Microstructural investigation of Nd-rich phase in sintered Nd-Fe-B magnets through electron microsco

• 作 者: 付新 韩小磊 杜志伟 冯海波 李岩峰
• 机 构: National Center of Analysis and Testing for Non-ferrous Metals & Electronic Materials, General Resea
• 出 处: Journal of Rare Earths
• 发表日期: 2004年期
• 关键词: sintered tetragonal SAED dispersive hundreds attributed grains sizes inhomogeneo

The distribution, morphologies and structures of intergranular Nd-rich phase in sintered Nd-Fe-B magnets were studied through electron microscopy. Backscattered electron (BSE) imaging revealed that Nd-rich particles with various morphologies and sizes were randomly distributed at the grain boundaries and the triple junctions of the tetragonal Nd2Fe14B matrix. Through selected area electron diffraction (SAED) analysis under a systematic tilting condition, most intergranular Nd-rich phase particles, with sizes ranging from hundreds of nanometres to several micrometres, were identified as face-centred cubic (FCC) structure. Such particles possessed several approximate orientation relationships with their adjacent Nd2Fe14B matrix grains, such as (002) Nd2Fe14B//(200) FCC_Nd-rich [120] Nd2Fe14B//[001] FCC_Nd-rich , (002) Nd2Fe14B//( 220 ) FCC_Nd-rich [110] Nd2Fe14B//[112] FCC_Nd-rich , as well as (011) Nd2Fe14B//(131) FCC_Nd-rich [111] Nd2Fe14B//[114] FCC_Nd-rich , which could be attributed to minimising interfacial energy. The combination of highresolution electron microscopy with energy-dispersive X-ray spectroscopy revealed the internal inhomogeneous nature of Nd-rich phases. The large lattice distortion and nanoscale-ordered structures within a single Nd-rich grain were observed.

The distribution, morphologies and structures of intergranular Nd-rich phase in sintered Nd-Fe-B magnets were studied through electron microscopy. and the triple junctions of the tetragonal Nd2Fe14B matrix. Through selected area electron diffraction (SAED) analysis under a systematic tilting condition, most intergranular Nd-rich phase particles, with sizes ranging from hundreds of nanometres to several micrometres, were identified as face-centered Such particles possessed several approximate orientation relationships with their adjacent Nd2Fe14B matrix grains, such as (002) Nd2Fe14B // (200) FCC_Nd- rich [120] Nd2Fe14B // [001] FCC_Nd- rich, (002) Nd2Fe14B // (220) FCC_Nd-rich [110] Nd2Fe14B // [112] FCC_Nd-rich, as well as (011) Nd2Fe14B // (131) FCC_Nd- rich [111] Nd2Fe14B // [114] FCC_Nd- rich, which could be attributed The combination of highresolution electron microscopy with energy-dispersive X-ray spectroscopy revealed the internal inhomogeneous nature of Nd-rich phases. The large lattice distortion and nanoscale-ordered structures within a single Nd-rich grain were observed.