【作者】 甘章华；

【导师】 肖建中；

【作者基本信息】 华中科技大学 ， 材料学， 2004， 博士

【摘要】 块体非晶、纳米晶磁性材料因其呈现的优异磁性能,已成为新型磁性材料研究的一个重要方向。本文概述了国内外关于非晶、纳米晶磁性材料研究现状及发展,通过大量的设计和实验,研究了铁基块体非晶、纳米晶合金的成分设计、制备工艺、微观结构、各种性能以及它们之间的关系。 针对制备铁基块体非晶合金所需高纯 FeP 合金原料难以获得的问题,提出了一种用纯 Fe 和纯 P 合成高纯 FeP 合金的新工艺:低温扩散+快速加热。用该工艺可顺利合成 Fe89.87P10.13wt%、Ni81P19at%,、Fe68.4S31.6wt%、Ni77S23wt%、Co88.5P11.5wt%等共晶合金。 本文提出了制备块体非晶合金的复合工艺:助熔剂净化+铜模铸造。自行设计了一系列铜模,可以简单方便地制备多个系列合金,包括柱状、片状、筒状以及圆环状等各种形状试样的块体非晶材料。 采用助熔剂净化和铜模铸造相结合的工艺,用工业纯原料制备出块体非晶合金（Fe40Ni40P14B6） 100-xGax（x=4⁶）。样品为直径 3mm 的圆柱体或宽 6mm、厚 1mm 的片材,长度都在 10 至 15mm 左右。实验表明,适量 Ga 元素的加入提高 Fe-Ni-P-B合金的非晶形成能力。Ga 提高合金非晶形成能力的主要原因是 Ga 对合金中的Fe3Ni3B、（Fe,Ni）23B6 等难熔相的产生有抑制作用。 实验表明,对有较强非晶形成能力的合金（Fe40Ni40P14B6） 100-xGax（x=4⁶）,用适量的 In 取代 Ga 对合金的非晶形成能力影响不大。而金属 In 的价格远比金属 Ga低,因而在不影响性能的前提下,用 In 取代 Ga 具有工程意义。 用助熔剂净化+铜模铸造复合工艺,制备了块体非晶合金（Fe40Co40P14B6）95Ga5。试样为厚 0.8mm、宽约 6mm,长约 20mm 的片材和直径 2mm,长约 20mm 的圆柱体。 对六种成分铁基合金的非晶形成能力进行了对比,认为六种铁基合金非晶形成能力的顺序为:Fe65.5Cr4Mo4Ga4P12C5B5.5>Fe72Al5Ga2P11B4C5Si1^{Fe40Ni40P14B6}96Ga4^{Fe40Ni40P14B6}94Ga4In2>（Fe40Co40P14B6）95Ga5>>（Fe40Ni40Mo4B16） 95Ga5。 研究了 Fe40Ni40P14B6 合金的深过冷凝固组织,发现 Fe40Ni40P14B6 合金经助熔剂净化后,在缓慢冷却条件下进行深过冷凝固时,随过冷度增大,显微组织由棒状共晶转变为几百纳米大小的网状调幅结构;在冷却速率较大的凝固条件下,将得到枝晶状组织。且随净化程度不同而导致凝固前深过冷能力的不同,快速凝固组织呈现含有三次枝晶的树枝晶、只含有二次枝晶的树枝晶、胞状晶的变化趋势,且胞状晶 I<WP=4>的间距 λ 非常小,呈现为纳米纤维状结构。研究了块体非晶合金（Fe40Ni40P14B6）96Ga4在 Tg至 Tx附近进行退火时的非晶晶化组织。发现块体非晶合金（Fe40Ni40P14B6）96Ga4在 Tg至 Tx之间进行长时间退火时,试样将发生晶化。在不同退火条件下,块体非晶合金（Fe40Ni40P14B6）96Ga4晶化后将得到由放射状纳米晶组成的球状晶团和由网状调幅结构断裂而成的纳米等轴晶等晶粒形貌。当退火温度为 710K,退火时间为 60min 时,获得了较为均匀的纳米晶组织,晶粒直径约为 8nm。更多还原

