Kinetic study of aging in a uranium-titanium eutectoid alloy using thermoelectric power measurement

Considerable attention has been given to the study of microstructure evolution and mechanical properties of dilute U-Ti alloys. A typical procedure of heat treatment of the eutectoid uranium-titanium alloy consists of solution treatment in the γ phase, obtaining of soft α^′ martensitic metastable structure by water quenching to room temperature and precipitation hardening by aging at 300-550°C. Depending on employed temperature and time the aging results in GP zone formation through the precipitation reaction α^′→α+δ. The δ phase is a hexagonal U₂Ti intermetallic compound, responsible for the significant increase in the level of the micro-strain in the metastable α^′ matrix. Thermoelectric power (TEP) measurements have recently gained a growing attention for the characterization of metallurgical properties in steels and other alloys. These measurements, which are based on the Seebeck effect, are sensitive to changes in the electronic structure of the material as result of various metallurgical processes. In the current research, TEP measurement technique was applied as a non destructive assessment technique to characterize the aging kinetics of the quenched uranium-titanium binary alloy. Good correlation has been found between measured TEP, micro-strain evolution, as obtained by using XRD, and hardness values at different heat treatment stages. A reasonable explanation of the correlation between the crystallography changes, micro-strain, TEP measurements and properties is presented.