HIGH STRAIN RATE DEFORMATION MECHANISMS IN CVD TUNGSTEN AND RHENIUM

CHEMICALLY VAPOR DEPOSITED (CVD) TUNGSTEN IS POTENTIALLY A COSTEFFECTIVE MATERIAL FOR HIGH STRAIN RATE APPLICATIONS. THE EFFECTS OF PROCESS VARIABLES ON THE MECHANICAL PROPERTIES OF CURRENTLY AVAILABLE CVD TUNGSTEN ARE NOT UNDERSTOOD SUFFICIENTLY FOR ITS PROPERTIES TO BE OPTIMIZED FOR A VARIETY OF HIGH STRAIN RATE APPLICATIONS. IN THIS PHASE I PROGRAM, ULTRAMET PROPOSES TO INVESTIGATE THE EFFECTS OF PROCESS VARIABLES ON THE CHEMISTRY, MICROSTRUCTURE, AND HIGH STRAIN RATE MECHANICAL PROPERTIES OF CVD TUNGSTEN AND RHENIUM. A UNIQUE DOUBLE-PURIFICATION METHOD WILL BE USED TO CONTROL ANION IMPURITIES IN TUNGSTEN TO LEVELS PREVIOUSLY UNATTAINABLE. CVD RHENIUM IS OF INTEREST BECAUSE IT EXHIBITS DUCTILITY AT ROOM TEMPERATURE AND AT LOW STRAIN RATES, IN CONTRAST TO RECENT EXPERIENCE WITH TUNGSTEN. IT WILL THUS BE AN EXCELLENT BASELINE COMPARISON MATERIAL.