In order to develop alloys with high temperature capabilities, it is very important to develop computer programs for designing alloys so as to avoid inefficient try-and-error-type experiments. Our research group thus firstly developed an alloy design program (ADP) for the prediction of some mechanical properties in Ni-base superalloys. ADP is based on regression analysis of experimental data accumulated, and by inputting composition of alloys designed, you can obtain such information as g / g' equilibrium composition, solvus / solidus temperatures, creep rupture life at 1040oC at 137 MPa, corrosion resistance etc. A more fundamental approach, we have been applying the cluster variation method (CVM) to Ni-base superalloys and precious metal group PGM- based refractory superalloys. This method employs Lennard-Jones pair potentials, and allows the equilibrium phase chemistries, volume fractions and lattice parameters to be estimated as a function of alloy composition, temperature and pressure.
It is also important to understand the temporal and spatial evolution of the atomic arrangement in materials. A Monte Calro simulation (MCS) has been employed to obtain such information in Ni-base superalloys.
Currently, we have started to conduct molecular dinamics (MD) to predict the movement of individual atoms in Ni-base alloys.
These numerical methods will be combined to bring useful information in designing new materials.
(H. Murakami)