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Abstract
Magnesium alloys are considered as one of the most challenging materials to process via laser powder bed fusion (Selective Laser Melting, SLM). This is mainly due to their low evaporation temperature compared to e.g. aluminium or titanium alloys and an even higher reactivity. However, the demand for additively manufactured parts out of magnesium alloys is growing. Advantages of AM such as cost efficient prototyping, the manufacture of e.g. topology optimized parts for lightweight applications or even of individualized biodegradable implants with interconnected porosities could be realized by SLM of magnesium alloys.
This study will present solutions to overcome the challenges which arise when magnesium alloys are processed by means of SLM. Furthermore, the microstructure and mechanical properties of SLM parts out of the magnesium alloys AZ91 and WE43 are analysed. Finally, demonstrators for lightweight and medical applications are developed to demonstrate the feasibility to fabricate magnesium alloys complex parts by SLM.
Introduction
Magnesium alloys feature low density compared with high specific stiffness and are therefore used for many lightweight applications e.g. by the automotive and aerospace industries as well as in technical consumer products. In 2013 the first biodegradable implant, a compression screw made of a magnesium alloy, became commercially available by Syntellix AG [1] paving the way for novel biomedical applications. However being advantageous for many lightweight and medical applications, only few studies have been published to date addressing the manufacture of parts out of magnesium alloys with desirable quality by means of SLM [2-5]. Magnesium alloys are challenging materials to be processed by SLM due to their low evaporation temperature and high reactivity. This study will present solutions to overcome these challenges and showing microstructural and mechanical properties of asbuilt SLM parts out of the magnesium alloys AZ91 and WE43 as well as showing technological demonstrators for lightweight and biomedical applications.
Materials and Methods
For building test specimens out of magnesium alloys a build chamber based on Aconity3D system technology is used. It is equipped with an optical system consisting of an IPG single mode fiber laser YLR-200 with a maximum output power of 230 W, a galvanometric scanner Scanlab hurrySCAN 20 and a Sill f-theta lens S4LFT254 with a focal length of 254 mm. The laser spot has a Gaussian...