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采用FMI-I-600R-C型真空熔炼速凝炉生产(Nd-Pr)Fe B速凝薄片,系统研究了速凝薄片厚度对其微观结构的影响。结果表明:厚度的差异造成了速凝薄片微观结构及相组成的不同。薄片厚度为0.2~0.3 mm时,从贴辊面到自由面的完整片状晶生长良好,富Nd-Pr相沿主相均匀分布,无α-Fe;厚度为0.3~0.4 mm时,完整片状晶的体积分数降低;厚度为0.5 mm以上的薄片在自由面会析出α-Fe,在靠近贴辊面一侧出现细晶区;随着厚度的增加,析出的α-Fe相逐渐增多,在α-Fe相的析出区域出现了团块状的富Nd-Pr相。薄片厚度为0.2~0.4 mm时,(001)晶面的衍射峰较强,Nd2Fe14B主相晶粒具有明显的c轴择优取向;随着厚度的增加,(001)晶面的衍射峰强度逐渐减弱,主相晶粒沿c轴择优生长的趋势减弱。因此,在批量生产(Nd-Pr)Fe B速凝薄片的过程中,控制合理的薄片厚度是生产优质速凝薄片的关键。
The F-I-600R-C type vacuum smelting quick-setting coagulation furnace was used to produce (Nd-Pr) Fe B quick-setting flakes. The influence of the thickness of the quick-setting flakes on the microstructure was investigated systematically. The results show that the difference of thickness causes the difference of the microstructure and phase composition of the quick-setting sheet. When the thickness of the sheet is 0.2-0.3 mm, the complete lamellar crystal growth from the roll surface to the free surface is good. The Nd-Pr-rich phase is uniformly distributed along the main phase with no α-Fe. When the thickness is 0.3-0.4 mm, The volume fraction of the crystal decreases; α-Fe precipitates on the free surface when the thickness is more than 0.5 mm, and the fine grain area appears on the side close to the surface of the roller. As the thickness increases, the precipitated α-Fe phase gradually increases, The precipitated region of the -Fe phase appears as a bulk Nd-Pr rich phase. The diffraction peak of the (001) crystal plane is strong when the thickness of the thin film is 0.2-0.4 mm, and the c-axis preferred orientation of the crystal grain of the Nd2Fe14B main phase is obvious. With the increase of the thickness, the diffraction peak intensity of the (001) crystal plane is gradually weakened , The main phase along the c-axis preferred growth of grain weakened. Therefore, it is the key to produce high-quality quick-setting flakes that a reasonable thickness of the flakes should be controlled during mass production of (Nd-Pr) Fe B flakes.