Peculiarities in plastic deformation of polycrystalline yttrium

The mechanical properties and plastic deformation characteristics of the polycrystalline yttrium have been studied during stretching in the region of 77-673 K, at the deformation rate amounting to 10-3-10-5 s-1. Anomalous behaviour of the ultimate strength and yield during testing within the 300-500 K range has been pointed out. This is related to the yttrium deformation ageing process that has been proved by experiment. It is assumed that the plastic flow is related to the cross slip or to the overcomimng of the foreign atoms dislocation when deformation ageing is not spotted