Controlling melt flow by nanoparticles to eliminate surface wave induced surface fluctuation
Controlling melt flow by nanoparticles to eliminate surface wave induced surface fluctuation
复制标题
DOI：
10.1016/j.addma.2022.103081
复制
发表时间：
2022-08
影响因子：
11
通讯作者：
Minglei Qu;Qilin Guo;Luis I. Escano;Jiandong Yuan;S. Hojjatzadeh;S. Clark;K. Fezzaa;T. Sun
中科院分区：
文献类型：
--
作者：
Minglei Qu;Qilin Guo;Luis I. Escano;Jiandong Yuan;S. Hojjatzadeh;S. Clark;K. Fezzaa;T. Sun
高表面粗糙度是激光金属添加剂制造(AM)过程中遇到的主要挑战之一，与熔体流动行为密切相关。然而，如何控制激光金属AM加工过程中的熔体流动以改善表面光洁度还不是很清楚。本文首次采用Al6061+TiC纳米粒子体系，揭示了纳米粒子对激光熔池熔池各个位置熔体流动行为的影响，并通过使用TiC纳米粒子控制熔体流动和抑制表面波，实现了表面光洁度的显著改善。基于原位X射线成像观察，加入TiC纳米颗粒后，表面波被完全抑制，而在Al6061的LPBF过程中，没有纳米颗粒的表面波仅有56%的衰减。我们深入的现场X射线成像分析和粘度测量使我们能够确定，纳米颗粒引起的粘度增加通过(1)增加内部流体摩擦以更有效地降低波幅，(2)控制熔体流动以增加表面波数，(3)控制熔体流动以增加波的衰减时间，从而导致表面波的完全衰减。此外，我们还量化了增加流体摩阻、增加波数和增加衰减时间对波浪衰减的相对贡献，它们分别占61%、25%和14%。我们的研究为解决激光金属AM加工中的表面光洁度挑战提供了机理和潜在的方法。
The high surface roughness is one of the major challenges encountered in laser metal additive manufacturing (AM) processes, which is closely related to the melt flow behavior. However, how to control the melt flow in laser metal AM processes to improve surface finish is not clear. Here we reveal the effects of nanoparticles on melt flow behavior at every location of melt pool during laser metal AM process for the first time using Al6061 + TiC nanoparticles system and achieve significant improvement of surface finish by using TiC nanoparticles to control the melt flow and damp the surface wave. Based on the in-situ x-ray imaging observation, the surface wave is fully damped after adding TiC nanoparticles, compared with only 56% damping without nanoparticles during LPBF of Al6061. Our in-depth in-situ x-ray imaging analysis and viscosity measurement enable us to identify that nanoparticle-induced increase of viscosity causes the fully damping of the surface wave by (1) increasing the internal fluid friction for more efficient wave amplitude reduction, (2) controlling the melt flow to increase the surface wave number, (3) controlling the melt flow to increase the wave damping time. Furthermore, we also quantified the relative contributions of increasing fluid friction, increasing wave number and increasing damping time to wave damping, which account for 61%, 25% and 14%, respectively. Our research provides the mechanisms and potential method to address the surface finish challenge in laser metal AM processes.