Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： The formation of amorphous phase has been investigated in U-Co system over a wide range of compositions, namely, UxCo100-x (x=50~87.5) by mean of melt-spinning. Phase identification for the arc-melted ingots and rapidly quenched alloys, and the thermal stability of the amorphous phases thus formed have been examined by XRD and DSC, respectively. The component phases in the ingot alloys were structurally the same as those presented in U-Co phase diagram, but were associated with a certain compositional metastability. Rapid quenching experiment revealed that the ease of formation of amorphous phase occurred within the composition range of 58.5≤x≤78, and amorphous phase was most readily formed in the vicinity of U66.7Co33.3 composition. The dynamical crystallization temperatures of the amorphous phases were determined to be 534~550 K at a DSC heating rate of 20 K/min, and the highest reduced crystallization temperature (relative to the liquidus temperature) as calculated to be 0.535, and moreover, the exothermal enthalpies of crystallization were determined to be in a range of 4.8~8.5 kJ/mol. Upon room temperature electrochemical polarization in a 50×10- 6 Cl- electrolyte, these amorphous alloys exhibited corrosion potentials as high as about -50 mV, being much more positive than that of depleted uranium. In these amorphous alloys, it has also been found that the rust resistance performance appears to be parallel to the ease of amorphous phase formation.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： The structural and compositional features of amorphous alloys can be described by cluster- plusglue atom model, which is an effective method for the composition design of amorphous alloys. In the Fe-B binary system, Fe2B phase is an intermetallic phase related to Fe83B17 eutectic point. Under the framework of the highest radial number density and isolation principle, the local structure of Fe2B phase is characterized by a B-centered Archimedean octahedral antiprism [B-B2Fe8] atomic cluster. Combined with the electron consistence criterion, the [B-B2Fe8]Fe (here the center and shell atoms are separated by a hyphen, a cluster is enclosed in square brackets, the glue atom is out square brackets) is then determined as an ideal cluster formula for Fe-B binary amorphous. To further enhance the glass-forming ability (GFA) of the alloy, the center B and shell Fe atoms in [B-B2Fe8]Fe are replaced with Si and Ta, respectively, due to their large negative enthalpy of mixing between Si-Fe and (B, Si)-Ta atomic pairs, and Fe-B-Si-Ta quaternary composition series, namely [Si-B2Fe8- xTax]Fe, are thus derived. The experimental results reveal that the bulk amorphous alloys with a diameter of 1.0 mm can be achieved for [Si-B2Fe8- xTax]Fe (x=0.4~0.7) compositions. Among them, [Si-B2Fe7.4Ta0.6]Fe (i.e. Fe70B16.67Si8.33Ta5, atomic fraction, %) is the best glass former, its glass transition temperature Tg, supercooled liquid region ΔTx and the reduced glass transition temperatures Trg are 856 K, 33 K and 0.584, respectively. The Vickers hardness, saturation magnetization and coercivity of the [Si-B2Fe7.6Ta0.4]Fe (i.e. Fe71.67B16.67Si8.33Ta3.33) amorphous alloy are measured to be 1117 HV, 1.37 T, and 3.0 A/m, respectively.
Subjects: Materials Science >> Materials Science (General) submitted time 2017-03-31 Cooperative journals: 《金属学报》
Abstract：研究了熔体快淬Fe55-xCoxPt15B30 (x = 0~45，原子分数，%)合金热处理前后的组织结构和磁性能。结果表明，添加Co可提高Fe55Pt15B30合金的非晶形成能力，使x = 15~45的快淬合金形成非晶态。经适当热处理后，合金中形成了由有序面心四方结构的永磁(Fe, Co)-Pt(L10)相和软磁(Fe, Co)2B相及(Fe, Co)B相组成的纳米复相组织，而显示出永磁性；添加Co合金的组织得到明显细化，x = 15~45合金平均晶粒尺寸均约为18 nm；其中x = 15合金具有最佳的永磁性能，磁能积达到94.4 kJ/m3。合金的矫顽力随Co含量的增加而增大，在x = 30时达到最大值413.7 kA/m后，随Co含量的进一步增加而减小。通过解析合金的组织结构，解释了Co含量变化对磁性能的影响机理。
Subjects: Materials Science >> Materials Science (General) submitted time 2016-11-15 Cooperative journals: 《金属学报》
Abstract：利用“团簇加连接原子”模型设计和优化具有高形成能力的Fe-B-Si-Nb块体非晶合金。以源于Fe-B二元共晶相的Fe2B局域结构为基础，结合电子浓度判据，构建Fe-B二元理想非晶团簇式[B-B2Fe8]Fe；考虑到原子间混合焓的大小，选择Si和Nb原子分别替代[B-B2Fe8]团簇的中心原子B和壳层原子Fe，得到[Si-B2Fe8-xNbx]Fe系列四元非晶成分。结果表明，[Si-B2Fe8-xNbx]Fe团簇式在x = 0.2 ~ 1.2成分处均可形成块体非晶合金，其中在x = 0.4~ 0.5的成分区间内均可形成临界尺寸为2.5 mm的块体非晶合金。考虑到原子半径的大小，鉴于增加Nb的同时降低Si的含量可维持[Si-B2Fe7.6Nb0.4]Fe非晶团簇结构的拓扑密堆性，由此得到另一系列[(Si1-yBy)-B2Fe8-xNbx]Fe团簇式成分。结果表明，在(x = 0.5, y = 0.05) ~ (x = 0.9, y = 0.25)成分区间内均可通过Cu模铸造法获得直径为2.5 mm的块体非晶。新设计获得的Fe-B-Si-Nb块体非晶合金具有优良的室温软磁性能和力学性能，其中[Si-B2Fe8-xNbx]Fe（x = 0.2 ~ 0.6）非晶合金的饱和磁化强度为1.14 ~ 1.46 T，矫顽力为1.9 ~ 6.7 A/m；[(Si0.95B0.05)-B2Fe7.5Nb0.5]Fe块体非晶合金的室温压缩断裂强度达4220 MPa，塑性形变约为0.5%。
Subjects: Materials Science >> Materials Science (General) submitted time 2016-11-10 Cooperative journals: 《金属学报》
Abstract：将U-Co二元系中的富U合金UxCo100-x（x = 50~87.5，原子分数，下同）作为研究对象，采用电弧熔炼与甩带方法制备它们的母合金锭与薄带样品，通过X 射线衍射和差示扫描量热分析研究合金样品的相组成与稳定性，同时采用动电位极化方法研究非晶合金的耐腐蚀性能。结果表明，条带非晶形成的成分区间为58.5? x ?78，其最佳成分出现在U66.7Co33.3附近；在20 K/min加热速率下，U-Co非晶的晶化温度位于534~550 K之间，晶化放热焓为4.8~7.9 kJ/mol，约化晶化温度Trx值最高达0.535；在50 x 10-6 Cl-溶液中，U-Co非晶合金的腐蚀电位大都接近-50 mV，其抗腐蚀能力显著优于贫铀，且U-Co非晶耐腐蚀性与其形成能力显示出正相关性。
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