Specific Heat and Thermal Transport Measurements of Reactive Metallic Alloys by Noncontact Calorimetry in Reduced Gravity

Experimental concepts, application, and recent results of noncontact calorim- etry inculding ac-specific heat and thermal transport property measurement of reactive metallic specimens are described. The method is based on induction heating in an electromagnetic levitation device. Experiments have been per- formed in reduced gravity onboard Spacelab. A heat flow model is discussed regarding conditions for precise specific heat determination from the tempera- ture response to modulated heating power input as well as determination of thermal transport properties from the transient temperature response. Modula- tion techniques were developed for application in the metastable regime of the undercooled melt, where processing time is a critical issue. Results to be dis- cussed include the total hemispherical emissivity of a bulk metallic glass-forming alloy revealing effects of surface segregation, thermal conductivity measurements, and application of ac calorimetry in the two-phase region.