Microstructure and oxidation behavior of new refractory high entropy alloys
Microstructure and oxidation behavior of new refractory high entropy alloys
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DOI：
10.1016/j.jallcom.2013.08.102
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发表时间：
2014-01-15
影响因子：
6.2
通讯作者：
Zhang, A. L.
中科院分区：
文献类型：
--
作者：
Liu, C. M.;Wang, H. M.;Zhang, A. L.
高熵合金（High-entropy alloys，HEAs）是指由至少五种等摩尔或接近等摩尔的主元素组成的合金，在凝固过程中有利于形成简单的固溶体。近年来的研究表明，耐高温HEAs在高温结构材料方面具有很好的应用前景。然而，它们的氧化行为却很少受到关注。本研究通过添加Cr、Al和Si元素来提高材料的抗氧化性能，设计并合成了四种新型的耐高温HEAs：NbCrMoTiAl 0. 5（H-Ti）、NbCrMoVAl 0. 5（H-V）、NbCrMoTiVAl 0. 5（H-TiV）和NbCrMoTiVAl 0. 5Si 0. 3（H-TiVSi 0.3）。研究了它们的显微结构和氧化行为。正如预期的那样，由于高混合熵效应，这些难熔HEAs主要由简单的体心立方（BCC）难熔金属固溶体（RMss）组成。通过对凝固过程的研究和热力学分析，解释了其微观组织的形成机理。对于所有耐火HEAs，在1300摄氏度下的氧化动力学遵循线性行为。添加Ti和Si可显著提高HEAs的抗氧化性，而添加V则会降低HEAs的抗氧化性。(C)2013爱思唯尔有限公司版权所有。
High-entropy alloys (HEAs) are defined as the alloys composed of at least five principal elements in equimolar or near equimolar ratios, which can facilitate the formation of simple solid solutions during solidification. Recent studies suggested that the refractory HEAs exhibited great promise for high temperature structural materials. However, their oxidation behavior had received little attention. In the present study, Cr, Al and Si elements were added to improve the oxidation resistance, four types of new refractory HEAs were designed and synthesized, including NbCrMoTiAl0.5 (H-Ti), NbCrMoVAl0.5 (H-V), NbCrMoTiVAl0.5 (H-TiV) and NbCrMoTiVAl0.5Si0.3 (H-TiVSi0.3). Their microstructures and oxidation behavior were studied. As expected, these refractory HEAs mainly consist of a simple body-centred cubic (BCC) refractory metal solid solution (RMss) due to the high mixing entropy effect. Solidification process and thermodynamic analysis were investigated to explain the formation mechanism of their microstructures. For all the refractory HEAs, the oxidation kinetics at 1300 degrees C follows a linear behavior. The oxidation resistance of the HEAs is significantly improved with Ti and Si addition, but reduced with V addition. (C) 2013 Elsevier B.V. All rights reserved.