Selective laser melting of an Al86Ni6Y4.5Co2La1.5 metallic glass: Processing, microstructure evolution and mechanical properties
Selective laser melting of an Al86Ni6Y4.5Co2La1.5 metallic glass: Processing, microstructure evolution and mechanical properties
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DOI：
10.1016/j.msea.2014.03.097
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发表时间：
2014-06-12
期刊：
影响因子：
6.4
通讯作者：
Sercombe, T. B.
中科院分区：
文献类型：
--
作者：
Li, X. P.;Kang, C. W.;Sercombe, T. B.
在这项研究中，单线扫描在不同的激光功率进行选择性激光熔化（SLM）设备上的预制多孔Al 86 Ni 6 Y 4. 5 Co 2 La 1. 5金属玻璃（MG）预制件。系统地研究了扫描轨迹的致密化、组织演变、相变和力学性能。结果表明，激光束的能量分布以及熔池内对流与导热的换热竞争对扫描轨迹的形貌有重要影响。由于激光能量和传热过程的高斯分布，扫描轨迹的不同区域经历了不同的热历史，导致组织和力学性能呈梯度变化。较高的激光功率会导致较高的热应力，从而导致裂纹的形成;而低功率则会降低激光轨迹的强度，也会导致裂纹。在高激光功率下的热波动产生了不均匀的化学分布，这引起了MG的严重结晶，尽管高冷却速率。在热影响区（HAZ）和熔池边缘都发生了结晶。然而，通过选择适当的激光功率，可以产生无裂纹的扫描轨迹，而没有结晶。这项工作提供了必要的基本理解，将导致制造大尺寸，无裂纹MG与高密度，可控的微观结构和机械性能使用SLM。(C)2014爱思唯尔有限公司版权所有。
In this study, single line scans at different laser powers were carried out using selective laser meting (SLM) equipment on a pre-fabricated porous Al86Ni6Y4.5Co2La1.5 metallic glass (MG) preform. The densification, microstructural evolution, phase transformation and mechanical properties of the scan tracks were systematically investigated. It was found that the morphology of the scan track was influenced by the energy distribution of the laser beam and the heat transfer competition between convection and conduction in the melt pool. Due to the Gaussian distribution of laser energy and heat transfer process, different regions of the scan track experienced different thermal histories, resulting in a gradient microstructure and mechanical properties. Higher laser powers caused higher thermal stresses, which led to the formation of cracks; while low power reduced the strength of the laser track, also inducing cracking. The thermal fluctuation at high laser power produced an inhomogeneous chemical distribution which gave rise to severe crystallization of the MG, despite the high cooling rate. The crystallization occurred both within the heat affected zone (HAZ) and at the edge of melt pool. However, by choosing an appropriate laser power crack-free scan tracks could be produced with no crystallization. This work provides the necessary fundamental understanding that will lead to the fabrication of large-size, crack-free MG with high density, controllable microstructure and mechanical properties using SLM. (C) 2014 Elsevier B.V. All rights reserved.