【作者】 王海波；

【导师】 张博；

【作者基本信息】 合肥工业大学 ， 材料工程（专业学位）， 2015， 硕士

【摘要】 非晶态合金,亦称金属玻璃,具有长程无序、短程有序的原子结构特点,表现出优异的物理性能和化学性能。其中,电磁特性优异的铁基非晶合金,作为铁芯材料以广泛应用于电子元器件及电力设备变压器的生产和制造。铁基非晶合金制造成本低廉、应用过程能耗极低,是一种极具开发价值与应用前景的绿色节能材料。但是,经过几十年的科研探索,铁基非晶合金的玻璃形成形成能力仍然较低,非晶合金的最大尺寸只有十几毫米,而性能优异并能在实现生产中广泛应用的铁基非晶合金商业产品几乎全部为薄带状,且厚度仅限几十微米。因此,打破铁基非晶合金玻璃形成能力较低与产品形貌单一的瓶颈,探索并开发出成本低廉、玻璃形成能力较高和性能优异的铁基非晶合金,对于理解非晶合金的形成机理,加速铁基非晶合金产品的商品化和拓宽其应用领域具有重要意义。本文通过合理的成分设计,使用了大量廉价工业纯原料,通过廉价海绵钛的使用取代了(Fe71.2B24Y4.8)96Nb4初始合金中贵重金属Nb元素,成功开发出成分为(Fe71.2B24Y4.8)96Nb4-xTix(x=0,1,2,3,4)的新型铁基金属玻璃体系,在降低初始合金制备成本的同时明显提高了合金的玻璃形成能力。通过分析研究得到以下结论：成分为(Fe71.2B24Y4.8)96Nb4-xTix(x=0,1,2,3,4)的铁基非晶合金热力学性能分析表明,Ti元素的添加可以明显提高体系的玻璃形成能力。当Ti元素含量从从0 at.%增加到4 at.%时,完全非晶态样品的玻璃化转变温度Tg,晶化温度Tx均呈现出先上升后下降的趋势,且当Ti元素含量x=2 at.%时,名义成分为(Fe71.2B24Y4.8)96NB2Ti2的合金表现出最大玻璃形成能力,成功制备出最大直径为6mm的完全非晶态圆柱状铸态样品,同时具有体系中最大的过冷液相区宽度ΔTx=103K,最大的约化玻璃化转变温度Trg=0.608以及最大的参数7=0.423。随着该合金体系中Ti元素含量的不断增加,合金的完全非晶态样品的饱和磁化强度Ms整体呈现下降趋势,样品的矫顽力Hc受到外界因素影响较多而变化更为复杂。实验数据表明,该体系非晶态合金的饱和磁化强度Ms和矫顽力Hc与合金的玻璃形成能力GFA之间并无直接联系。同时我们发现,使用不同工艺制备的名义成分为(Fe71.2B24Y4.8)96Nb2Ti2的铁基非晶薄带(冷却速率高)和块体金属玻璃(冷却速率低),受冷却速率影响合金内部形成了不同的磁畴结构,薄带状非晶合金的饱和磁化强度较块体略大且矫顽力大幅降低,表现出更为优异的软磁性能。另外,压缩力学性能测发现,Fe-B-Y-Nb-Ti五元金属玻璃体系表现出较高的压缩断裂强度σf≥ 3000MPa,且(Fe71.2B24Y4.8)96Nb2Ti2金属玻璃压缩断裂强度达3400MPa,显微硬度值Hv0.1=1208。上述结果表明,本文开发出的新型铁基块体金属玻璃成本低廉、物理性能优异,具有很好的商业应用前景。更多还原

【Abstract】 Because of the structure characteristics of long-range disorder and short-range order, amorphous alloys that are also called metallic glasses exhibit excellent physical and chemical properties.Among these systems, Fe-base amorphous alloys have been widely used in the field of production and manufacturing of electronic components and power equipment transformers for its outstanding electromagnetic characteristics. Fe-based amorphous alloys are capable to be a new type of energy-saving and environmentally-friendly materials with its own advantages on low energy consumption and low cost in application process.However, by decades of scientific researches and explorations, Glass forming ability of Fe-based amorphous alloys are still lower than other systems, and can only get the samples with maximum size only a few millimeters. At the same time, almost all Fe-based amorphous alloys that have been widely applied as commercial products with excellent performances are manufacture into ribbons and the thickness of obtained products are limited in several micrometers. Therefore, by exploring and developing new Fe-based amorphous alloys with low cost, high glass forming ability and excellent performance to break the bottleneck in low glass forming ability and monosized product morphology, is significant for us to understand the formation mechanism of amorphous alloy, accelerate the commercialization of the Fe-base amorphous alloys products and broaden its application field.In this paper, we developed quinary Fe-B-Y-Nb-Ti BMGs by using high-purity elements and low-purity industrial raw materials, including a Fe-B alloy and sponge titanium. By using cheap titanium sponge replaced the original precious metal element Nb in the alloy, we have successfully developed a new type Fe-based bulk metallic glasses with nominal compositions of (Fe71.2B24Y4.8)96Nb4-xTix (x=0,1,2,3,4), that not only reduce the cost of initial alloys but also improve the glass forming ability of alloys obviously. By analyzing the experimental data we get the following conclusions:The STA thermal scans of as-cast (Fe71.2B24Y4.8)96Nb4-xTix (x=0,1,2,3,4) amorphous samples showed that addition of Ti element can obviously improve the glass forming ability of alloys. when the content of Ti element increases from 0 at.% to 4 at.%, the glass transition temperature (Tg) and the onset temperature of the crystallization peaks (Tx) of the samples with completely amorphous structure monotonically increased first and then gradually decreased. When the content of Ti element x=2 at.%, the nominal composition of (Fe71.2B24Y4.8)96Nb2Ti2 alloy exhibited the best glass forming ability (Dmax=6 mm), which showed the largest supercooled liquid regions Δ Tx=103 K, the biggest reduced glass transition temperature Trg=0.608 and parameters y=0.423.The saturation magnetization (Ms) of samples decreases gradually with Ti substitution increasing, and coercivity (Hc) fluctuated seriously caused by the influence of various external factors. The results showed that there is no direct relation between glass forming ability and saturation magnetization or coercivity..In addition, compared with its rod shape glassy state (low cooling rate), the (Fe71.2B24Y4.8)96Nb2Ti2 ribbon samples (high cooling rate) presented more excellent soft magnetic properties with higher saturation magnetization and lower coercivity, which is expected from the resulted different magnetic domain structures in the ribbon and bulk samples caused by different fabrication processes that corresponding differing cooling rates. Finally, We also investigated the mechanical properties of the new quinary Fe-B-Y-Nb-Ti BMGs system, which exhibits high compressive fracture strength σf≥ 3000MPa, and further measure of compressive fracture strength of (Fe71.2B24Y4.8)96Nb2Ti2 BMGs even reached up to 3400 MPa with Vickers microhardness Hv0.1=1208. These results demonstrate that the present Fe-based bulk metallic glasses might be a potential candidate for commercial applications with low cost and good performance.更多还原