Bradshaw R C, Warren M E, Rogers J R, Rathz T J, Gangopadhyay A K, Kelton K F, Hyers R W
Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Ann N Y Acad Sci. 2006 Sep;1077:63-74. doi: 10.1196/annals.1362.058.
High-temperature measurement and study of reactive materials can be difficult with conventional processing methods because contamination from the measuring apparatus and container walls can adversely affect measurements. Containerless processing techniques can be employed to isolate samples from their environment, reducing contamination. Benefits of containerless processing include reduction in heterogeneous nucleation sites, which in turn delays the onset of solidification and allows the study of meta-stable undercooled phases. However, property measurements must use noncontact methods as well. Fortunately, several optical-based methods have been developed and successfully employed to measure thermophysical properties, including surface tension, viscosity, density, and thermal expansion. Combining these techniques with the electrostatic levitator (ESL) located at the NASA Marshall Space Flight Center (MSFC) has resulted in an excellent facility to perform containerless material studies which support microgravity flight projects. Currently, studies of the thermophysical properties of liquid quasi-crystal forming and related alloys ranging from superheated to deeply undercooled states are being done with this facility in support of the NASA-funded flight project Quasi-crystalline Undercooled Alloys for Space Investigation (QUASI). While the primary purpose of these measurements is to support planned flight experiments, they are also a desirable resource for future manufacturing considerations and for fundamental insight in the physics of icosahedral ordering in liquids and solids. Presented here is an overview of the contactless measuring methods for surface tension, viscosity, density, and thermal expansion applied to Zr54Ti8Cu20Al10Ni8, for the superheated and meta-stable undercooled liquid phases, in support of QUASI.
采用传统加工方法对活性材料进行高温测量和研究可能会很困难，因为测量仪器和容器壁的污染会对测量产生不利影响。可采用无容器加工技术将样品与周围环境隔离开来，减少污染。无容器加工的好处包括减少异质形核位点，这反过来会延迟凝固的开始，并允许对亚稳态过冷相进行研究。然而，性能测量也必须使用非接触方法。幸运的是，已经开发出了几种基于光学的方法，并成功地用于测量热物理性质，包括表面张力、粘度、密度和热膨胀。将这些技术与位于美国国家航空航天局马歇尔太空飞行中心（MSFC）的静电悬浮器（ESL）相结合，形成了一个用于进行无容器材料研究的出色设施，以支持微重力飞行项目。目前，正在利用该设施对从过热到深度过冷状态的液态准晶形成及相关合金的热物理性质进行研究，以支持美国国家航空航天局资助的飞行项目“用于太空研究的准晶过冷合金”（QUASI）。虽然这些测量的主要目的是支持计划中的飞行实验，但它们也是未来制造考虑以及对液体和固体中二十面体有序物理的基本洞察的理想资源。本文概述了应用于Zr54Ti8Cu20Al10Ni8的过热和亚稳态过冷液相的表面张力、粘度、密度和热膨胀的非接触测量方法,以支持QUASI项目。
