Abstract
In this study the L1 2 gamma prime phase (based on Ni 3 Al) has been highly alloyed with Cr, Co, W, and Ta in order to examine the effects on strengthening and thermal stability. The order-disorder transition temperature of gamma prime is decreased with higher alloying content. Thermodynamic calculations show that the ordering enthalpy decreases as the entropy term increases. Conversely, the hardness can be 1.5 times higher comparing to that of a conventional Ni-based superalloy. This indicates that the strengthening effect of designing a gamma prime composition toward higher entropy is significant, due to greater lattice distortion and higher anti-phase boundary energy of gamma prime.