Mechano-Synthesis of Niobium-Aluminum Superconductors for High Field Applications
Mechano-Synthesis of Niobium-Aluminum Superconductors for High Field Applications
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DOI：
10.4028/www.scientific.net/msf.269-272.1043
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发表时间：
1998-01
期刊：
影响因子：
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通讯作者：
A. Całka;D. Wexler;J. Zhou;M. Sumption;E. Collings
中科院分区：
文献类型：
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作者：
A. Całka;D. Wexler;J. Zhou;M. Sumption;E. Collings
在目前的调查中，磁力机械合成，使用一种新的研磨技术，适用于混合物的Al和Nb粉末在氩气中研磨在不同的研磨条件下。使用X射线衍射法，热分析，反射光和电子显微镜监测结构的发展。使用球冲击方法研磨的粉末，并且在剪切模式下，在球上具有强磁拉力，观察到由于冷焊而团聚。然而，在剪切下研磨的粉末，与中间拉力显示连续的结构演变，与Nb-Al固溶体发生在30小时内的研磨。随着球磨时间的增加，Nb 3Al的晶格常数迅速减小，在球磨250 h左右达到极限值0.5185nm。差热分析结果表明，Nb 3Al形成的激活能为377 kJ/mol，远高于晶粒长大的激活能，但接近于纯元素Al和Nb的自扩散激活能。
In the present investigations, magneto-mechano synthesis, using a novel milling technique, was applied to mixtures of Al and Nb powders milled in Ar under different milling conditions. Structural development was monitoring using x-ray diffractometry, thermal analysis, and reflected light and electron microscopy. Powders milled using the ball impact method, and under shearing mode with a strong magnetic pulling force on the balls were observed to agglomerate due to cold welding. However, powders milled under shearing, with intermediate pulling force displayed continuous structural evolution, with Nb-Al solid solution occurring within 30 h of milling. With increased milling time there was a rapid decrease in Nb 3 Al lattice parameter, which reached a limiting value of 0.5185nm at around 250h milling. The DTA traces indicated an activation energy (Ea) of 377kJ/mol) for formation of Nb 3 Al, much higher than that reported for grain growth only, but close to that for the self-diffusion of pure elements, Al and Nb.