Cracking mechanism and mechanical properties of selective laser melted CoCrFeMnNi high entropy alloy using different scanning strategies

There are increasing interests in fabricating CoCrFeMnNi high entropy alloy (HEA) using selective laser melting (SLM). However, cracks formed in as-built CoCrFeMnNi bulks may deteriorate the mechanical performance. This study adopted three scanning strategies to systematically reveal the characteristics and formation mechanism of cracks during SLM of CoCrFeMnNi. The experimental results demonstrate that the cracks form at right-angle-shaped high angle grain boundaries (HAGBs) without elemental segregation or precipitate. The upper part of crack exhibits features of hot cracking while the lower part is likely to form by the propagation of the upper part in solid-state during thermal shrinking and contraction. Besides, the scanning strategy can effectively manipulate not only the morphology and density of cracks, but also the mechanical properties of as-built parts. This work can help to further understand the cracking mechanism during SLM of CoCrFeMnNi and the effects of scanning strategy on microstructure and mechanical properties of as-built products.