Role of lattice strain on thermal stability of a nanocrystalline FeMo alloy

The thermal stability of a nanocrystalline Fe–1.5 wt.% Mo powder milled with nano-SiO2 was investigated in situ by synchrotron radiation X-ray diffraction. Crystallite size is stabilized by the grain-boundary strain, therefore grain growth starts only after a certain amount of this strain has been released. The phenomenon was rationalized by a micromechanics approach, which considers the equilibrium between forces acting on the grain boundary surface.