【摘 要】
：
The solidification microstructure and fractal characteristics of the solid-liquid interfaces of Inconel718, under different cooling rates during directional sol
【机 构】
：
High Temperature Materials Research Laboratories,School of Materials,National Key Laboratory of Soli
论文部分内容阅读
The solidification microstructure and fractal characteristics of the solid-liquid interfaces of Inconel718, under different cooling rates during directional solidification, ware investigated by using SEM. Results showed that 5 μm/s was the cellular-dendrite transient rate. The prime dendrite arm spacing (PDAS) was measured by Image Tool and it decreased with the cooling rate increased. The fractal dimension of the interfaces was calculated and it changes from 1.204310 to 1.517265 with the withdrawal rate ranging from 10 to 100 μm/s. The physical significance of the fractal dimension was analyzed by using fractal theory. It was found that the fractal dimension of the dendrites can be used to describe the solidification microstructure and parameters at low cooling rate, but both the fractal dimension and the dendrite arm spacing are needed in order to integrally describe the evaluation of the solidification microstructure completely.
其他文献
利用运动学模型,研究了弯曲急流控制参数为定常和发生周期扰动时的流体质点运动轨迹以及混沌现象的产生机制.发现弯曲急流控制参数为定常时,流体质点的运动为规则的周期运动;
目的 研究HER - 2 /neu(c -erbB - 2 )在卵巢上皮性肿瘤中的表达及意义。方法 收集 10 6例卵巢上皮性肿瘤 (恶性 5 4便 ,交界性 33例 ,良性 19例 )及临床资料。按国际妇产
安徽铜陵狮子山铜-金矿床有两种与岩浆热液有关的矿化类型:隐爆角砾岩型和矽卡岩型.矿床中的成矿流体至少发生过四次沸腾.第一次发生于隐爆角砾岩阶段,熔体-流体包裹体温度高于600℃,盐度超过42％（质量百分比,下同）NaClequiv,代表了一种富水残浆;第二次发生于矽卡岩化过程中,流体温度为422℃～472℃,平均458℃,盐度为10.2％～45.1％NaClequiv;第三次发生于主成矿阶段,即石
西藏北部双湖地区海相侏罗纪磁性地层采样剖面包括菊花山下侏罗统剖面和那底岗日中、上侏罗统剖面,采集样品共1231件.磁性地层采样工作是在实测地层(岩石地层和生物地层)剖面
了解海岸沙坝的内部结构对于动态地恢复海岸沙坝与海平面变化的相互关系具有重要的意义,探地雷达(GPR)为海岸沙坝的研究提供了一种快速、经济和高分辨率的地球物理方法;探地
对双星定位系统在中低轨卫星轨道确定中的应用做了详细的分析,给出了在该系统的测量模式下中低轨卫星定轨的几种方法.通过对这些方法进行的大量模拟计算和分析,结果表明作为
Effect of different noise reduction measures for diesel engines was evaluated based on hierarchy diagnosis. The hierarchy diagnosis chart and hierarchy judgment
用X射线光电子能谱研究了无定形氢氧化铁吸附水溶液中镉离子的机理 ,结果表明 ,吸附镉离子后的氢氧化铁中的氧和铁都有电子的向内转移 ,说明吸附过程是化学吸附 ,吸附时氢氧
A new reliability allocation model has been built for engine system, which is a repairable system, and consists of a large number of mechanical components. The
标准文献因其特殊性,文后参考文献的著录规则也应该突出重点,删减一些不必要的著录内容。
Due to its particularity, the standard documents should also stress the key