High temperature deformation behavior of solid and semi-solid alloy 718

The mechanical response of alloy 718 with various microstructures in the so lid and semi-solid state has been characterized. The experimental results p resented for the lower temperature solid state deformation are in good agre ement with published literature values and extend the experimental range to higher temperatures and lower strain rates. When dendrites were aligned al ong the compression axis, the directionally solidified materials exhibited an activation energy for plastic how consistent with the activation energy for creep and self-diffusion in nickel, even at temperatures within the mus hy zone. However, samples containing non-aligned grains in the semi-solid s tate exhibited a greater dependence of deformation with temperature; this w as associated with lubricated flow of the grains due to the intergranular l iquid in the mushy zone. (C) 1999 Acta Metallurgica Inc. Published by Elsev ier Science Ltd. All rights reserved.