The effect of particle size upon the annealing behaviour of plastically deformed two-phase crystals

Two-phase crystals of copper containing dispersed SiO₂ particles and of aluminium containing plates of CuAl₂ (-phase) have been prepared and plastically deformed at room temperature. The changes in dislocation distribution upon isothermal annealing have been followed by electron microscopy.It is shown that misoriented subgrains associated with the dispersed phase form on annealing only if the dislocation interactions during prior straining lead to the development of local lattice curvature in the matrix at these regions. When the dispersed particle size is small (i.e. < 3000 å in diameter) no such recrystallisation embryos are observed, and a microstructure which should provide optimum resistance to recrystallisation is suggested.