Homologous temperature dependence of the yield stress of icosahedral quasicrystals and its implication

Abstract

Icosahedral quasicrystals are commonly plastically deformable at high temperatures, but the temperature ranges of the plastic deformation are largely different among different types of the quasicrystal. However, when we convert the upper yield stress vs. the temperature relations for various icosahedral quasicrystals into the non-dimensional stress normalised by Young's modulus E vs. the non-dimensional temperature normalised by (: the average atomic diameter, k_B : the Boltzmann constant), the date fall around a universal curve. This homologous relation indicates that the deformation mechanism is common to all types of icosahedral quasicrystals. Assuming that the plasticity is carried by dislocation climb process, it is concluded that about a half of the activation enthalpy of the dislocation climb is due to the jog-pair enthalpy and the other half to the enthalpy of vacancy diffusion, both of which are a function of .