The present paper describes the effect of alloy composition,homogenization and dehy-drogenization procedures on magnetic properties of NdFeB type of HDDR powders and the bonded magnet.The results showed that the powde...The present paper describes the effect of alloy composition,homogenization and dehy-drogenization procedures on magnetic properties of NdFeB type of HDDR powders and the bonded magnet.The results showed that the powders prepared by HDDR process possesses useful magnetic proper- ties and a better thermal stability than the sintered NdFeB magnet does.展开更多
The recombination stage of the HDDR process of Sm 2Fe 17 compound was investigated by X ray AFM and VSM. Hydrogen treatment at 750℃ for 3 h makes the Sm 2Fe 17 compound disproportionate completely into ...The recombination stage of the HDDR process of Sm 2Fe 17 compound was investigated by X ray AFM and VSM. Hydrogen treatment at 750℃ for 3 h makes the Sm 2Fe 17 compound disproportionate completely into α Fe and SmH 2 with grain sizes ranging from a few to 20 nm. These grains aggregate into short rod like aggregations. Because of the very short mutual diffusion distances between Sm and Fe atoms, α Fe and SmH 2 recombine into Sm 2Fe 17 very quickly. For only 1 min of dehydrogenation, a small amount of Sm 2Fe 17 compound is formed, and the recombination reaction is completed in 5～10 min.展开更多
The demagnetization process and the coercivity mechanism for amsotropic HDDR Nd(Fe,Co)B bonded magnets were studied by comparing the dependence of coercivity on the alignment field applied while the powders were press...The demagnetization process and the coercivity mechanism for amsotropic HDDR Nd(Fe,Co)B bonded magnets were studied by comparing the dependence of coercivity on the alignment field applied while the powders were pressed. The results showed that both the remanence and the coercivity of magnet increased with increasing alignment field. The demagnetization process of the magnet can be classified as the nucleation process inside the grains and the domain-wall motion between the grains. The combined effect of two processes determines the coercivity of HDDR NdFeB bonded magnets.展开更多
文摘The present paper describes the effect of alloy composition,homogenization and dehy-drogenization procedures on magnetic properties of NdFeB type of HDDR powders and the bonded magnet.The results showed that the powders prepared by HDDR process possesses useful magnetic proper- ties and a better thermal stability than the sintered NdFeB magnet does.
文摘The recombination stage of the HDDR process of Sm 2Fe 17 compound was investigated by X ray AFM and VSM. Hydrogen treatment at 750℃ for 3 h makes the Sm 2Fe 17 compound disproportionate completely into α Fe and SmH 2 with grain sizes ranging from a few to 20 nm. These grains aggregate into short rod like aggregations. Because of the very short mutual diffusion distances between Sm and Fe atoms, α Fe and SmH 2 recombine into Sm 2Fe 17 very quickly. For only 1 min of dehydrogenation, a small amount of Sm 2Fe 17 compound is formed, and the recombination reaction is completed in 5～10 min.
文摘The demagnetization process and the coercivity mechanism for amsotropic HDDR Nd(Fe,Co)B bonded magnets were studied by comparing the dependence of coercivity on the alignment field applied while the powders were pressed. The results showed that both the remanence and the coercivity of magnet increased with increasing alignment field. The demagnetization process of the magnet can be classified as the nucleation process inside the grains and the domain-wall motion between the grains. The combined effect of two processes determines the coercivity of HDDR NdFeB bonded magnets.
