An investigation of the mechanism of thermally activated deformation in certain Ni-Al-Ta and Ni-Al-Hf superalloys

Stress relaxation and strain-rate cycling tests are conducted between room temperature and 8000C to ascertain the deformation mechanisms in terms of 'athermal' and thermally activated processes. Stress relaxation is analysed by using a computer program and incremental unloading technique. From the strain-rate cycling tests the strain-rate sensitivity and activation volumes are calculated. The predictions of the activation analysis are compared with the dislocations observed by transmission electron microscopy. (author)