Plastic-deformation dependence of the Grueneisen parameter strain derivatives

The strain derivatives of the Grueneisen parameter γ at room temperature are experimentally found to strongly depend on the plastic deformation epsilon sub(p) imposed to the solid. γ is very sensitive to the alterations of the microstructure, which in turn remarkably influences the lattice dynamics of the crystal. To test such a complex interaction, measurements were performed on α-titanium at values of epsilon sub(p) up to 10-1. The obtained exponential relations between the strain derivatives of γ at the origin and the epsilon sub (p) are discussed for the first- and the second-order derivatives, delta γ/delta epsilon0 and delta 2γ/delta epsilon20, respectively. The results allow not only for a deeper knowledge of the γ behaviour, but also for outlining the work-hardening evolution in metallic materials