Improving aging and creep resistance in a dilute Al-Sc alloy by microalloying with Si, Zr and Er
Improving aging and creep resistance in a dilute Al-Sc alloy by microalloying with Si, Zr and Er
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DOI：
10.1016/j.actamat.2013.10.008
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发表时间：
2014-01-15
期刊：
影响因子：
9.4
通讯作者：
Seidman, D. N.
中科院分区：
文献类型：
--
作者：
Vo, N. Q.;Dunand, D. C.;Seidman, D. N.
研究了含有各种微合金添加剂的 Al-0.06Sc at.% 合金中的纳米级析出物，目的是利用显微硬度、电导率和原子探针断层扫描测量来开发用于高温应用的经济高效的铝合金。用 0.005 at.% Er 代替更昂贵的 Sc 可以保持较高的环境温度强度，并显着提高高温抗蠕变性，正如从 α-Al(fcc) 基体和相干 L1(2) 有序 Al-3(Sc,Zr,Er) 沉淀物之间晶格参数失配的增加所预期的那样。低至 0.02 at.% 的慢速扩散剂 Zr 浓度足以通过形成封装沉淀物的富 Zr 外壳，在 400 C（同系温度 0.72）下提供长达 66 天的抗粗化性。最后，添加 0.05 at.% Si 通过增加析出物的数密度来增强环境温度强度，同时减少均匀化和峰值时效热处理时间，这是由 Si 原子加速 Er 和 Sc 扩散动力学引起的。由于商业纯铝中含有硅，含硅合金也具有成本效益。但是，Si的添加会降低析出物粗化阻力：然而，这种影响的大小由Si浓度决定。 (C) 2013 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
Nanosized precipitates in an Al-0.06Sc at.% alloy containing various microalloying additions were studied, with the goal of developing cost-effective aluminum alloys for high-temperature applications, using micro-hardness, electrical conductivity and atom-probe tomography measurements. Substituting 0.005 at.% Er for the more expensive Sc maintains high ambient-temperature strength, and dramatically improves the high-temperature creep resistance, as anticipated from the increase in lattice parameter mismatch between the alpha-Al(fcc) matrix and the coherent L1(2)-ordered Al-3(Sc,Zr,Er) precipitates. A concentration of the slow-diffuser Zr as low as 0.02 at.% is sufficient to provide coarsening resistance at 400 C (an homologous temperature of 0.72) for up to 66 days by forming a Zr-enriched outer shell encapsulating the precipitates. Finally, adding 0.05 at.% Si enhances ambient-temperature strength by increasing the number density of precipitates, while decreasing the homogenization and peak-aging heat-treatment times, which is caused by the Si atoms accelerating the Er and Sc diffusion kinetics. Si-containing alloys are also cost effective, owing to the existence of Si in commercial purity Al. But addition of Si reduces the precipitate coarsening resistance: the magnitude of this effect is, however, determined by the Si concentration. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.