Fiber phase in Cu-Fe-Cr in situ composites

Cu-16Fe-2Cr (mass fraction, %) in situ metal matrix composites were manufactured by inductive melting, casting, forging and cold drawing. The final wire (eta = ln(A(0)/A)= 5.42, .A(0) and A are original and final cross sectional areas, respectively) has a strength of 980 MPa. The fibers in Cu matrix were extracted by use of a selective etching technique, where the Cu matrix dissolved by nitric acid, and then the morphology of the fibers were observed. using SEM and TEM. At lower drawing strains, some of Fe-Cr fibers have the same bcc single-crystal structure as that of dendrites in the as-cast state. The EDP indicates that the fibers have a (110) texture. At higher drawing strains, a single fiber is divided into parallel subunits with about 100 nm width. These subunits are separated by distinct grain boundaries. Relative angle differences across the grain boundaries are from 11degrees to 82degrees. The strength of in situ composites is also discussed in terms of a Hall-Petch effect.