Structure and mechanical properties of Al-Ca-(Fe, La) eutectic alloys after equal-channel angular pressing

The effect of equal channel angular pressing (ECAP) on the structure and mechanical properties of two eutectic alloys, namely Al-6 % Ca-1 % Fe and Al-5 % Ca-3 % La, was studied. The as-cast alloys were processed by ECAP through 4 passes at 200 degrees C. According to the results obtained, the Al-6 % Ca-1 % Fe alloy is more prone to hardening during ECAP than the Al-5 % Ca-3 % La alloy. As a result of ECAP, the yield strength of the Al-5 % Ca-3 % La and Al-6 % Ca-1 % Fe alloys increased by 1.5 and 2.8 times for, respectively. The relative elongation of the ECAP processed Al-5 % Ca-3 % La and Al-6 % Ca-1 % Fe alloys was 9 and 2 %, respectively. In the ECAP processed Al-6 % Ca-1 % Fe alloy the eutectic structure disappears, and a high dislocation density accumulates; while in the ECAP-processed Al-5 % Ca-3 % La alloy the eutectic structure is retained, and the dislocation density increases slightly. The results obtained confirm that that lanthanum, even in small quantities, being part of complex eutectics, has a decisive influence on the microstructure formation and mechanical properties of Al-Ca alloys.