度效应”。试验表明,当6063铝合金中同时存在微量的Si、Mg元素时,Al-Ti-C的细化效果会更加显著。     

Zr-Ti系贮氢合金表面改性研究

采用化学镀镍、镀钴、机械混合以及球磨几种方法对Zr-Ti系贮氢合金进行了表面改性。XRD结果表明，随着镀镍量的增加，合金越趋向微晶化；球磨时间越长，合金的衍射峰更加弥散化，充放电试验结果表明，当镀镍量为15％(质量分数，下同)时，贮氢合金在60mA.g^-1的电流密度下初始容量比未处理的合金高出130mAh．g^-1，经过6次～8次循环完全活化，最大放电容量可达400mAh．g^-1，随着镀镍量的增加，抗自放电能力增加；当镀钴量为5％时，贮氢合金在60mA．g^-1的电流密度下初始容量比未处理的合金高出40mAh．g^-1，经过7次～9次循环完全活化，最大放电容量可达390mAh．g^-1，但随着镀钴量的增加，初始容量上升较快，但放电容量在减少；而机械混合仅提高初始容量，对最大放电容量没有改善；球磨不仅改善贮氢合金的活化性能，并且其最大放电容量可达450mAh．g^-1。     

Electrochemical properties of CeMg_(11)Ni+x% Ni composites (x=0,50, 100 and 200) prepared by ball-milling

1　INTRODUCTIONMagnesium and magnesium based alloys arepromising hydrogen storage materials because oftheir absorbability of hydrogen in large quantities,low specific gravity, rich mineral resources, lowmaterial cost and so on. Nevertheless, their hy drides are too stable to be used at room tempera ture[1]. It seems impossible for application of crys talline Mg based alloys in nickel hydrogen batter ies.It is well known that amorphous alloys havemany advanta…     

钛合金精密铸造用陶瓷模壳研究

对适用于钛合金精密铸造用陶瓷模壳的制备工艺进行了系统的实验分析，表征了以过渡金属氧化物溶胶为粘结剂、稳定氧化锆为耐火材料的料浆的性能并讨论了相关参数的影响，对比研究了级配粉与均匀细粉制作的模壳的表面质量，结果表明，粗／细粉含量等级配参量和粉液比通过影响密度、粘度、滞流率以及涂层厚度等工艺参数而影响模壳的表面质量．在上述分析基础上确定了适用于本实验条件下钛合金精密铸造用陶瓷模壳的制备工艺参数。     

Microstructure Evolution of Intermetallics Produced by Laser Powder Deposition

NiAl intermetallic alloys are potential high temperaturestructural materials in aeronautical and astronauticalindustries[1].However,the poor ductility andtoughness at room temperature severely restrict theirengineering applications[2,3].It is important todevelop new technology to product intermetallicmaterials for the improvement of the comprehensiveproperties and the workability.Laser powder depositionhas been used to synthesize many new materials.Furthermore,if incorporated with rapid proto…     

提高铝合金上电镀镍层结合强度的研究

采用一步电镀镍和特殊铝合金表面预处理方法，获得高结合强度的电镀镍层。选用热震法测试铝合金基体与沉积镍层之间的结合强度，讨论了铝合金电沉积镍层厚度、温度、电流密度对结合强度的影响。试验结果表明，在采用低电流密度0．2－0．5A/dm^2，镀层厚度8－15μm，电镀液温度15－25℃条件下，电镀镍层与铝合金的结合强度最高。     

AA4343/AA3003铝合金薄板钎焊接头的显微组织特征

采用气氛保护钎焊工艺 ,对AA434 3/AA30 0 3铝合金复合板材料的钎焊接头组织特征 ,及其与焊接工艺的关系和对接头区显微硬度的影响进行了研究。实验结果表明 ,钎焊过渡区由单相α(Al)固溶体层和Si扩散层组成 ,它们的厚度随钎焊条件而发生变化。远离焊接区有一个α(Al)固溶体残余层 ,它的厚度保持 2 0 μm基本不变 ,与焊接参数和材料性质无关。讨论了钎焊接头特征组织的形成机理     

High-temperature precision forming of titanium blades

Based on the experimental study of superplastic deformation parameters, a technology was developed for producing near-net-shape compressor blade forgings for gas turbine units from Ti-6.2Al-2.5Mo-l.5Cr-0.2Si-0.5Fe. The mechanical properties of these blades are higher than those of blades produced by conventional methods, and the anisotropy coefficient is reduced. The improved properties of the blades can be attributed to the isotropy of mechanical properties resulting from the homogeneous fine-grained equiaxed structure produced throughout the blade volume.     

非晶Pd—Cu—Si合金的流变行为

在连续温条件下，测量了非晶Ｐｄ－Ｃｕ－Ｓｉ合金的应变速率和粘度随温度的变化曲线，在玻璃转变和晶化温区分别观测到伴随玻璃转变和晶化过程的粘度极小值，研究了升温速率对粘度极小值的影响，用结构转变的界晶模型解释了非晶Ｐｄ－Ｃｕ－Ｓｉ合金的粘滞行为。     

Sulfidation behavior of Fe-25Cr-20Ni-1.5Al2O3 in simulated coal combustion/gasification environments

The effect of minor addition of -Al₂O₃ dispersoids on the sulfidation behavior of Fe-25Cr-20Ni was investigated over a range of pO₂, 1.13×10^–20 to 1.18×10 ****^–22 atm. at constant pS₂=1.22×10^–8 atm. Fe-25Cr-20Ni and Fe-25Cr-20Ni 1.5 Al₂O₃ with and without preformed oxide scales were exposed to bioxidant gas mixtures H₂/H₂O/H₂S/Ar at 700° C. Both isothermal and cyclic exposures were included. Scales were characterized by a combination of several surface analytical tools. A remarkable improvement in sulfidation resistance is observed in Fe-25Cr-20Ni-1.5Al₂O₃ under the conditions investigated here. This is attributed to the ability of the alloy to form and maintain a predominantly Cr₂O₃ scale with reduced Fe-diffusion and content. Possible scientific reasons for such improvement are discussed. The base alloy, Fe-25Cr-20Ni, fails to develop and retain such a Cr₂O₃ scale and undergoes sulfidation within a few minutes of exposure. The scale breakdown process by sulfidation is explained qualitatively. Experimental evidence suggests that sulfur in the environment enhances Fe-diffusion and content in the scale.