Effect of different heat treatment on thermal and electrical conductivity, and microhardness of Erbium-reinforced in-situ processed (ZrB2/Al2O3) 7085 AA nanocomposites for high temperature applications

Abstract

High structurally stable 7085 aluminium alloy (7085 AA) is increasingly gaining more attention in industries such as automotive, electrical and high-temperature applications due to its demand for prolonged usage. The performance potential of conventional 7085 AA properties can be enhanced by reinforcing it with appropriate ceramic nanoparticles (AZ), namely, Aluminium oxide (Al2O3), Zirconium diboride (ZrB2), and rare earth metals, i.e. Erbium (Er), which makes it to be utilized for high-temperature industrial applications. Thus, the primary objective of the present study is to develop 7085 AA/AZ-Er composites having enhanced thermal, electrical and mechanical properties. The composites was synthesized through an In-situ process, followed by homogenization, solution treatment and artificial ageing (T6 and T74 heat treatment). The results obtained through T6 and T74 heat treatment were compared. The concentration of AZ was maintained at 1.0 wt.%, whereas Er was varied by 0.1. 0.3 and 0.5 wt.% in the 7085 AA/AZ composites. The superior properties of 7085 AA/AZ- Er composites achieved in this study are as follows: Thermal conductivity- 153.5 ± 0.7 W/m·K, Electrical conductivity- 21.99 ± 0.08 MS/m, and Hardness- 217.12 ± 3.2 Hv. The hardness and thermal conductivity of T6 heat-treated Er-based composites are found to be superior, while T74 heat-treated composites exhibited significant improvements in electrical conductivity. It is concluded that the appropriate addition of Er concentration plays a vital role in enhancing mechanical, electrical and thermal properties irrespective of the heat treatment process.