Microstructure evolution and coercivity mechanism of hydrogenation-disproportionation-desorption-recombination(HDDR) treated Nd-Fe-B strip cast alloys  

作　　者：Bin Ma Xiaoqian Bao Aizhi Sun Jiheng Li Xuexu Gao 

机构地区：[1]State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing,Beijing 100083,China [2]Institute for Advanced Materials and Technology,University of Science and Technology Beijing,Beijing 100083,China

出　　处：《Journal of Rare Earths》2022年第5期792-799,I0005,共9页稀土学报（英文版）

基　　金：Project supported by the State Key Laboratory for Advanced Metals and Materials(2019Z-14)。

摘　　要：In this paper,we systematically investigated the microstructure evolution and coercivity mechanism of hydrogenation-disproportionation-desorption-recombination(HDDR)treated Nd-Fe-B strip cast alloys by transmission electron microscopy(TEM)and three-dimensional atom probe(3 DAP)analyses.The rodlike NdH_(2+x) phases with diameters of 10-20 nm are embedded intoα-Fe matrix,which hereditarily leads to textured grains in HDDR alloy.The migration of NdH_(2+x) from Nd-rich region toα-Fe matrix during hydrogen absorption process contributes to the uniform redistribution of Nd-rich phases after HDDR treatment The HDDR alloy with single domain grain sizes of 200-300 nm exhibits relatively low coercivity of 1.01 T that arises from pinning magnetic domain motion.The weak c-axis orientation of HDDR alloy results in a lower reverse magnetic field(coercivity)to reduce remanence to 0.Moreover,the direct contact of Nd_(2)Fe_(14)B grains and the high concentration of ferromagnetic elements(Fe content≈66.06 at%,Co content≈0.91 at%)in Nd-rich grain boundary layer lead to strong magnetostatic coupling effect among Nd_(2) Fe_(14)B grains.The nano-sized a-Fe inside Nd_(2) Fe_(14)B matrix makes the magnetization reversal easily and decreases the coercivity of HDDR alloy.

关 键 词：Nd-Fe-B strip Cast HDDR treatmemt Microstructure evolution Coercivity mechanism Three-dimensional atom probe Rare earths 

分 类 号：TG143[一般工业技术—材料科学与工程]