TEM observation of DO3 structure in Fe3Al alloy with Mn addition

The structures of DO3 Fe-28Al-1.5Mn alloy, including ordering degree, super dislocation, APD and APB, were investigated by TEM. The results showed that addition of manganese into DO3 Fe3Al could not change the ordered type of the alloy, but could reduce APD size and then reduce ordering degree of the alloy. The fourfold superdislocations were retarded in DO3 Fe3Al alloy aft er Mn addition. Undeformed alloy with Mn has mainly twofold superdislocatio ns. As deformation increases, the twofold superdislocations slip and decomp ose into unit dislocations, and unit dislocations slip and slip cross, read ing to better ductility. The deformation mechanism of DO3 Fe-28Al-1.58Mn al loy was controlled at first by twofold superdislocation and at last by unit superdislocation. (C) 1999 Kluwer Academic Publishers.