【Abstract】 Bulk amorphous and nanocrystalline magnetic material has become very much apioneering research issue because of its excellent magnetism properties. In this paper, thehistory of bulk amorphous and nanocrystalline magnetic material and the researchprogress is reviewed. The chemical composition of the Fe-based bulkamorphous/nanocrystalline alloy, its manufacture technique, microstructure, propertiesand the relationship between them are investigated. It’s difficult to obtain the high purity FeP alloy that used as the raw material for thepreparation of Fe-based bulk amorphous. To solve the problem, a new technique: diffusionin low temperature + rapidly heating, is presented to synthesis the high purity FeP alloywith pure iron powder and pure phosphor powder. With the similar technique, a series ofeutectic alloys such as Fe89.87P10.13wt%、Ni81P19at%,、Fe68.4S31.6wt%、Ni77S23wt%、Co88.5P11.5wt% have been synthesized successfully. In this thesis a new compound technique: flux-melting + copper casting, is presentedto prepare bulk amorphous alloy from industrial raw materials. A series of copper mouldshave been designed. With the different copper mould, bulk amorphous alloys can beprepared easily with different shapes such as rod, plate, cylinder and ring. Bulk amorphous alloys （Fe40Ni40P14B6） 100-xGax（x=4⁶）have been prepared in theform of 3-mm-diam rods or 1-mm-thick plates by utilizing industrial raw materials. Theglass synthesis consists of flux-melting and copper casting. Differential scanningcalorimetry and X-ray diffraction show that amorphous alloys can formed for x=4-6. Theproperties measurements indicate that the amorphous alloys possess strong corrosionresistance and excellent soft magnetic properties. The microhardnessvalue of theamorphous alloy is lower than that of the crystalline alloy with the same composition. Ithas been demonstrated that Ga addition can be greatly helpful to increase theglass-forming ability of Fe40Ni40P14B. The main reason of increasing the glass-formingability should be that the Ga addition restrains the crystallization of the Fe3Ni3B、（Fe,Ni）23B6. It has been demonstrated that In addition can replace part of Ga addition, which haslittle influence on the glass-forming ability of （Fe40Ni40P14B6） 100-xGax（x=4⁶）. However,The price of pure indium is far lower than that of pure gallium. Therefore, It is veryimportant that gallium can replace by indium. III<WP=6>Bulk amorphous alloy （Fe40Co40P14B6）95Ga5 has been prepared in the form of Φ2×20mm rods and 0.8×6×20 plates by industrial raw material.. The glass synthesis consistsof flux-melting and copper casting. The glass-forming ability of six kinds of Fe-based alloys has been compared.According the glass-forming ability, the order may beFe65.5Cr4Mo4Ga4P12C5B5.5>Fe72Al5Ga2P11B4C5Si1^{Fe40Ni40P14B6}96Ga4^{Fe40Ni40P14B6}94（Ga4In2）>（Fe40Co40P14B6）95Ga5>>（Fe40Ni40Mo4B16） 95Ga5. The high undercooling solidification microstructure of Fe40Ni40P14B6 alloy has beenresearched. It has been found that the samples have different microstructures if thesolidificotion conditoin is different. After fluxing, if the cooling rate is low, the specimenwith high undercooling is occupied by subnetwork microstructure. If the cooling rate ishigh, the eutectic microstructure varies from dendrite containing tertiary dendrite arms,dendrite containing secondary dendrite arms to nanofiber with the alloy’s undercoolingincreasing. Bulk nanocrystalline alloy （Fe40Ni40P14B6）96Ga4 has been prepared by suitablycontrolled annealing treatment of the bulk amorphous alloy. When the samples anneal inthe temperature between Tg and Tx for 60min, the crystallization occures. Under thedifferent annealing condition, the microstructure presents two kinds of morphologys:crystal reunion composed of nanocrystal and equiaxed grain. When the annealingtemperature is 710K, the annealing time is 60min,更多还原