N F Shkodich, T Smoliarova, V Nallathambi, L M Feitosa, E Adabifiroozjaei, I Tarasov, M Grzywa, B Gault, S Reichenberger, L Molina-Luna, S Barcikowski, M Farle
{"title":"纳米晶CoMnFeNiGa高熵合金:室温铁磁性弥合了从体到纳米的差距。","authors":"N F Shkodich, T Smoliarova, V Nallathambi, L M Feitosa, E Adabifiroozjaei, I Tarasov, M Grzywa, B Gault, S Reichenberger, L Molina-Luna, S Barcikowski, M Farle","doi":"10.1039/d5fd00080g","DOIUrl":null,"url":null,"abstract":"<p><p>Nanocrystalline CoMnFeNiGa high entropy alloys (HEAs) were successfully synthesized and characterized across different length scales. Compositionally homogeneous single-phase FCC HEA micropowder particles with a nanocrystalline structure (∼8 nm) were produced by short-term (190 min) high energy ball milling (HEBM). These powders were subsequently used as precursors for fabricating dense HEA bulk by spark plasma sintering (SPS) and HEA nanoparticles (NPs) by laser fragmentation in liquids (LFL)-both synthesis routes are not achievable by direct processing of elemental powder blends. We show that the single-phase FCC CoMnFeNiGa HEA micropowder partially transforms into a BCC phase upon consolidation by SPS at 1073 K. As a result, the HEA bulk consists of a mixture of FCC and BCC phases. In addition, Mn-rich BCC precipitates (10-50 nm) were formed in both HEA phases. The LFL of HEA micropowder leads to a formation of HEA NPs with two morphologies (spheres and quasi-2D platelets with 5-10 nm thickness and 40-150 nm lengths) with FCC, BCC, and hexagonal structures (birnessite-type layered δ-MnO<sub>2</sub> structure). All three nanocrystalline CoMnFeNiGa HEAs exhibit soft ferromagnetic behavior at RT with a saturation magnetization (<i>M</i><sub>s</sub>) of 19.5-33.5 A m<sup>2</sup> kg<sup>-1</sup> for the micropowder and NPs, while the <i>M</i><sub>s</sub> of HEA bulk is 2-4 times larger (88.8 A m<sup>2</sup> kg<sup>-1</sup>). A short thermal treatment (1000 K, 30 s) significantly enhanced <i>M</i><sub>s</sub> and increased the Curie temperature of the micropowder to 105.6 A m<sup>2</sup> kg<sup>-1</sup> and 785 K, of the NPs to 46.9 A m<sup>2</sup> kg<sup>-1</sup> and 850 K, and of the bulk material to 106 A m<sup>2</sup> kg<sup>-1</sup> and 793 K. The coercivity increased threefold to 1.8 kA m<sup>-1</sup> only in NPs. Structure-property relationships in CoMnFeNiGa HEAs are herein systematically compared across all length scales, demonstrating that magnetic behavior can be effectively tuned by nanoscale structural control and rapid thermal treatment.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":""},"PeriodicalIF":3.1000,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Nanocrystalline CoMnFeNiGa high entropy alloys: room temperature ferromagnetism bridging the gap from bulk to nano.\",\"authors\":\"N F Shkodich, T Smoliarova, V Nallathambi, L M Feitosa, E Adabifiroozjaei, I Tarasov, M Grzywa, B Gault, S Reichenberger, L Molina-Luna, S Barcikowski, M Farle\",\"doi\":\"10.1039/d5fd00080g\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>Nanocrystalline CoMnFeNiGa high entropy alloys (HEAs) were successfully synthesized and characterized across different length scales. Compositionally homogeneous single-phase FCC HEA micropowder particles with a nanocrystalline structure (∼8 nm) were produced by short-term (190 min) high energy ball milling (HEBM). These powders were subsequently used as precursors for fabricating dense HEA bulk by spark plasma sintering (SPS) and HEA nanoparticles (NPs) by laser fragmentation in liquids (LFL)-both synthesis routes are not achievable by direct processing of elemental powder blends. We show that the single-phase FCC CoMnFeNiGa HEA micropowder partially transforms into a BCC phase upon consolidation by SPS at 1073 K. As a result, the HEA bulk consists of a mixture of FCC and BCC phases. In addition, Mn-rich BCC precipitates (10-50 nm) were formed in both HEA phases. The LFL of HEA micropowder leads to a formation of HEA NPs with two morphologies (spheres and quasi-2D platelets with 5-10 nm thickness and 40-150 nm lengths) with FCC, BCC, and hexagonal structures (birnessite-type layered δ-MnO<sub>2</sub> structure). All three nanocrystalline