The origin of high-density dislocations in additively manufactured metals

• Main Authors: Ge Wang, Heng Ouyang, Chen Fan, Qiang Guo, Zhiqiang Li, Wentao Yan, Zan Li
• Format: Article
• Language: English
• Published: Taylor & Francis Group 2020-08-01
• Series: Materials Research Letters
• Subjects: additive manufacturing; cu; microstructure; dislocation; multi-physics modeling
• Online Access: http://dx.doi.org/10.1080/21663831.2020.1751739

The origin of dense dislocations in many additively manufactured metals remains a mystery. We here employed pure Cu as a prototype and fabricated the very challenging high-purity (>99.9%) bulk Cu by laser powder-bed-fusion (L-PBF) technique. We found that high-density dislocations were present in the as-built samples and these high-density dislocations were introduced on the fly during the L-PBF process. A newly developed multi-physics modeling was further employed to interpret the origin of these pre-existing dislocations, demonstrating that the compression-tension cycles rendered by the localized heating/cooling heterogeneity upon laser scanning are responsible for the residual high-density dislocations.