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Description
This study aims to investigate the influence of different process gases on the processing of a Zr-blended aluminum 7075 alloy by laser-based powder bed fusion. Two common gases for this process, argon and nitrogen, are compared. The objective is to study the effect of the gases on crack formation in the bulk material with respect to the possible formation of nitrides. In order to assess this phenomenon, bars at different heights will be printed with an in-situ change of the process gas in steps from pure argon to pure nitrogen. During the post-process analyses, special focus will be placed on investigating the crack formation. The preliminary results on specimens from initial build jobs showed differences in the cracking behavior with a varying amount of nitrogen in the process gas. A higher amount of cracking was found in the specimens produced with pure nitrogen compared to the specimens fabricated under argon atmosphere. This may be due to less Zr dissolved into the aluminum matrix under nitrogen processing conditions. The higher amount of cracks might therefore be attributed to the creation of fewer Al3Zr-precipitates that are needed for grain refinement and crack mitigation in this aluminum 7075 alloy.