Enhancement of strength and stability of nanostructured Ni by small amounts of solutes

Polycrystalline Ni with a purity of 99.7% (with 0.14% Ti) has been deformed by high-pressure torsion at room temperature to εvM = 100. The presence of solute atoms markedly raises both the strength and the thermal stability, showing a flow stress of about 1700 MPa and a recrystallization temperature of about 500 °C. The effect of the solute on dislocation storage during deformation and on the mobility of dislocations and boundaries during annealing are discussed. The strengthening mechanisms and their superposition are also analyzed.