Abstract

An equiatomic CoCrFeMnNi high entropy alloy (HEA) coating layer was prepared via a cold spray (CS) process. In order to control the microstructure and nano-indentation properties of the CS HEA, heat treatments were employed. CS HEA coating layer showed a heterogeneous microstructure where ultra-fine grains were formed at the particle interfaces, while coarse grains were formed inside the particles. Furthermore, deformation twins (DTs) were also formed inside the particles due to severe plastic deformation (SPD) in each particle generated during the CS deposition. For the 550 °C heat treatment (HT), fine Cr-rich precipitates were additionally formed at the grain boundary and particle boundary. By contrast, recrystallization occurred during 850 °C HT, while the size of the Cr-rich precipitate increased. The nano-indentation hardness of the CS HEA coating layer was 10.9 GPa, which was ~ 3 times higher than that of the conventional cast HEA. The superior hardness of the CS HEA might has been enabled due to the combination of the high dislocation density, DTs, and ultra-fine grains. Based on the results above, the strategy to control the microstructure and mechanical properties through HT of the equiatomic CoCrFeMnNi HEA coating layer prepared via the CS process has been discussed.

Graphic Abstract

中文翻译：

---

调整冷喷涂等原子CoCrFeMnNi高熵合金涂层的组织和力学性能

摘要

通过冷喷涂（CS）工艺制备了等原子的CoCrFeMnNi高熵合金（HEA）涂层。为了控制CS HEA的微观结构和纳米压痕性能，采用了热处理。CS HEA涂层显示出异质的微观结构，其中在颗粒界面处形成超细晶粒，而在颗粒内部形成粗晶粒。此外，由于在CS沉积期间产生的每个粒子中的严重塑性变形（SPD），在粒子内部也形成了变形孪晶（DTs）。对于550°C的热处理（HT），在晶界和颗粒边界处还形成了细的富Cr沉淀。相比之下，在850°C HT期间发生重结晶，而富Cr沉淀的尺寸增加。CS HEA涂层的纳米压痕硬度为10.9 GPa，是传统铸造HEA的〜3倍。由于高位错密度，DT和超细晶粒的结合，CS HEA可能具有出色的硬度。基于以上结果，讨论了通过CS工艺制备的等原子CoCrFeMnNi HEA涂层通过HT控制组织和力学性能的策略。

图形摘要