{"title":"Interstitial engineering enabling superior mechanical properties of nitrogen-supersaturated Fe50Mn30Co10Cr10 high-entropy alloys","authors":"","doi":"10.1016/j.actamat.2024.120214","DOIUrl":null,"url":null,"abstract":"<div><p>Interstitial atoms are key in modifying microstructures and enhancing mechanical properties of metals. Traditionally, the introduction of interstitial elements into metal matrices has been limited to low levels (< 2 at.%) to avoid the formation of brittle ceramics, constraining the exploitation of their full strengthening potential. This study introduces nitrogen-supersaturated high-entropy alloys (HEAs) with up to 28.9 at.% nitrogen, achieving substantial interstitial strengthening and phase adjustment. Remarkably, these HEAs remain solid solution phases without nitride formation, even at exceptionally high nitrogen levels. The microstructural evolution with increasing nitrogen content transitions from a single face-centred cubic (FCC) structure to a dual-phase structure of FCC and hexagonal close-packed (HCP) phases, and ultimately reverts to a predominantly FCC structure. These alloys achieve an impressive hardness of ∼ 20 GPa, comparable to ceramics, while maintaining exceptional damage-tolerance and plasticity. The outstanding mechanical properties are attributed to massive solid solution strengthening from a high nitrogen level, a hierarchical dual-phase structure, and stress-induced phase transformation from FCC to HCP. Contrary to the brittleness typical of nitrides, these nitrogen-supersaturated HEAs exhibit substantial plastic deformation akin to metallic materials, thus opening up a new pathway for enhancing the mechanical performance of advanced alloys under extreme loading conditions.</p></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":null,"pages":null},"PeriodicalIF":8.3000,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Materialia","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1359645424005640","RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Interstitial atoms are key in modifying microstructures and enhancing mechanical properties of metals. Traditionally, the introduction of interstitial elements into metal matrices has been limited to low levels (< 2 at.%) to avoid the formation of brittle ceramics, constraining the exploitation of their full strengthening potential. This study introduces nitrogen-supersaturated high-entropy alloys (HEAs) with up to 28.9 at.% nitrogen, achieving substantial interstitial strengthening and phase adjustment. Remarkably, these HEAs remain solid solution phases without nitride formation, even at exceptionally high nitrogen levels. The microstructural evolution with increasing nitrogen content transitions from a single face-centred cubic (FCC) structure to a dual-phase structure of FCC and hexagonal close-packed (HCP) phases, and ultimately reverts to a predominantly FCC structure. These alloys achieve an impressive hardness of ∼ 20 GPa, comparable to ceramics, while maintaining exceptional damage-tolerance and plasticity. The outstanding mechanical properties are attributed to massive solid solution strengthening from a high nitrogen level, a hierarchical dual-phase structure, and stress-induced phase transformation from FCC to HCP. Contrary to the brittleness typical of nitrides, these nitrogen-supersaturated HEAs exhibit substantial plastic deformation akin to metallic materials, thus opening up a new pathway for enhancing the mechanical performance of advanced alloys under extreme loading conditions.
期刊介绍:
Acta Materialia serves as a platform for publishing full-length, original papers and commissioned overviews that contribute to a profound understanding of the correlation between the processing, structure, and properties of inorganic materials. The journal seeks papers with high impact potential or those that significantly propel the field forward. The scope includes the atomic and molecular arrangements, chemical and electronic structures, and microstructure of materials, focusing on their mechanical or functional behavior across all length scales, including nanostructures.