Anisotropic magnets were obtained by hot deformation with the partial crystallized precursor prepared via spark-plasma sintering （SPS）. Amorphous powders with the nominal composition of Nd_28.72Fe_balCo_5.66 Ga_0.59...Anisotropic magnets were obtained by hot deformation with the partial crystallized precursor prepared via spark-plasma sintering （SPS）. Amorphous powders with the nominal composition of Nd_28.72Fe_balCo_5.66 Ga_0.59B_0.92 （wt%） were used as the starting material. The results show that the amorphous powders would suffer varying degrees of crystallization even below the crystal- lization point during the SPS process under high pressure. And the pre-crystallized grains in precursors have great impacts on the microstructure and magnetic properties of the hot-deformed magnets. The final obtained anisotropic magnets exhibit homogeneous microstructure consisting of well-aligned and platelet-shaped Nd_2Fe_14B grains without abnormal growth. It can be found that a reasonable pro- portion of pre-crystallized gains could promote the pref- erential orientation in the magnet, leading to the achievement of optimal magnetic properties among the magnets with identical composition and best magnetic performance is achieved in the magnet hot deformed from the 490 ℃ high-pressure hot-pressed precursor.展开更多
Nanoporous Ag-Pt bi-metallic alloy was fabricated by free dealloying of amorphous Ag-based precursor with the nominal composition of Ag38.25Pt0.5Cu38.75Si22.5.The noble Ag and Pt were left after the less noble Cu and ...Nanoporous Ag-Pt bi-metallic alloy was fabricated by free dealloying of amorphous Ag-based precursor with the nominal composition of Ag38.25Pt0.5Cu38.75Si22.5.The noble Ag and Pt were left after the less noble Cu and Si dissolved in a certain acid solution.Bi-continuous nanoporous microstructure was formed with asymmetric ligaments and pores with typically 30-200 nm in width.The trace addition of Pt has refined the grains of the ligaments to the average size of less than 20 nm in the substrate and induced the formation of rods with nanopores.The morphologies of the rods were observed by scanning electron microscopy(SEM)and transmission electron microscopy(TEM)both in the form of clusters and as scattered individuals with characteristic length of several micrometers and diameter of tens of nanometers.The grains sizes in the rods were finer than those in the ligaments.The good mechanical integrity might be due to the combination of continuous ligaments and clusters of rods.展开更多
基金supported by the National Natural Science Foundation of China (No. 51171122)the Sichuan Province Science and Technology Support Program (Nos. 2014GZ0090 and 2016GZ0262)
文摘Anisotropic magnets were obtained by hot deformation with the partial crystallized precursor prepared via spark-plasma sintering （SPS）. Amorphous powders with the nominal composition of Nd_28.72Fe_balCo_5.66 Ga_0.59B_0.92 （wt%） were used as the starting material. The results show that the amorphous powders would suffer varying degrees of crystallization even below the crystal- lization point during the SPS process under high pressure. And the pre-crystallized grains in precursors have great impacts on the microstructure and magnetic properties of the hot-deformed magnets. The final obtained anisotropic magnets exhibit homogeneous microstructure consisting of well-aligned and platelet-shaped Nd_2Fe_14B grains without abnormal growth. It can be found that a reasonable pro- portion of pre-crystallized gains could promote the pref- erential orientation in the magnet, leading to the achievement of optimal magnetic properties among the magnets with identical composition and best magnetic performance is achieved in the magnet hot deformed from the 490 ℃ high-pressure hot-pressed precursor.
基金financially supported by the China Postdoctoral Science Foundation(No.2015M570964)the National Key Research and Development Program of China(No.2017YFB0304504)。
文摘Nanoporous Ag-Pt bi-metallic alloy was fabricated by free dealloying of amorphous Ag-based precursor with the nominal composition of Ag38.25Pt0.5Cu38.75Si22.5.The noble Ag and Pt were left after the less noble Cu and Si dissolved in a certain acid solution.Bi-continuous nanoporous microstructure was formed with asymmetric ligaments and pores with typically 30-200 nm in width.The trace addition of Pt has refined the grains of the ligaments to the average size of less than 20 nm in the substrate and induced the formation of rods with nanopores.The morphologies of the rods were observed by scanning electron microscopy(SEM)and transmission electron microscopy(TEM)both in the form of clusters and as scattered individuals with characteristic length of several micrometers and diameter of tens of nanometers.The grains sizes in the rods were finer than those in the ligaments.The good mechanical integrity might be due to the combination of continuous ligaments and clusters of rods.
