Formation, solid solution hardening and softening of nanocrystalline solid solutions prepared by mechanical attrition

Abstract

Nanocrystalline Ti 100 − x Cu x ( x = 0–8), Nb 100 − x Cu x ( x = 0–20), Ni 100 − x Cu x ( x = 0–50), Cr 100 − x Cu x ( x = 0–20), Fe 100 − x Cu x ( x = 0–15). Cu 100 − x Ni x ( x = 0–50), Cu 100 − x Fe x ( x = 0–50) and Cu 100 − x Co x ( x = 0–50) solid solutions have been prepared by mechanical attrition of elemental powder mixtures. X-ray diffraction, differential scanning calorimetry, and microhardness measurements are utilized to investigate the structural evolution and the thermal and mechanical properties of the solid solutions. The strength of the nanocrystalline solid solution depends on both solid solution hardening and grain boundary hardening while the latter makes the major contribution to the total strength. The increase or decrease in hardness is dependent on the combined effects of solid solution hardening and either increased or decreased hardness resulting from changes in grain boundary hardening.