Develop, Fabricate and Test High Strength Directionally Solidified Eutectic Alloys.

摘要

A directionally solidified eutectic alloy was synthesized based on the Ni-Cr eutectic,but containing in addition to nickel, 37.0 w/o Cr, 18.0 w/o W, 10.0 w/o Co and 0.1 w/o Al. This eutectic,while not of optimized composition,shows superior oxidation-hot corrosion resistance over existing eutectic alloys and some nickel base superalloys,and as a system holds promise of a strength advantage over the superalloys in the temperature region of 2000F and above. Use of the Ni3Cb reinforced eutectics has been made more practical by demonstration of superplastic bonding of a superalloy to the gamma prime-delta (Ni-23.1Cb-4.4Al) eutectic,such as would be done in forming a turbine blade root. The effect of particle impingement on this eutectic and the gamma-gamma prime-delta (Ni-20.7Cb-3.2Al) eutectic was studied and showed that while some cracking can be expected with high impact energies,microstructural changes are limited to the immediate area of the impact. Heat treatment was shown to increase the room temperature and intermediate temperature strength of both delta reinforced eutectics,but has little effect at 2000F. (Author)