The investigation of the slippage effect, transformation of the structure and properties of the Zr–1%Nb alloy during high-pressure torsion deformation

High-pressure torsion deformation (HPT) is an effective method for transforming the structure of metallic materials, forming a nanostructural state in them, and significantly improving their strength. However, deformation achieved during HPT can be much less than expected due to the slippage. The study of the slippage effect during HPT of various materials is a topical issue. Previously, the authors proposed a simple and illustrative method for assessing slippage and the actual degree of torsion deformation achieved during HPT. Zr–1%Nb alloys, on which many studies of the HPT effect previously have been carried out, are good material for studying the slippage effect during HPT. Therefore, it is possible to compare obtained data with the results of other authors. The paper investigates the HPT impact on the structure and properties of the Zr–1%Nb alloy and demonstrates the slippage effect. The initial disk, prepared for HPT, was cut into two half-disks that were jointly placed on the strikers and exposed to joint HPT for n=¼ revolutions of anvils. The authors evaluated the slippage effect from the view of halves. The study showed that even at the initial HPT stages at n=¼ revolutions, there is a significant slippage of strikers and a sample, and the torsion deformation does not accumulate as expected. The authors analyzed the influence of various HPT modes on the microhardness, structure, and phase composition of the Zr–1%Nb alloy. The study shows that, despite the slippage effect, the Zr–1%Nb alloy is strongly hardened during HPT for one revolution (n=1) and HPT with n=10; the microhardness and tensile strength increase significantly, and up to 90 % of high-pressure ω-phases is formed in the sample. The authors conclude that during HPT, the deformation is implemented not by simple torsion but by the more complex modes.