Ordered nitrogen complexes overcoming strength–ductility trade-off in an additively manufactured high-entropy alloy
Ordered nitrogen complexes overcoming strength–ductility trade-off in an additively manufactured high-entropy alloy
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DOI：
10.1080/17452759.2020.1840783
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发表时间：
2020-12
影响因子：
10.6
通讯作者：
Dandan Zhao;Quan Yang;Dawei Wang;M. Yan;Pei Wang;Mingguang Jiang;Changyong Liu;Dong-feng Diao-Dong-feng-Di
中科院分区：
文献类型：
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作者：
Dandan Zhao;Quan Yang;Dawei Wang;M. Yan;Pei Wang;Mingguang Jiang;Changyong Liu;Dong-feng Diao-Dong-feng-Di
摘要：在反应性 N2 气氛下通过激光粉末床熔合 (LBPF) 增材制造的 CoCrFeMnNi 高熵合金的强度和延展性同时得到增强。研究发现，氮原子在增材制造过程中吸收，在 HEA 基质的八面体间隙位置形成有序氮络合物 (ONC)。 LPBF 期间 ONC 的形成促进了位错增殖，从而导致位错单元更小，位错密度更高。位错强化与间隙强化相结合，使增材制造的 HEA 的屈服强度达到 690 MPa，比惰性气氛下制造的同类产品高 15%。更有趣的是，ONCs 刺激位错成核并产生更异质的微观结构，从而产生 15.3% 的出色延展性，增加了 34%。因此，在反应气氛下的 LPBF 过程中，通过氮掺杂成功扭转了强度-延展性的权衡。
ABSTRACT Strength and ductility were simultaneously enhanced in the additively manufactured CoCrFeMnNi high-entropy alloy by laser powder bed fusion (LBPF) under reactive N2 atmosphere. It was found that nitrogen atoms picked up during additive manufacturing line-up to form ordered nitrogen complexes (ONCs) in the octahedral interstitial position of the HEA matrix. Dislocation multiplication is then facilitated by the formation of ONCs during LPBF, leading to a higher dislocation density with smaller dislocation cells. Dislocation strengthening, combined with interstitial strengthening, endows the additively manufactured HEA with the yielding strength of 690 MPa, 15% higher than that of the counterparts fabricated under inert atmosphere. More interestingly, the ONCs stimulate dislocation nucleation and engender more heterogeneous microstructure, giving rise to an outstanding ductility of 15.3%, with an increment of 34%. As a result, the strength–ductility trade-off was successfully reversed by the nitrogen doping during LPBF under reactive atmosphere.