Bioinert Zr-1Nb alloy, which is a prospective material for the fabrication of implants for different applications, is studied. Annealed billets of the alloys are subjected to severe plastic deformation including multi-cycle abc-pressing and multipass rolling in grooved rolls. The abc-pressing stage involves three cycles of pressing within the temperature range 500 – 400°C with one pressing in each cycle at a given temperature. In the second stage, the billets are deformed through rolling in grooved rolls at room temperature. Rolling in grooved rolls provided the formation of a homogeneous structure throughout the bulk billet volume and additional grain refinement. After annealing the alloy had a fine-grained structure consisting of 2.8 μm sized equiaxial α-Zr matrix grains and 0.4 μm sized β-Nb particles distributed on the boundaries and interiors of α-Zr matrix grains. As a result of severe plastic deformation, a binary ultrafine-grained alloy with 0.2 μm size of structural elements was obtained. Transmission electron microscopy shows that the microstructure of the alloy consists of α-Zr grains, while β-Nb phase grains are not identified structurally or via X-ray diffraction. Only the diffraction identification analysis reveals the presence of β-Nb in the alloy. Ultrafine-grained structure enhances the mechanical properties of the alloys: yield stress 450 MPa, ultimate tensile strength 780 MPa, and microhardness 2800 MPa are obtained while keeping a low value of Young's modulus (51 MPa) comparable to the Young’s modulus of bone tissue.
ASJC Scopus subject areas
- Materials Science(all)