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磁性纳米复合材料一般是由非磁性绝缘体和分散在它内部的磁性纳米颗粒(10～100nm)组成的。纳米颗粒的小尺寸效应和与基体的高浓度界面以及基体的绝缘性,使得磁性纳米复合材料表现出许多优异的物理和化学性能,在高密度信息存储、磁致冷等领域有着重要的应用价值。由于Fe-N合金在耐磨、抗氧化和抗腐蚀等方面优于纯铁,且具有较高的平均原子磁矩(如Fe_4N为2.21μ_B,Fe_3N为2.01μ_B),尤其是近2年发现α″-Fe_(16)N_2的巨磁性现象(平均原子磁矩达3.2～2.8μ_B),使得Fe-N合金及其复合材料的研究工作引起了广大材料学家和物理学家的高度重视和极大的兴趣。最近几年,人们通常以N_2,NH_3和NH_3/H_2气体为氮源,利用气相沉积、磁溅射并结合热处理的方法,制备各种结构的Fe-N合金薄膜和Fe-N合金纳米复合材料膜。然而,利用其他技术和材料制备Fe-N合金及其复合材料尚无报道。在本实验中,我们将采用一种新的实验方法,即以六方氮化硼(hBN)为氮源,利用高能球磨技术制备Fe-N/BN磁性纳米复合材料。在此方法中,Fe-N合金在Fe与hBN的球磨过程中原位生成,并均匀分布在绝缘BN基体上与BN基结合牢固且界面清洁。晶粒尺寸和相成分可通过球磨参量控制,经热烧结可制成块状材料,具有实用价值。
Magnetic nanocomposites are generally composed of a non-magnetic insulator and magnetic nanoparticles dispersed within it (10-100 nm). The small size effect of nano-particles and the high concentration interface with the matrix and the insulation of the matrix make the magnetic nanocomposites show many excellent physical and chemical properties and have important application value in the fields of high-density information storage and magnetic refrigeration . Since Fe-N alloy is superior to pure iron in terms of wear resistance, oxidation resistance and corrosion resistance, and has a high average atomic magnetic moment (such as 2.21μ_B for Fe_4N and 2.01μ_B for Fe_3N), α "-Fe_ (16) N_2 giant magnetic phenomenon (average atomic magnetic moment of 3.2 ~ 2.8μ_B), making the Fe-N alloy and its composites research has attracted the attention of many materials scientists and physicists, and pole In recent years, people usually use N_2, NH_3 and NH_3 / H_2 gas as nitrogen source to prepare various structures of Fe-N alloy thin film and Fe-N by vapor deposition, magnetic sputtering and heat treatment, However, there are no reports on the preparation of Fe-N alloy and its composites by other techniques and materials.In this experiment, we will adopt a new experimental method, namely, hexagonal boron nitride (hBN) As a nitrogen source, Fe-N / BN magnetic nanocomposites were prepared by high-energy ball milling technique. In this method, Fe-N alloy was generated in situ during the ball milling of Fe and hBN and uniformly distributed on the BN substrate Combined with a solid and clean interface. Grain size and phase composition can be controlled by milling parameters, heat Junction can be made of bulk material, having a practical value.