Al13Co4

  • 文章类型: Journal Article
    本工作评估了Co含量对各种成分(2-32wt%Co)的Al-Co合金的微观结构和腐蚀性能的影响,通过焊剂辅助搅拌铸造制造。对热处理效果的初步调查(600°C,长达72h)还对Al-20wt%Co和Al-32wt%Co的微观结构和腐蚀行为进行了研究。Al-(2-10)wt%Co合金由均匀分散在Al基体中的针状Al9Co2颗粒组成。Al-20wt%Co和Al-32wt%Co合金还包含包裹在Al9Co2楔形物中的Al13Co4叶片。Al-20wt%Co和Al-32wt%Co的热处理导致Al13Co4的体积分数显着降低,硬度降低。具有高Co含量(10-32wt%Co)的Al-Co合金在3.5wt%NaCl中表现出对局部腐蚀的更大抵抗力,但与(0-5wt%的Co)合金相比,对一般腐蚀的抵抗力较低。热处理导致Al-Co合金的耐腐蚀性略有增加。分析了所生产合金的微观结构,并将其与腐蚀性能相关联。最后,制定了腐蚀机理。
    The present work evaluates the effect of Co content on the microstructure and corrosion performance of Al-Co alloys of various compositions (2-32 wt% Co), fabricated by flux-assisted stir casting. A preliminary investigation on the effect of heat treatment (600 °C, up to 72 h) on the microstructure and corrosion behavior of Al-20 wt% Co and Al-32 wt% Co was also conducted. The Al- (2-10) wt% Co alloys were composed of acicular Al9Co2 particles uniformly dispersed in an Al matrix. The Al-20 wt% Co and Al-32 wt% Co alloys additionally contained Al13Co4 blades enveloped in Al9Co2 wedges. Heat treatment of Al-20 wt% Co and Al-32 wt% Co led to a significant reduction in the volume fraction of Al13Co4 and a decrease in hardness. Al-Co alloys with high Co content (10-32 wt% Co) exhibited greater resistance to localized corrosion in 3.5 wt% NaCl, but lower resistance to general corrosion compared to the (0-5 wt% Co) alloys. Heat treatment led to a slight increase in the corrosion resistance of the Al-Co alloys. The microstructure of the produced alloys was analyzed and correlated with the corrosion performance. Finally, corrosion mechanisms were formulated.
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  • 文章类型: Journal Article
    复杂的金属间化合物,例如过渡金属(TM)铝化物是昂贵的Pd基催化剂的有希望的替代品,特别是用于炔烃或链二烯的半氢化。这里,我们比较了邻Al13Co4(100)的气相丁二烯加氢性能,m-Al13Fe4(010)和m-Al13Ru4(010)表面,其整体终止结构模型表现出类似的簇状排列。此外,表面取向的影响通过o-Al13Co4(100)和o-Al13Co4(010)之间的比较来评估。因此,确定以下室温活性顺序:Al13Co4(100) Complex intermetallic compounds such as transition metal (TM) aluminides are promising alternatives to expensive Pd-based catalysts, in particular for the semi-hydrogenation of alkynes or alkadienes. Here, we compare the gas-phase butadiene hydrogenation performances of o-Al13Co4(100), m-Al13Fe4(010) and m-Al13Ru4(010) surfaces, whose bulk terminated structural models exhibit similar cluster-like arrangements. Moreover, the effect of the surface orientation is assessed through a comparison between o-Al13Co4(100) and o-Al13Co4(010). As a result, the following room-temperature activity order is determined: Al13Co4(100) < Al13Co4(010) < Al13Ru4(010) < Al13Fe4(010). Moreover, Al13Co4(010) is found to be the most active surface at 110°C, and even more selective to butene (100%) than previously investigated Al13Fe4(010). DFT calculations show that the activity and selectivity results can be rationalized through the determination of butadiene and butene adsorption energies; in contrast, hydrogen adsorption energies do not scale with the catalytic activities. Moreover, the calculation of projected densities of states provides an insight into the Al13TM4 surface electronic structure. Isolating the TM active centers within the Al matrix induces a narrowing of the TM d-band, which leads to the high catalytic performances of Al13TM4 compounds.
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