Fundamental Understanding of the Intrinsic Ductility in Nickel-Base L12 Type Alloys.
Annual rept. 15 Feb 86-14 Feb 87,
PRATT AND WHITNEY WEST PALM BEACH FL GOVERNMENT PRODUCTS DIV
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To study the effects of alloying on ductility of Ni3A1 alloys, three series of alloys were formulated and produced as single crystals. The alloying additions selected include tantalum, tin and titanium which tend to destabilize the L12 lattice toward different derivative structures by changing the relative magnitudes of the planar fault energies. These alloying effects are being studied in terms of the structural configuration of dislocations produced, deformation behavior and the resulting ductility of the alloys. A major effort in the first year program was to grow single crystals of the selected alloys and some technical difficulties were encountered. Single crystals of all the selected alloys with the exception of a tin-containing alloy have now been successfully grown. Tensile testing has been completed for a tantalum and a titanium-containing alloy. Relative to the binary alloy, the alloying additions were found to significantly increase the critical resolved shear strength CRSS for octahedral slip system without substantially affecting the CRSS for the cube slip system. Keywords Nickel aluminide, Single crystals, Ductility, Strength, Nickel alloys.
- Properties of Metals and Alloys