APPLICATION OF d-ELECTRON ALLOY DESIGN THEORY TO DEVELOPMENT OF HOT CORROSION RESISTANT Ni-BASE SINGLE CRYSTAL SUPERALLOYS——I Characterization of Phase Stability

A study of the hot corrosion behaviour of the alloy system Ni－16Cr－9A1－2W－1Mo－4Co－Ti－Ta－Nb (in at. －%) selected by the d－electrons alloy design theory was conducted. At the same time, four experimental compositions were selected in the optimum compositional ranges to characterize the single crystal growth behaviour and properties.Finally, the compositions of an alloy with the desired balance of the comprehensive properties was determined as Ni－16Cr－gA1－2W－1Mo－4Co－3.125Ti－0.875Ta(at. － %). This alloy satisfies the alloy design requirements fairly good, i.c., it shows the hot corrosion resistance at the same or higher level of IN 738 LC, while the service temperature capability 70－90℃ higher than IN 738 LC. The stress rupture strength of this alloy reaches the level of the single crystal alloy CMSX-2 which contains much less Cr content, and is the highest among the current hot corrosion resistant nickel-base superalloys. The results of this study show the effectiveness and feasibility of applications of the d-electrons alloy design concept to the design and development of hot corrosion resistant nickel-base superalloys.ZHANG Jishan, associate professor,(Department of Materials Science and Engineering,Univeristy of Science and Technology Beijing, Beijing 100083)