A deformation mechanism map for IN738LC superalloy

Deformation maps are a useful means of presenting data which span a wide variety of experimental conditions. Newly obtained data are presented in this form for the isothermal creep properties of the directionally solidified IN738LC alloy, which is often employed in gas turbine high pressure blading. The data indicate a high-stress plasticity regime controlled by dislocation glide, a power-law creep field, and a strong indication of a vacancy-diffusion creep field at low stresses. The curvature of the temperature contours at high stress may be due to a low- temperature dislocation-core diffusion-controlled power-law creep field, or to power-law breakdown, or to both. (O.C.)