纳米复合材料退火时间对交换耦合与微结构的影响研究

需积分: 5 23 浏览量更新于2024-08-12 收藏 609KB PDF 举报

"Effect of annealing time on exchange coupling interactions and microstructure of nanocomposite Pr7.5Dy1Fe71Co15Nb1B4.5 ribbons (2007年) - 论文 - 工程技术" 这篇论文探讨了退火时间对纳米复合材料Pr7.5Dy1Fe71Co15Nb1B4.5带材的交换耦合相互作用和微观结构的影响。研究采用了振动样品磁强计（VSM）、X射线衍射（XRD）以及高分辨率透射电子显微镜（HRTEM）等方法进行系统研究。退火处理是材料加工中的关键步骤，它能改变材料的内部结构，从而影响其性能。在这项研究中，作者发现退火时间对Pr7.5Dy1Fe71Co15Nb1B4.5纳米复合材料的磁性能具有显著影响。当在700°C下退火15分钟后，材料获得了最大值的退火交换耦合强度（Jr）、内禀矫顽力（Hci）和最大磁能积(BH)max。这些性能的优化可能归因于在这个退火条件下形成了Pr2(Fe,Co)14B、α-(Fe,Co)和微量的Pr2(Fe,Co)17相的复杂结构。尽管随着退火时间的进一步增加，Jr、Hci和(BH)max会逐渐降低，但研究指出，在较宽的退火时间范围内，仍可以保持相对较高的Jr和Hci以及(BH)max。这表明，通过调整退火条件，可以有效地控制这种纳米复合材料的磁性特性，以适应不同的应用需求。交换耦合是硬磁和软磁颗粒之间的一种现象，其中相邻颗粒间的磁矩通过交换相互作用而保持对齐。这种耦合在磁记录和磁性存储介质中尤为重要，因为它决定了材料的磁稳定性。在本研究的材料中，通过磁力显微镜（MFM）观察到了由强交换耦合产生的交互域，这为理解材料的磁性行为提供了直接的视觉证据。微观结构的演变也受到退火时间的影响。XRD分析揭示了材料相的形成和变化，而HRTEM则提供了亚微米级别的细节，帮助研究者深入理解了不同相之间的界面以及颗粒尺寸和分布如何影响磁性能。这篇论文揭示了退火时间对纳米复合磁性材料Pr7.5Dy1Fe71Co15Nb1B4.5的重要作用，尤其是在优化其磁性能方面。这些发现对于设计和开发高性能磁性材料，特别是在工程技术领域，如磁存储、磁传感器和磁性器件等方面，具有重要的理论和实际意义。

Effect of annealing time on exchange coupling interactions and microstructure of

nanocomposite Pr

7.5

4.5

ribbons

Xiaoqian Bao, Yi Qiao,

Maocai Zhang, Jie Zhu, and Shouzeng Zhou

State Key Laboratory for Advanced Metals and Materials, University of Science and Technology

Beijing, Beijing 100083, China

Abstract: The influence of annealing time on magnetic properties and microstructure of

nanocomposite Pr

7.5

4.5

ribbons was systematically investigated by the methods of

vibrating sample magnetometer (VSM), X-ray diffraction (XRD) and high resolution transmission

electron microscopy (HRTEM). Interaction domains derived from strong exchange coupling

interactions between hard and soft magnetic grains were imaged using magnetic force microscopy

(MFM). Maximum J

, H

and (BH)

max

values were obtained in the ribbons annealed at 700C for

15 min, which were composed of Pr

(Fe, Co)

B, -(Fe, Co), and slight Pr

(Fe, Co)

phases.

Although J

, H

, and (BH)

max

decreased gradually with further increase of annealing time, it is

emphasized that comparatively high J

and H

and (BH)

max

were obtained in a wide annealing time

period of 15 to 360 min. The shape of initial magnetization curves and hysteresis

loops change as a

function of annealing time, indicating different magnetization reversal routes, which can be fully

explained by the corresponding microstructure.

Key words: nanocomposite magnets; exchange coupling interaction; microstructure; magnetization

reversal

[This work was financially supported by the National Natural Science Foundation of China

(No.10074005).]

1. Introduction

Nanocomposite permanent magnets, which are also called exchange spring magnets, have

attracted considerable attention as a probable new generation of permanent magnets with a potential

theoretical (BH)

max

in excess of 10

J/m

and with lesser cost [1-4]. Production of melt-spun

precursor materials with an amorphous or nanoscaled structure and precise thermal treatment are the

two key processes which determine the magnetic performance of nanocomposite materials.

However, the processing window for producing remanence-enhanced rare-earth RFeB melt-spun

ribbons with optimum magnetic properties by direct quenching to a nanocrystalline structure is

narrow and the properties within a batch vary due to the differences in ribbon thickness [5-8]. One

way to overcome this is to produce amorphous material by overquenching, followed by annealing to

obtain the desired microstructure [9-12]. Furthermore, for R

B/-Fe type nanocomposites, the

size and volume fraction of -Fe and R

B can be manipulated by thermal processing. In this

article, a systematic study has been performed on the effect of annealing time on the microstructure

and magnetic properties of Pr

7.5

4.5

ribbons.

2. Experimental procedures

The alloy with a nominal composition of Pr

7.5

4.5

was prepared by induction

melting the pure constituent elements under high-purity atmosphere. The ingots were melted 3-4

times to ensure homogeneity. The overquenched ribbons were produced by melt spinning in an

argon atmosphere onto a copper roll rotating at circumferential speed, V

=30 m/s. These amorphous

flakes with the thickness of about 20 m were then annealed at 700C for 2-360 min under the

vacuum of 2×10

3

Pa to crystallize and develop a fine nanoscaled microstructure and optimize the

coercivity.

The ribbons were examined by XRD analysis, using Cu K



radiation, prior to annealing and at

下载后可阅读完整内容，剩余4页未读，立即下载

weixin_38735804

粉丝: 5
资源: 966

纳米复合材料退火时间对交换耦合与微结构的影响研究

Effect of annealing temperature on shape memory effect of cold-rolled Ti-16Nb alloy

Effect of annealing on the damage threshold and optical properties of HfO

Effect of annealing on the characteristics of Au/Ni50Fe50 bilayer films grown on glass (2007年)

Influence of annealing temperature on microstructure and H2 sensing properties of Pd-doped SnO2 thin films

The Effect of Thermal Annealing on the Optical Properties of Graphene Oxide

Effect of Size and Annealing on the Giant Magnetic Impendence Properties of FeCoSiB Ribbon

论文研究-The effect of RTP pre-annealing on the precipitation behavior and electrical property of copper in CZ silicon.pdf

Post annealing effect on optical and electrical properties of Ga-doped Zn1-xCdxO thin films

Influence of annealing temperature on the performance of Ge film and photon-counting imaging system

Influence of annealing on the structural and electrical transport properties of Bi0.5Sb1.5Te3.0 thin films deposited by co-sputtering

最新资源