摘要
采用差热分析法研究了Nd_9Fe_(72)Ti_4C_2B_(13)永磁合金形核过冷度ΔT^-与其熔体过热度ΔT^+的关系。在此基础上,通过对不同熔体过热度的薄带进行微观结构分析、热分析和磁性能测试,研究了熔体过热度对合金的非晶形成能力、组织演化和磁性能的影响。结果表明,合金的过冷度拐点对应的临界过热度为67K。在8~67K的过热度范围内,ΔT^-随ΔT^+的提高而急剧增大了58K;而在67~146K的过热度范围内,ΔT^-随ΔT^+而变化的幅度不大,其间的平均过冷度达到了181K。ΔT^+为60K的快淬薄带的微观组织由Nd_2Fe_(14)B、Fe_3B、α-Fe、Nd_2Fe_(23)B_3相的纳米晶和少量非晶组成。随着ΔT^+从60K提高至130K,快淬薄带中的Nd_2Fe_(23)B_3、α-Fe和Fe_3B纳米晶逐步消失,而非晶含量逐步增大,最终得到完全非晶。ΔT^+为60K的薄带退火组织中存在有损于磁性的亚稳相Nd_2Fe_(23)B_3,其磁性能低下;而ΔT^+分别为90,110和130K的薄带退火组织均由Nd_2Fe_(14)B、Fe_3B、和α-Fe纳米晶组成,它们的磁性能较ΔT^+为60K的薄带的大幅提高。其中,ΔT^+为90K的退火薄带的磁性能取得了最大值,其最佳值为H_(ci)=521.57kA/m,B_r=0.75T,(BH)_(max)=66.31kJ/m^3,M_r/M_s=0.67。
The dependence of the nucleation undercooling degreeΔT-of Nd9Fe72Ti4C2B13 permanent magnetic alloy on its melt overheating degreeΔT+was studied by differential thermal analysis.On this basis,the effects of the melt overheating degree on the glass formability,microstructure evolution and magnetic properties of the alloy were investigated by thermal analysis combining with microstructure analysis and magnetic properties test of the ribbons melt-spun at different melt overheating degree.The results show that the melt overheating degree threshold of the alloy corresponding to its turning points of the mean undercooling degree is found to be 67 K.TheΔT-increases sharply by 58 K with theΔT+increasing during the range of 8-67 K,but it increases a little and the mean undercooling degree reaches 181 K when theΔT+raises during 67-146 K.The microstructure of the ribbon melt-spun atΔT+=60 K is composed with Nd2Fe14 B,Fe3B,α-Fe,Nd2Fe23B3 and a small amount of amorphous phases.And the amorphous content increases gradually while the Nd2Fe23B3,α-Fe and Fe3B nanocrystals gradually disappear asΔT+raises from 60 to 130 K,and the completely amorphous structure is obtained when theΔT+reaches 130 K.The metastable phase Nd2Fe23B3 that is detrimental to magnetic properties exists in the annealed ribbon melt-spun atΔT+=60 K,causing its magnetic properties to be very low.But only Nd2Fe14B,Fe3B andα-Fe nanocrystals are found in the annealed ribbons melt-spun respectively atΔT+=90,110 and 130 K,and the magnetic properties of these ribbons are substantially higher than those of the annealed ribbon melt-spun atΔT+=60 K.Among these annealed ribbons,the magnetic properties of the ribbon melt-spun atΔT+=90 K achieve maximum values,and its optimum magnetic properties are Hci=521.57 kA/m,Br=0.75 T,(BH)max=66.31 kJ/m 3 and Mr/M s=0.67.
作者
赵丽
潘晶
刘新才
杨梦琳
董鸣月
凌安
ZHAO Li;PAN Jing;LIU Xincai;YANG Menglin;DONG Mingyue;LING An(Faculty of Materials Science and Chemical Engineering,Ningbo University,Ningbo 315211,China)
出处
《功能材料》
EI
CAS
CSCD
北大核心
2018年第4期4046-4053,共8页
Journal of Functional Materials
基金
国家自然科学基金资助项目(51174121
51274125)
浙江省重点科技创新团队资助项目(2012R10016-08)
关键词
熔体过热度
形核过冷度
非晶形成能力
微观组织演化
磁性能
melt overheating
nucleation undercooling degree
glass formability
microstructure evolution
magnetic properties