CoMnFeNiGa HEAs exhibit soft ferromagnetic behavior at RT with a saturation magnetization (<i>M</i><sub>s</sub>) of 19.5-33.5 A m<sup>2</sup> kg<sup>-1</sup> for the micropowder and NPs, while the <i>M</i><sub>s</sub> of HEA bulk is 2-4 times larger (88.8 A m<sup>2</sup> kg<sup>-1</sup>). A short thermal treatment (1000 K, 30 s) significantly enhanced <i>M</i><sub>s</sub> and increased the Curie temperature of the micropowder to 105.6 A m<sup>2</sup> kg<sup>-1</sup> and 785 K, of the NPs to 46.9 A m<sup>2</sup> kg<sup>-1</sup> and 850 K, and of the bulk material to 106 A m<sup>2</sup> kg<sup>-1</sup> and 793 K. The coercivity increased threefold to 1.8 kA m<sup>-1</sup> only in NPs. Structure-property relationships in CoMnFeNiGa HEAs are herein systematically compared across all length scales, demonstrating that magnetic behavior can be effectively tuned by nanoscale structural control and rapid thermal treatment.</p>\",\"PeriodicalId\":76,\"journal\":{\"name\":\"Faraday Discussions\",\"volume\":\" \",\"pages\":\"\"},\"PeriodicalIF\":3.1000,\"publicationDate\":\"2025-10-10\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Faraday Discussions\",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://doi.org/10.1039/d5fd00080g\",\"RegionNum\":3,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Faraday Discussions","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1039/d5fd00080g","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
摘要
成功合成了纳米晶CoMnFeNiGa高熵合金(HEAs),并对其进行了不同长度尺度的表征。采用短期(190 min)高能球磨(HEBM)法制备了具有纳米晶结构(~ 8 nm)的单相FCC HEA微粉颗粒。这些粉末随后被用作火花等离子烧结(SPS)和激光在液体中破碎(LFL)制备高密度HEA体和HEA纳米颗粒(NPs)的前驱体——这两种合成路线都不能通过直接加工元素粉末混合物来实现。结果表明,在1073 K下SPS固结后,单相FCC comneniga HEA微粉部分转变为BCC相。因此,HEA体由FCC相和BCC相的混合物组成。此外,HEA相和HEA相均形成了10 ~ 50 nm的富锰BCC相。HEA微粉的LFL导致HEA NPs具有两种形态(5-10 nm厚度和40-150 nm长度的球状和准二维片状),具有FCC、BCC和六边形结构(birnite型层状δ-MnO2结构)。三种纳米晶comneniga HEAs在室温下均表现出软铁磁行为,微粉和NPs的饱和磁化强度(Ms)为19.5 ~ 33.5 a m2 kg-1,而HEA体的Ms是前者的2 ~ 4倍(88.8 a m2 kg-1)。短时间热处理(1000 K, 30 s)显著提高了Ms,使微粉的居里温度提高到105.6 A m2 kg-1和785 K, NPs的居里温度提高到46.9 A m2 kg-1和850 K,散装材料的居里温度提高到106 A m2 kg-1和793 K。仅在NPs中矫顽力增加了三倍,达到1.8 kA m-1。本文系统地比较了comneniga HEAs在所有长度尺度上的结构-性能关系,证明了磁性行为可以通过纳米级结构控制和快速热处理来有效调节。
Nanocrystalline CoMnFeNiGa high entropy alloys: room temperature ferromagnetism bridging the gap from bulk to nano.
Nanocrystalline CoMnFeNiGa high entropy alloys (HEAs) were successfully synthesized and characterized across different length scales. Compositionally homogeneous single-phase FCC HEA micropowder particles with a nanocrystalline structure (∼8 nm) were produced by short-term (190 min) high energy ball milling (HEBM). These powders were subsequently used as precursors for fabricating dense HEA bulk by spark plasma sintering (SPS) and HEA nanoparticles (NPs) by laser fragmentation in liquids (LFL)-both synthesis routes are not achievable by direct processing of elemental powder blends. We show that the single-phase FCC CoMnFeNiGa HEA micropowder partially transforms into a BCC phase upon consolidation by SPS at 1073 K. As a result, the HEA bulk consists of a mixture of FCC and BCC phases. In addition, Mn-rich BCC precipitates (10-50 nm) were formed in both HEA phases. The LFL of HEA micropowder leads to a formation of HEA NPs with two morphologies (spheres and quasi-2D platelets with 5-10 nm thickness and 40-150 nm lengths) with FCC, BCC, and hexagonal structures (birnessite-type layered δ-MnO2 structure). All three nanocrystalline CoMnFeNiGa HEAs exhibit soft ferromagnetic behavior at RT with a saturation magnetization (Ms) of 19.5-33.5 A m2 kg-1 for the micropowder and NPs, while the Ms of HEA bulk is 2-4 times larger (88.8 A m2 kg-1). A short thermal treatment (1000 K, 30 s) significantly enhanced Ms and increased the Curie temperature of the micropowder to 105.6 A m2 kg-1 and 785 K, of the NPs to 46.9 A m2 kg-1 and 850 K, and of the bulk material to 106 A m2 kg-1 and 793 K. The coercivity increased threefold to 1.8 kA m-1 only in NPs. Structure-property relationships in CoMnFeNiGa HEAs are herein systematically compared across all length scales, demonstrating that magnetic behavior can be effectively tuned by nanoscale structural control and rapid thermal treatment.