Phase change and heat treatment of U-Si alloys

A series of uranium alloys varying in silicon content 0.5∼1.0 a/0 were studied. The tendency of the β or γ phase uranium to retain upon quenching was examined as a function of silicon content. The β phase can be retained at room temperature, while the retention of the γ phase could not be observed at all. TTT diagrams and microstructures after isothermal transformation were studied, and the existence of two modes in the β-to-α transformation is clarified. The M_s temperature of the martensitic β-to-α transformation, which increases with decreasing silicon content, is determined and it is clarified that the suitable grainrefinement is attained by the isothermal transformation in the temperature region slightly higher than M_s temperature. (author)