In this work, microstructural and mechanical response to hydrogen were investigated for CoCrFeMnNi high-entropy alloy (HEA) additively manufactured by selective laser melting (SLM) with and without heat treatment. Microstructural characterization, thermal desorption analyses, and slow-strain-rate tests were conducted to study the hydrogen trapping behavior and the effects of hydrogen on the deformation and fracture mechanism. The results showed that cell walls with high-density dislocations and Mn segregation provided hydrogen trapping and increased the high hydrogen capacity. This caused hydrogen embrittlement, accompanied by hydrogen-assisted intergranular cracking in as-built CoCrFeMnNi HEA. A heat treatment at 900 ℃ reduced dislocation density of the walls and eliminated the Mn segregation. Interestingly, hydrogen-induced ductilization was enabled in the heat-treated-SLM HEA. This is attributed to an appropriate twinability and twinning strain which greatly suppressed intergranular cracking in the surface layer. Therefore, tuning twinability through the control of microstructure is critical for a transition from hydrogen embrittlement to ductilization for SLM-built HEA.

在这项工作中，研究了通过选择性激光熔化 (SLM) 和不经过热处理的增材制造的 CoCrFeMnNi 高熵合金 (HEA) 对氢的微观结构和机械响应。进行了微观结构表征、热解吸分析和慢应变速率测试，以研究氢捕获行为和氢对变形和断裂机制的影响。结果表明，具有高密度位错和Mn偏析的细胞壁提供了氢捕获并增加了高氢容量。这会导致氢脆，并在完工的 CoCrFeMnNi HEA 中伴随氢辅助晶间开裂。900 ℃热处理降低了壁的位错密度并消除了Mn偏析。有趣的是，在热处理的 SLM HEA 中实现了氢诱导延展化。这归因于适当的孪晶性和孪晶应变，极大地抑制了表面层的晶间裂纹。因此，通过控制微观结构来调整孪晶性对于 SLM 构建的 HEA 从氢脆到延展性的转变至关重要。