Strength and Plasticity of Ultra-Fine Grained Zirconium at Low Temperatures
Plasticity of ultra-fine grained (UFG) zirconium (grain size ~ 0.4 µm), produced by intensive plastic deformation (IPD) - a combination of extrusion, annealing, and drawing, have been studied within the temperature range 300 – 4.2 K in uniaxial compression. It was found that decrease of grain sizes in the result of IPD leads to considerable increase of strength characteristics for the UFG zirconium in comparison with coarse-grained (CG) zirconium (in 6 times at 300 K and 4 times at 77 K); and plasticity of the UFG zirconium keeps rather large (strain > 0.15). Two stages of the strain-hardening and decrease of the activation volume for plastic flow with deformation have been registered. A conclusion was made about the identity of basic deformation mechanisms in the UFG and CG zirconium: simultaneous action and mutual influence of intragrain dislocation gliding and twinning.
Yuri Estrin and Hans Jürgen Maier
E. D. Tabachnikova et al., "Strength and Plasticity of Ultra-Fine Grained Zirconium at Low Temperatures", Materials Science Forum, Vols. 584-586, pp. 452-457, 2008