CRYSTALLOGRAPHIC ORIENTATION RELATIONSHIPS FOR AL-FE AND AL-FE-SI PRECIPITATES IN ALUMINUM

A number of intermetallic phases have been found in pure aluminum, e. g. theta -Al//1//3Fe//4, Al//6Fe, b. c. c. alpha -AlFeSi, Al//mFe, q//1-AlFeSi and q//2-AlFeSi. Crystallographic orientation relationships between theta -Al//1//3Fe//4 and Al; b. c. c. alpha -AlFeSi and Al; q//1-AlFeSi and b. c. c. alpha -AlFeSi; q//1-AlFeSi and Al and q//2-AlFeSi and b. c. c. alpha -AlFe Si were determined by electron diffraction. The orientation relationships are discussed in terms of lattice matching. The number of variants for each relationship was determined from group theory. The orientation relationships between theta -Al//1//3Fe//4 and Al are explained by the close matching of metal atoms on the interfacial surface between the two phases.