DESIGN AND DEVELOPMENT OF HOT CORROSION-RESISTANT NICKEL-BASE SINGLE-CRYSTAL SUPERALLOYS BY THE D-ELECTRONS ALLOY DESIGN THEORY .1. CHARACTERIZATION OF THE PHASE-STABILITY

As the first step to design and develop the new hot corrosion-resistan t nickel-base single-crystal superalloys by the d-electrons alloy desi gn theory (or the New PHACOMP), an evaluation of the phase stability o f the modified hot corrosion-resistant IN738LC nickel-base superalloys Cr-9.5Al-4.0Ti-8.0-Co-0.55Nb-0.06Zr-0.05B-0.47C-(0 approximately 3)Ta -(0 approximately 3)W-(0 approximately 3)Mo (in atomic percent)) was c onducted with the alloy design theory. The critical conditions for sup pressing the precipitation of the brittle sigma phase can be described by the electronic parameters MdtBAR less-than-or-equal-to 0.991 and M dgammaBAR less-than-or-equal-to 0.93 which can be applied to the d-ele ctrons alloy design of hot corrosion resistant nickel-base superalloys with high Cr contents.