HIGH TEMPERATURE DEFORMATION BEHAVIOR OF SOLID AND SEMI-SOLID ALLOY 718

摘要

The mechanical response of alloy 718 with various microstructures in the solid and semi-solid state has been characterized. The experimental results presented for the lower temperature solid state defor- mation are in good agreement with published literature values and extend the experimental range to higher temperatures and lower strain rates. When dendrites were aligned along the compression axis, the direc- tionally solidified materials exhibited an activation energy for plastic flow consistent with the activation energy for creep and self diffusion in nickel, even at temperatures within the mushy zone. However, samples containing non-aligned grains in the semi-solid state exhibited a greater dependence of defor- mation with temperature, this was associated with lubricated flow of the grains due to the intergranular liquid in the mushy zone.