J. Mater. Sci. Technol. ›› 2020, Vol. 36: 1-6.DOI: 10.1016/j.jmst.2019.08.006

• Research Article •     Next Articles

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

A.V. Pozdniakov, R.Yu. Barkov*()   

  1. NUST “MISiS”, Leninskiy ave. 4, 119049, Moscow, Russia
  • Received:2019-02-11 Revised:2019-05-10 Accepted:2019-06-03 Published:2020-01-01 Online:2020-02-11
  • Contact: Barkov R.Yu.

Abstract:

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 °C. L12 precipitates of the Al3(ScxYy) phase were nucleated homogenously within the aluminium matrix and heterogeneously on the dislocations during annealing at 400 °C. The average size of the L12 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 °C and 450 °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 °C, due to fixing of the dislocations and grain boundaries by L12 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.

Key words: Aluminium alloys, Scandium, Yttrium, Recrystallization, Mechanical properties, Electrical conductivity