Abstract
In present study, a Si-bearing directionally solidified (DS) Ni-base superalloy (KC-5) has been developed based on the composition of CM247LC with Ti, Mo and Si additions. High temperature creep and oxidation properties of KC-5 have been evaluated. Strain-ageing method coupled with EPMA analysis has been conducted to determine the elemental partitionings between gamma and gamma-prime phases, and high temperature XRD analysis has been performed to determine the lattice misfit between gamma and gamma-prime phases. Experimental results indicate that KC-5 exhibits large lattice misfit toward negative; this has led to early formation of raft and dramatically decrease the creep strain rate. Si partitions toward gamma phase and promotes the formation of continuous Al 2 O 3 on the surface of KC-5 after high temperature oxidation. However, there are debits associated with reduction in heat treatment window and phase instability in this newly designed DS alloy. © 2013 Elsevier B.V. All rights reserved.