Lamellar instabilities during scanning laser melting of Al–Cu eutectic and hypoeutectic thin films
Lamellar instabilities during scanning laser melting of Al–Cu eutectic and hypoeutectic thin films
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Al-Cu共晶和亚共晶薄膜扫描激光熔化过程中的层状不稳定性
DOI：
10.1016/j.jallcom.2021.158800
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发表时间：
2021
影响因子：
6.2
通讯作者：
Floro, J.A.
中科院分区：
文献类型：
--
作者：
Sullivan, E.J.;Tomko, J.A.;Skelton, J.M.;Fitz-Gerald, J.M.;Hopkins, P.E.;Floro, J.A.
采用扫描激光熔化法研究了200和500 nm厚Al-Cu薄膜的定向凝固过程。采用磁控溅射法制备了共晶和亚共晶Al-Cu合金薄膜。用连续波激光在空气中进行薄膜的熔化，扫描速度v的函数为5cm /s。对于共晶薄膜，在整个研究速度范围内观察到规则的片层微观结构。很容易产生50 nm以下的层间间距λ。结果与体Al-Cu合金的研究结果一致，符合经典的稳态片层生长关系λ2v = K，但薄膜中的常数K值明显大于体Al-Cu合金。这是由于二维共晶系统的间距调整机制的限制。在亚共晶薄膜中，随着扫描速度的降低，可以观察到复杂的片层结构。直片层、振荡片层、孤立的倾斜波和反复出现的极端片层分支事件在融化轨迹上共存。采用傅里叶分析方法对膜的混沌面积分数进行量化。随着G/v比的增加，向混沌的转变发生了，这是由于从上面接近再入共晶到枝晶的转变。讨论了进一步细化共晶薄膜激光熔化以更好地控制凝固过程的方法。
Scanning laser melting was employed to investigate directional solidification in Al–Cu thin films, 200 and 500 nm thick. The Al–Cu alloy films, with both eutectic and hypoeutectic compositions, were co-deposited on fused silica substrates by magnetron sputtering. Melting of the films was carried out in air using a CW laser, as a function of the scan velocity, v, up to 5 cm/s. For eutectic films, regular lamellar microstructure was observed over the entire range of velocities studied. Interlamellar spacings, λ, below 50 nm were readily produced. Results were found to be consistent with studies on bulk Al–Cu alloys, obeying the classic steady state lamellar growth relationship, λ2v = K. However, the value of the constant, K is significantly larger in thin films when compared to bulk. This is attributed to constraints on mechanisms for spacing adjustment in two-dimensional eutectic systems. In the hypoeutectic thin films, a complex lamellar structure was observed as the scan velocity was reduced. Regions of straight lamellae, oscillatory lamellae, solitary tilt waves, and recurring extreme lamellar branching events coexisted across the melt track. Fourier analysis was used to quantify the chaotic area fraction of the films. The transition to chaos occurred as the G/v ratio increased, attributed to approaching a re-entrant eutectic-to-dendritic transition from above. Approaches to further refine laser melting in thin eutectic films in order to better control solidification processes are discussed.
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DOI：
--
发表时间：
1981
期刊：
影响因子：
--
作者：
H. Cline
通讯作者：
H. Cline
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DOI：
--
发表时间：
1987
期刊：
影响因子：
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作者：
B. Ditchek
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B. Ditchek
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DOI：
--
发表时间：
1995
期刊：
影响因子：
--
作者：
P. Gilgien;A. Zryd;W. Kurz
通讯作者：
W. Kurz
DOI：
10.1016/0956-7151(93)90237-m
发表时间：
1993-12-01
期刊：
ACTA METALLURGICA ET MATERIALIA
影响因子：
--
作者：
GILL, SC;KURZ, W
通讯作者：
KURZ, W
影响因子：
1.6
作者：
D. Cooksey;D. Munson;M. Wilkinson;A. Hellawell
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D. Cooksey;D. Munson;M. Wilkinson;A. Hellawell