Comprehensive assessment of the printability of CoNiCrFeMn in laser powder bed fusion

Abstract

This study assesses the printability including the consolidation, solidification microstructure, and mechanical properties of the CoCrFeMnNi high entropy alloy fabricated by laser powder bed fusion. A range of print parameters was used for a comprehensive assessment of printability, providing a basis to establish the relationship between process, microstructure, and mechanical properties. The study demonstrates a high relative density of the alloy fabricated with energy density in the range 62.7-109.8 J/mm3. It is shown that the scan strategy plays an important role in consolidation. For the same energy density, the rotation of 67° between two consecutive layers tends to yield higher consolidation than other considered strategies. Moreover, the scan strategy is found to be most influential in microstructure development. The scan strategy rotation angle controls the extent to which epitaxial growth can occur, and hence the crystallographic texture and the grain morphology. Amongst four considered strategies, the 0°- and 90°-rotation meander led to the strongest preferred texture while the 67°-rotation resulted in weaker texture. The 67°-rotation strategies led to broadened grains with lower aspect ratios. The understanding of texture and grain size provides explanations to the observed mechanical properties (such as flow stress and plastic anisotropy) of the alloy.