On the role of atmospheric oxygen into mechanical properties and fracture behavior of selective laser melted AlCu5MnCdVA

Zhiheng Hu, Haihong Zhu, Xiaojia Nie, Changchun Zhang, Hu Zhang, Xiaoyan Zeng

Index: 10.1016/j.matdes.2018.04.003

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Abstract

In this study, the difference in the mechanical properties of AlCu5MnCdVA samples fabricated by selective laser melting (SLM) with different atmospheric oxygen content when it has little effect on the formability has been investigated and the mechanism of the earlier fracture has been proposed. The ultimate tensile strength and elongation of the samples fabricated with the atmospheric oxygen content below 20 ppm (LOC samples) are 10.89% and 128.21% higher than those of the samples fabricated with the atmospheric oxygen content below 200 ppm (HOC samples), respectively. By comparing the formability, density, microstructure, phase and fracture surface of the HOC samples and the LOC samples, it is found that the earlier fracture is caused by the larger size particles forming during the process. The chemical reaction rate dramatically increases as the atmospheric oxygen content increases. The closer particles and the longer duration of high temperature of the molten pool make the collision of the particles easier, resulting in the formation of the larger particles. These findings indicate the atmospheric oxygen plays a different role when alloys with high oxygen sensitivity are being selective laser melted.