Complications of using thin film geometries for nanocrystalline thermal stability investigations
Complications of using thin film geometries for nanocrystalline thermal stability investigations
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DOI：
10.1557/jmr.2020.174
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发表时间：
2020-07
影响因子：
2.7
通讯作者：
Xuyang Zhou;Tyler Kaub;F. Vogel;G. Thompson
中科院分区：
文献类型：
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作者：
Xuyang Zhou;Tyler Kaub;F. Vogel;G. Thompson
本文报道了溅射沉积Cu-7V和Cu-27 V（at.%）合金膜，试图产生“干净”的合金，以研究纳米晶的稳定性。在高真空室中生长的薄膜可以减轻工艺污染，这涉及到纳米晶稳定性机制的识别。初始膜非常干净，碳和氧含量在~0.01原子%和0.38原子%之间。在400 °C/1 h的退火促进了钒在大角度晶界三重结处的聚集。在800 °C/1 h退火下，Cu-7V膜失去其纳米晶晶粒尺寸，钒分配到自由表面; Cu-27 V保留其纳米晶晶粒，在基体中具有钒簇，但存在表面溶质偏析。虽然最初的合金和真空退火保持低污染水平的要求，高表面积与体积比的膜，加上高偏析的倾向，使这个系统相分离的方式，要研究的稳定性机制，在高温下丢失。这说明了使用薄膜解决纳米晶稳定性的障碍。
We report the sputter deposition of Cu-7V and Cu-27V (at.%) alloy films in an attempt to yield a “clean” alloy to investigate nanocrystalline stability. Films grown in high vacuum chambers can mitigate processing contaminates which convolute the identification of nanocrystalline stability mechanism(s). The initial films were very clean with carbon and oxygen contents ranging between ~0.01 and 0.38 at.%. Annealing at 400 °C/1 h facilitated the clustering of vanadium at high-angle grain boundary triple junctions. At 800 °C/1 h annealing, the Cu-7V film lost its nanocrystalline grain sizes with the vanadium partitioned to the free surface; the Cu-27V retained its nanocrystalline grains with vanadium clusters in the matrix, but surface solute segregation was present. Though the initial alloy and vacuum annealing retained the low contamination levels sought, the high surface area-to-volume ratio of the film, coupled with high segregation tendencies, enabled this system to phase separate in such a manner that the stability mechanisms that were to be studied were lost at high temperatures. This illustrates obstacles in using thin films to address nanocrystalline stability.