The mechanical property and electrical conductivity evolution of Al-Fe alloy between room temperature and elevated temperature ECAP

Ultra-fine grained Al-Fe alloy rods were manufactured by Equal-channel Angular Pressing (ECAP) at the two temperatures (room temperature (RT) and elevated temperature (ET)). Microstructure, mechanical properties, and electrical conductivity exhibited an abnormal evolution between RT-ECAP and ET-ECAP. A strong dissolution of micron Al3Fe and Al6Fe precipitations has been demonstrated in this immiscible Al-Fe alloy systems at such a few strains during the ET-ECAP. The Fe solid atoms dissolved back into the matrix, induced high-density dislocation and accelerated the grains refinement. It contributed to the finer grains, higher strength as well as dramatic decreased electrical conductivity in ET-ECAP. Meanwhile, the agglomeration and growth of nanoparticles decreased its dispersity in matrix distribution in RT-ECAP, leading to strength in RT-ECAP shown a stable or even decrease tendency, while strength constantly grew in ET-ECAP. Based on the feature of dissolution and precipitation, a high strength combined with a considerable electrical conductivity of this investigated Al-Fe alloy has been simultaneously achieved by the modified ECAP routes using 4 ECAP passes at room temperature and then another 4 passes at elevated temperature. The yield stress (-178.0 MPa) and electrical conductivity (-61.55%) are superior to the convention ECAP routes of 8 RT-ECAP passes and 8 ET-ECAP passes.

Automated summary

The study revealed that in high temperature ECAP process, micron Al3Fe and Al6Fe precipitates dissolved, leading to the dissolution of Fe solid atoms and accelerated grain refinement, enhancing the alloy's strength but decreasing its electrical conductivity. In room temperature ECAP process, agglomeration and growth of nanoparticles decreased dispersity, resulting in a stable or decreasing trend in strength.