gamma ' Formation and morphology evolution in the undercooled structure ofDD3 Single crystal superalloy

An investigation of the gamma' formation and its morphology evolution in th e bulk undercooled DD3 single crystal superalloy is performed. The applicat ion of a molten salt denucleating technique combined with thermal cycle ena bles such investigation over a wide range of undercooling up to 210 K. The microstructure formation has been respectively discussed with respect to un dercooling, nucleation and solute segregation during solidification and pos t-solidification, by employing the classical nucleation theory. Furthermore , TEM and SEM technique are adopted to reveal the gamma' microscopy and to illustrate other factors correlated to the gamma' precipitation. It is foun d that the size, fraction, and distribution of precipitated gamma' in as-so lidified DD3 single crystal superalloy are all influenced by melt undercool ing. (C) 2001 Kluwer Academic Publishers.