Microstructural evolution and superior properties of conductive Al–Fe alloy processed by ECAP

Abstract

The new conductive Al–Fe alloy (AA8176) is used in power transmission due to its high electrical conductivity. As a non-agе-hardenable alloy, Al–Fe alloy is not a subject for the strength improvement. So, Equal-channel Angular Pressing (ECAP) is introduced to try to develop the advanced Al–Fe alloy with improved mechanical performance and good electrical conductivity. After different number of passes at room temperature, its electrical conductivity is maintained at quite high value (>60% IACS), close to that of pure aluminum, and its change during ECAP processing is insignificant. At the same time, the yield strength increases sharply from 46 MPa to a nearly 200 MPa after 8 passes. Elongation to failure also increases to 11% with increasing the number of passes. Superior combination of strength and electrical conductivity was demonstrated in alloys subjected to ECAP. Also, the study of microstructural evolution with a close attention to the evaluation of grain size, misorientation angle, size and distribution of Al–Fe intermetallic particles was performed. ECAP shows different advantages and potential in Al–Fe alloy performance improvement by achieving the ultra-fined grains and high-density dislocations through the imposed strain, instead of the formation of abundant precipitates in alloys through traditional heat treatment.