【作者】 李雷鸣；

【导师】 徐锦锋； 翟秋亚；

【作者基本信息】 西安理工大学 ， 材料科学与工程， 2008， 硕士

【摘要】 根据快速凝固原理,自行设计了一套单辊急冷快速凝固实验装置,制备出了非晶薄带,研究了Zr基非晶合金的快速凝固特征。通过将金属熔体能量方程及Navier-Stokes方程相耦合,理论计算了液态合金的冷却速率;利用Takeuchi修正模型估算了该合金形成非晶的临界冷却速率。借助XRD、TEM、DSC分析技术,研究了Zr基非晶合金的结构特征,并对合金的电阻率、抗拉强度和伸长率等性能进行了量化表征,进而探索了冷却速率、组织形态与合金性能的相关规律。在快速凝固过程中,液池温度在垂直辊面的高度方向上的变化,比与辊面相切的水平方向上的温度变化显著,且熔体自上而下、自左至右的流动过程中,在高度约25μm处流速的大小和方向均发生变化,水平流速迅速增大,高度方向的流速急剧减小,两者在x＞0.6mm时趋于稳定。合金的冷却速率随辊速的增大而增大。制备出的Zr_xAl_yNi_zCU_100-x-y-z（x=45,55,65;y=8,10,12;z=3,5,7）合金薄带均为非晶态结构。Zr₅₅Al₁₂Ni₃Cu₃₀合金的玻璃形成能力最好,其临界冷却速率较低,只有4.7K/s,而Zr₄₅Al₁₂Ni₇Cu₃₆合金的玻璃形成能力最差,其临界冷却速率较高,达610K/s。正交试验结果表明,成分为Zr₄₅Al₁₂Ni₇Cu₃₆,辊速控制在约40m/s所获得的非晶合金薄带具有最理想的性能。冷却速率对非晶合金薄带性能具有显著的影响。随冷却速率的增大,Zr₄₅Al_xNi_x-5Cu_60-2x（x=8,10,12）合金的抗拉强度升高,伸长率则有所降低,电阻率逐渐增大。更多还原

【Abstract】 In the paper, a set of single roller device has been manufactured according to rapid solidification principle, which is applied to produce the amorphous alloys and the rapid solidification characteristics of Zr-based alloy have been studied. By coupling of the energy equation and the Navier-Stokes equation, the cooling rate of the alloy is calculated theoretically. Meanwhile, using Takeuchi modified model, the critical cooling rate of forming amorphous alloy is also estimated. The structural characteristics of Zr-based amorphous alloy have been studied by using XRD, TEM and DSC analysis techniques, and the electrical resistivity, tensile strength and elongation of Zr-based amorphous alloys are quantificationally characterized. The relations of cooling rate and microstructure morphology with alloy properties are also investigated.During rapid solidification, the temperature of puddle changes more significant along the vertical direction than that in the horizontal direction. The alloy melt changes its flow rate and velocity direction rapidly at about 250μm height. The horizontal flow velocity increases rapidly, but the vertical flow velocity decreases sharply, both of them tend to be stable when x>0.6mm. The cooling rate of the alloy increases with the increase of the wheel velocity. The alloy foils prepared with the compositions of Zr_xAl_yNi_zCu_{（100-x-y-z）}（x=45,55,65; y=8,10,12; z=3, 5, 7） are all amorphous. The glass forming ability of Zr₅₅Al₁₂Ni₃Cu₃₀ alloy is the best, whoes critical cooling rate is merely 4.7K/s, much lower than others, whereas, the critical cooling rate of Zr₄₅Al₁₂Ni₇Cu₃₆ is much higher to 610K/s.The results of the orthogonal test indicate that: the Zr₄₅Al₁₂Ni₇Cu₃₆ amorphous alloy foils obtained has the best properties when the wheel velocity is controlled at 40m/s.The cooling rate has significant influence on the properties of the amorphous alloy. With the increase of the cooling rate, the tensile strength and electrical resistivity of Zr₄₅Al_xNi_x-5Cu_60-2x（x=8, 10, 12） amorphous alloy increase, but the elongation decreases.更多还原