한국주조공학회

The effect of thermal cycling and isothermal exposure on the high temperature microstructural stability of unidirectionally solidified Al-CuAl_2 eutectic composite has been studied. A coarsening procedures of lamellar eutectic structures were initiated at growth fault region because of diffusion through low angle boundary at this region. It was considered that thermally induced residual stresses produced by thermal cycling were high enough to increase the dislocation density in Al- rich matrix phase. However, it was also considered that dislocations generated by these high thermal stresses were annihilated at high temperature by stress relaxation. Consequently, the thermal cycling up to 1440 cycles between 20 and 520℃ did not affect the microstructural stability.