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 2016-11-15 Cooperative journals: 《金属学报》
Abstract：采用增强过滤电弧离子镀技术在单晶Si基片上制备了3组不同过渡金属的氮化物薄膜MNx(M=Ti,Zr,Hf)。用FESEM,GIXRD,XPS,NanoIndenter等方法对MNx薄膜的形貌、厚度、相结构、成分、元素的化学态、残余应力、弹性模量和硬度等进行了表征。结果表明，3组MNx薄膜均在较宽的成分范围内表现为fcc单相结构，并且同组薄膜间的择优取向、厚度、晶粒尺寸和残余应力等均基本保持一致；特别是3组薄膜的硬度和弹性模量均随氮成分x的变化而变化，并且都在x=0.82附近出现性能峰值。分析表明，MNx薄膜与成分相关的性能增强，其决定性因素不在于介观尺度的晶粒细化、择优取向及内应力等，而是取决于原子尺度的化学键合及电子结构等因素。
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%。
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