Dynamic yielding of single crystal Ta at strain rates of ∼5 × 105/s

Abstract

A magnetic loading technique was used to produce planar ramp loading of [100] and [110] orientations of single crystal tantalum to peak stresses of either ∼18 or ∼86 GPa for applied plastic strain rates of about 2 × 106/s. It was found that the dynamic elastic limit varied only slightly for factor-of-2 changes in the resulting elastic strain rates near 5 × 105/s. For wave propagation in the [100] direction, the dynamic elastic limit varied from 4.18–3.92 GPa for corresponding sample thicknesses of 0.625–1.030 mm and exhibited a slight rate dependence for the strain rate region studied. For [110] compression, the elastic limit was essentially independent of propagation distance, but exhibited a significant sample-to-sample variation; the elastic limit for this orientation varied from 2.49–3.18 GPa over sample thicknesses of 0.702–1.023 mm, with an average and standard deviation for the data of 2.93 ± 0.27 GPa. There was no apparent rate dependence in this case for the strain rates examined.