High Temperature and Ion Implantation-Induced Phase Transformations in Novel Reduced Activation Si-Fe-V-Cr (-Mo) High Entropy Alloys
High Temperature and Ion Implantation-Induced Phase Transformations in Novel Reduced Activation Si-Fe-V-Cr (-Mo) High Entropy Alloys
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DOI：
10.3389/fmats.2019.00146
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发表时间：
2019-06
影响因子：
3.2
通讯作者：
A. Gandy;Bethany Jim;G. Coe;D. Patel;L. Hardwick;S. Akhmadaliev;Nik Reeves-McLaren;R. Goodall
中科院分区：
文献类型：
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作者：
A. Gandy;Bethany Jim;G. Coe;D. Patel;L. Hardwick;S. Akhmadaliev;Nik Reeves-McLaren;R. Goodall
为了实现聚变作为一种安全、可持续的能源，需要开发能够承受高温和独特的聚变辐射环境的新型结构材料。聚变的一个吸引人的方面是不会产生长寿命的放射性废物，但要实现这一点，结构材料必须包含减少的激活元素。成分复杂合金(CCA)(也称为高熵合金，HEA)在包括聚变在内的极端环境中具有很好的应用前景，但到目前为止，很少有报道具有低活化度。为了解决这些材料方面的挑战，我们用电弧熔化的方法制造了新型的、低活化的HEAs，并用5 MeV的Au2+离子注入研究了它们的热稳定性和抗辐射损伤性能。虽然这些合金被设计成形成单相的体心立方，但通过室温和非常温原位X射线衍射，我们发现这些合金的热力学稳定结构实际上是一个sigma相。我们认为，在这些合金中形成了体心立方相，但在高温下(>；1000°C)。在重离子注入过程中还形成了体心立方相，我们认为这是由于在热峰期间发生的快速加热和冷却，有效地冻结了注入诱导相变所产生的体心立方相。研究发现，体心立方相具有较高的硬度和一定程度的延展性，这使得这些新合金在开发核电用低活性HEA方面颇具吸引力。
For fusion to be realised as a safe, sustainable source of power, new structural materials need to be developed which can withstand high temperatures and the unique fusion radiation environment. An attractive aspect of fusion is that no long-lived radioactive wastes will be produced, but to achieve this structural materials must comprise reduced activation elements. Compositionally complex alloys (CCAs) (also called high entropy alloys, HEAs) are promising candidates for use in extreme environments, including fusion, but few reported to date have low activation. To address these material challenges we have produced novel, reduced activation, HEAs by arc-melting, and investigated their thermal stability, and radiation damage resistance using 5 MeV Au2+ ion implantation. Whilst the alloys were designed to form single phase BCC, using room temperature and non-ambient in situ X-ray diffraction we have revealed the thermodynamically stable structure of these alloys is in fact a sigma phase. We propose that a BCC phase is formed in these alloys, but at high temperatures (> 1000 °C). A BCC phase was also formed during heavy ion implantation, which we propose to be due to the rapid heating and cooling that occurs during the thermal spike, effectively freezing in the BCC phase produced by an implantation induced phase transformation. The BCC phase was found to have high hardness and a degree of ductility, making these new alloys attractive in the development of reduced activation HEAs for nuclear applications.