Microstructure and mechanical properties of novel Al-Y-Sc alloys with high thermal stability and electrical conductivity

The microstructure and mechanical properties of novel Al-Y-Sc alloys with high thermal stability and electrical conductivity were investigated. Eutectic Al3Y-phase particles of size 100-200 nm were detected in the as-cast microstructure of the alloys. Al3Y-phase particles provided a higher hardness to as cast alloys than homogenized alloys in the temperature range of 370-440 degrees C. L1(2) precipitates of the Al-3(ScxYy) phase were nucleated homogenously within the aluminium matrix and heterogeneously on the dislocations during annealing at 400 degrees C. The average size of the L1(2) precipitates was 11 +/- 2 nm after annealing for 1 h, and 25-30 nm after annealing for 5 h, which led to a decrease in the hardness of the Al-0.2Y-0.2Sc alloy to 15 HV. The recrystallization temperature exceeded 350 degrees C and 450 degrees C for the Al-0.2Y-0.05Sc and Al-0.2Y-0.2Sc alloys, respectively. The investigated alloys demonstrated good thermal stability of the hardness and tensile properties after annealing the rolled alloys at 200 and 300 degrees C, due to fixing of the dislocations and grain boundaries by L1(2) precipitates and eutectic Al3Y-phase particles. The good combination of strength, plasticity, and electrical conductivity of the investigated Al-0.2Y-0.2Sc alloys make it a promising candidate for electrical conductors. The alloys exhibited a yield stress of 177-183 MPa, ultimate tensile stress of 199-202 MPa, elongation of 15.2-15.8%, and electrical conductivity of 60.8%-61.5% IACS. (C) 2019 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.