The origin of high-density dislocations in additively manufactured metals
Ge Wang, Heng Ouyang, Fan Chen, Qiang Guo, Zhiqiang Li, Zhiqiang Li, Wentao Yan, Zan Li, Zan Li
Abstract
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.