【作者】 王永田；

【导师】 王万录； 汪卫华；

【作者基本信息】 重庆大学 ， 凝聚态物理， 2005， 硕士

【摘要】 本论文对两种新型稀土基大块金属玻璃及其相关纳米晶材料进行了研究。对Pr₆₀Al₁₀Ni₁₀Cu₂₀ 大块金属玻璃进行Fe 掺杂,制备出微观结构和性能可以调控的大块纳米晶合金,并分析了其结构和磁性随Fe 含量的变化关系。另外还对新型Tb 基大块金属玻璃及Tb 纳米晶阵列进行了研究。用铜模吸铸方法获得的Pr₆₀Cu₂₀Ni₁₀Al₁₀大块金属玻璃样品的最大直径为5毫米,这种新的Pr 基大块金属玻璃具有明显的玻璃转变和稳定的过冷液相区,其玻璃转变温度很低,在升温速率为10 K/min 时为409 K,常温下呈现顺磁性。本文提出了一种通过对大块稀土基金属玻璃进行Fe 掺杂,制备出微观结构和性能具有可调控性的大块纳米晶合金的方法。重点报道和研究了对Pr₆₀Al₁₀Ni₁₀Cu₂₀ 大块金属玻璃进行Fe 掺杂制备出Pr-Al-Ni-Cu-Fe 系大块纳米晶合金,并对这一体系的非晶形成能力,微观结构以及磁学和力学等性能进行了分析研究。结果表明Pr 基合金逐步从玻璃状态,转变为非晶与纳米晶的复合状态,最后成为纳米晶合金,Pr 基合金的磁学和力学性能也相应地发生了变化。并讨论了掺杂对微结构和性能影响,纳米晶的产生机制以及纳米晶结构和性能之间的关系。本文还报道了新型Tb 基大块金属玻璃及Tb 纳米晶阵列,并对制备方法及其结构进行了详细的研究。用铜模吸铸方法获得的Tb₃₆Y₂₀Co₂₀Al₂₄大块金属玻璃的最大直径为5 毫米,这种新的Tb 基大块金属玻璃具有较高的玻璃转变温度和弹性模量。以铜辊甩带法制备出大面积的高度定向生长的二维Tb 纳米晶薄膜,该纳米晶粒生长在非晶基底上,高度为15³0 nm,宽度为10²0 nm,并对纳米晶的形成机理进行了讨论,提出了一种新而简单的制备定向生长的纳米晶薄膜或阵列的方法。更多还原

【Abstract】 This work focuses on analysis and studying of the two newly discovered RE-based bulk metallic glasses （BMGs） and related nanocrystalline materials. We report that the formation of bulk nanocrystalline alloys with tunable microstructure and properties based on the Pr₆₀Al₁₀Ni₁₀Cu₂₀ BMG-forming alloy by doping Fe. In addition, the newly developed Tb-based BMGs and Tb nanocrystalline array have also been studied. The critical section thickness of the Pr₆₀Cu₂₀Ni₁₀Al₁₀ composition is 5 mm in diameter for die cast, which exhibits a distinct glass transition and a wide supercooled liquid region （SLR）. The glass transition temperature is 409 K when the scanning rate is 10K/min, and it exhibits paramagnetic in room temperature. Our work firstly presents a simple approach to obtain the bulk nanocrystalline material with controllable microstructure, by doping RE-based BMGs with Fe. We report that the formation of Pr-Al-Ni-Cu-Fe bulk nanocrystalline alloy based on the Pr₆₀Al₁₀Ni₁₀Cu₂₀ BMG-forming alloy by doping Fe,including its glass forming ability （GFA）,microstructure, magnetic and mechanical properties. By varying the content of Fe, the microstructure of the Pr-based alloy changes progressively from full glassy state to composite with nanocrystalline particles embedded in the glassy matrix, and finally into nano-structured state accompanying with the gradual magnetic and mechanical property changes. The role of the addition in the control of microstructure and property, the mechanism for the nanocrystalline formation induced by addition, and the relation between the microstructure and properties are discussed. The newly developed Tb-based BMGs and nanocrystalline array have been studied, including the preparation and microstructure. The critical section thickness of the Tb_<sub>36Y₂₀Co₂₀Al₂₄ composition is 5 mm in diameter for die cast, which exhibits higher glass transition temperature and elastic moduli. A two-dimensional （2D） thin film composed of Tb nanocrystals with uniform orientations is fabricated from Tb₆₅Fe₂₅Al₁₀ alloy melt upon quenching. The Tb nanocrystals with vertical height of 15-30 nm and lateral width of 10-20 nm are assembled into the nanocrystalline array on amorphous substrate. The formation mechanism for the Tb nanocrystals is discussed. The formation method may provide a new and flexible alternative to fabricate nanostructured film or array.更多还原