粉末冶金工艺对纯铁软磁材料性能的影响

利用粉末冶金技术制备纯铁软磁材料，在不同温度和压力下将不同粒径铁粉压制成生坯，并在保护气氛下进行烧结。结果表明:不同粒径铁粉混合有助于压坯密度的增加，适宜的压制温度可以有效地促进粉末流动，避免大尺寸孔洞的形成，优化组织。140℃、800 MPa温压条件下雾化铁粉压坯密度最高可达7.35 g·cm-3。对比常温压制，温压压坯烧结后孔洞分布均匀。烧结体密度随温度的升高而上升，雾化铁粉压坯在1250℃烧结后密度最高可达7.47 g·cm-3。在一定范围内，软磁材料磁性能与密度成正比，混粉压制试样的密度接近理论值，但在混合铁粉中，较细的铁粉夹杂于粗粉中，阻碍磁畴壁移动，造成饱和磁化强度（M_s）偏小、矫顽力（H_c）偏大的现象，M_s为205.51 emu·g-1，Hc为7.9780 Oe。

Effect of powder metallurgy technology on properties of pure iron soft magnetic material

Powder metallurgy technology was proposed to prepare the pure iron soft magnetic material. The green of iron powders in different size distribution was compacted at different temperatures and pressures, and then was sintered in protective atmosphere. The results show that the appropriate size proportion of iron powders is helpful to increase compaction density. The suitable pressing temperature can effectively promote the powder flowability, avoid the formation of large-sized pores, and finally optimize the microstructures of iron powder green. The highest compaction density of atomized iron powders can achieve 7.35 g·cm-3 in the warm compaction condition of at 140℃ and 800 MPa. Compared with the normal temperature compaction, the pore distribution of sintered body prepared by warm compaction is uniform. The density of sintered body increases with the increase of temperature. After sintered at 1250℃, the highest density of atomized iron powder compaction can reach 7.47 g·cm-3. The magnetic properties of soft magnetic material are proportional to the density. The density compacted by iron powders in different size distribution is close to the theoretical. But in the mixed iron powders, the fine iron powders are mixed in the coarse powders, which hinder the movement of the magnetic domain wall, resulting in the phenomenon that the saturation permeability (M_s) is smaller (205.51 emu·g-1) and the coercivity (H_c) is higher (7.9780 Oe).