Mechanical behavior of zirconium and hafnium in tension and compression

Abstract

The mechanical behavior and substructural evolution of highly textured hafnium (Hf) has been examined in tension and compression and compared to the mechanical response of zirconium (Zr). The quasi-static work-hardening rate as a function of strain for both metals exhibits a compression-tension asymmetry. Both Zr and Hf exhibit a downward work-hardening response in tension, while each displays a parabolic and then concave upward work-hardening behavior in compression. Additionally, Hf displays higher flow stresses than Zr both in tension and compression. The stress-strain and strain-hardening curves for Zr and Hf have been characterized in terms of their propensity for deformation twinning and evolution of substructure with strain. Differences in the work-hardening rates and flow stresses as a function of the sense of the applied load and material are discussed in terms of slip-twin interactions during deformation.

Combined size and texture-dependent deformation and strengthening mechanisms in Zr/Nb nano-multilayers

“…External factors such as temperature and strain rate were also found to affect the deformation mechanism in α-Zr. However, hcp metals deformed in a quasi-static mode at ambient temperature, as it is the case in this study, are found to yield mainly by slip and work harden through a combination of slip and twinning [82]. Based on these intrinsic (material dependent) and extrinsic (test dependent) aspects, the major factor to determine the strength of α-Zr in this study is associated with the crystallographic orientation of α-Zr with respect to stresses.…”

“…For L = 27 nm, the basal plane of α-Zr is oriented normal to the loading direction, therefore basal slip is ruled out as a dominant slip system. Zr samples compressed along the c-axis were found to exhibit the highest yield stress and work hardening with respect to other orientations [82]. In view of the limited possibility for a prismatic slip system to be activated due to the unfavourable c-axis orientation with respect to the loading direction, pyramidal slip systems are preferred for L = 27 nm.…”

A novel use of PDV for an integrated small scale test platform

“…The average grain size was 35 µm and the heat-treated plate had a strong 0001 basal texture, similar to that in [6]. Spherically-nosed, bullet shaped specimens of approximately 7.4 mm in diameter and 7.9 mm in length were machined from this plate.…”

Acoustic emission in hafnium under tensile deformation

“…Nowadays, hafnium is widely used in control rods for nuclear reactors, in neutron-absorbing containers, in developing special alloys [1-3]. Its successful use and extension of the range of its applications call for further investigation of the influence of structural factors on the physical-mechanical properties of the material.Numerous research efforts undertaken recently [4][5][6][7] have been focused on a study of the mechanisms of plastic deformation in hafnium depending on the structural state and test conditions. The investigations of plastic deformation and fracture processes in metals and the inspection of the material structural state involve an extensive use of the acoustic emission (AE) method [8][9][10][11].…”

“…Numerous research efforts undertaken recently [4][5][6][7] have been focused on a study of the mechanisms of plastic deformation in hafnium depending on the structural state and test conditions. The investigations of plastic deformation and fracture processes in metals and the inspection of the material structural state involve an extensive use of the acoustic emission (AE) method [8][9][10][11].…”