Details

Autor(en) / Beteiligte

• Lin, Yi-Ting
• An, Xianghai
• Zhu, Zhiguang
• Nai, Mui Ling Sharon
• Tsai, Che-Wei
• Yen, Hung-Wei

Titel

Effect of cell wall on hydrogen response in CoCrFeMnNi high-entropy alloy additively manufactured by selective laser melting

Ist Teil von

• Journal of alloys and compounds, 2022-12, Vol.925, p.166735, Article 166735

Ort / Verlag

Lausanne: Elsevier B.V

Erscheinungsjahr

2022

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• 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. [Display omitted] •Cell-wall engineering enables a change in mechanical response to hydrogen in CoCrFeMnNi HEA processed by SLM.•Cell walls combined with Mn segregation in as-built CoCrFeMnNi HEA provide trapping sites for hydrogen.•A high twinability under high flow stress and high hydrogen concentration promotes hydrogen embrittlement in as-built HEA.•A heat treatment at 900 ℃ reduced dislocation density at cell wall, which reduces the capability of hydrogen trapping.•An appropriate twinability due to cell-wall modification led to hydrogen-induced ductilization in heat-treated HEA.