Abstract
New nickel-based superalloys for industrial turbines with high Cr content were designed with the aid of the d-electrons concept. This concept has been developed on the basis of the molecular orbital calculations of the electronic structures of Ni alloys. Two electronic parameters are important in this concept. One is the bond order between an alloying element and nickel atoms, Bo, and the other is the d-orbital energy level of alloying element, Md. Employing these parameters, singlecrystal(SC) superalloys were designed with the compositions : Ni-(9.5-12.O)Al-(16.5-18.O)Cr(0.6-2.4)Ti-(0.3- l.QTa-(0-OS)Nb-(0.9-1.6)W-( 1.2-l .8 )Mo-(O-0.25)Re [mol%]. A similar method was also employed for the design of directionally solidified(DS) alloys. Namely, alloy compositions without any grainboundary strengthening elements were firstly designed and then a small amount of Hf was simply added into them to strengthen the grain-boundaries. The creep properties and hot corrosion resistance were evaluated experimentally for these SC and DS alloys. As a result, the SC alloys were found to be superior in the creep rupture life to a reference alloy, SC-16, while keeping hot corrosion resistance as high as SC-16 and IN738LC. The DS alloys also exhibited better creep properties than several alloys so far developed.
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call