International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

ECAP was carried out with a gradual decrease in temperature and an increase in the number of passes on two medical magnesium alloys: WE43 (Mg-3.56%Y-2.20%Nd-0.47%Zr) and ZX10 (Mg-1.0%Zn-0.3%Ca). It was shown that ECAP leads to a significant refinement of the alloys structure. For ZX10 alloy, the average grain size after ECAP decreased from ~ 105 μm in the initial state to 8 ± 0.18 μm in the longitudinal section and to 4 ± 0.19 μm in the transverse one. For the WE43 alloy, the average grain size was changed from 70 μm to 0.69 ± 0.13 μm and the precipitation of particles of the Mg41Nd5 phase with an average size of 0.45 ± 0.18 μm was also discovered. At the same time, the grain refinement led to an increase in the strength characteristics of the both alloys (including fatigue strength), and increased prismatic slip activity (along with the formation of an inclined basal texture in ZX10 alloy) led to an increase in their ductility. The alloy structure formed during the ECAP process does not lead to a decreasing in resistance to chemical corrosion.

In the present work, the magnesium alloy WE43 (Mg-Y-Nd-Zr) after high pressure torsion (HPT) was investigated. HPT was conducted at room temperature, 200 °C or 300 °C. As a result of HPT processing, a large number of twins with the twin size of 0.4 − 8.1 µm were formed. Furthermore, the HPT process led to the formation of a very fine grain structure with the average grain size of 30 – 100 nm. The deformation by HPT caused the formation of a displaced basal texture, which sharpens with an increase in the deformation temperature. The refinement of the microstructure brought about an improvement of the microhardness of the alloy over the as-received condition. The microhardness after HPT at the room temperature increased up to 1189 ± 33MPa compared with 774 ± 50 MPa in the initial state. A subsequent aging after HPT led to an additional strengthening to a level of 1411 ± 40 MPa. It was noted that thermal stability of strengthening caused by HPT did not depend on the deformation temperature and sustained up to 250 °C.