Structural evolution and hardness of molybdenum deformed by high pressure torsion at 573 K

Abstract The structural evolution of initial single-crystal {110} Мо during high pressure torsion at 573 К has been investigated by scanning and transmission electron microscopy. Two stages of the structure formation have been found. At the first stage, the single-crystal transforms into the polycrystal with a {110} weak texture. At the second stage (е ≥ 4), the average grain size is constant (about 0.5 μm) due to dynamic recrystallization. An increase in the gradient of an internal grain orientation (grain orientation spread) after the maximally-achieved true strain (е = 7.1) indicates the high defectiveness of the dynamically-recrystallized structure and, as a result, a rise in the hardness of Mo.