Research of mechanical and electrical properties of Cu–Sc and Cu–Zr alloys

Abstract

The research paper presents the impact of the scandium additive and various conditions of the heat treatment on copper mechanical, electrical and heat resistance properties. The performed research works included manufacturing of CuSc0.15 and CuSc0.3 alloys through metallurgical synthesis with the use of induction furnace and following crystallization in graphite crucibles at ambient temperature. Additionally, a CuZr0.15 alloy was produced as a reference material for previously synthesized Cu-Sc alloys. During research, the selection of heat treatment for the produced materials was conducted in order to obtain the highest mechanical-electrical properties ratio. Materials obtained in such a way were next subjected to thermal resistance tests. Parameters of thermal resistance test included temperatures from the range of 200-700 °C and 1 h of annealing time. The research has shown that CuSc0.15 and CuSc0.3 alloys have higher heat resistance after their precipitation hardening compared to the Cu-Zr alloy. The paper also presents microstructural research of the produced materials, which showed that alloying elements precipitates are mainly localized at the grain boundaries of the material structure.

Copper-Based Alloys with Optimized Hardness and High Conductivity: Research on Precipitation Hardening of Low-Alloyed Binary CuSc Alloys

“…All experimental data on the hardness and electrical conductivity of specimens, without cold working performed prior to aging, were consistent and correlated with the published results of Franczak et al [33]. Furthermore, the investigated visual precipitates appeared in lamellar structures, corresponding to the published investigation of strengthening effects [35] and their expected structure [2].…”

“…Hao et al demonstrated the precipitation mechanisms, formation, and growth of Cu 4 Sc phases from the supersaturated solid solution, with detailed TEM investigations [35]. Focusing on moderate degrees of cold deformation before the aging process, the conducted research closed the gap between specimens aged directly after solution annealing and quenching, by Franczac et al [33], and specimens with enhanced degrees of deformation prior to the aging process, by Hao et al [35]. Referring to Hao et al, XRD measurements were conducted to verify the same crystallographic structure of the precipitates.…”

“…The Cu-Sc phase diagram shows three intermetallic compounds, including Cu 4 Sc (15 wt.% Sc), Cu 2 Sc (26 wt.% Sc), and CuSc (42 wt.% Sc) [26]. A quenched solution of scandium in copper can be used in aging treatments, in order to increase hardness and electrical conductivity [31][32][33][34]. Hao et al describe the precipitating process of copper containing 0.4 wt.% scandium after 90% cold deformation (at room temperature) and cryogenic rolling before an ensuing aging process [35]: Starting in supersaturated solid solution, regularly distributed scandium-enriched atomic clusters develop in the first step.…”

“…Whereas Franczak et al analyze as-cast structures of CuSc0.15 and CuSc0.3 and the behavior of precipitation without prior cold deformation [33], in direct comparison to the already named benchmark alloy CuZr0.15, Hao et al focus on the behavior of strongly cold-worked specimens of CuSc0.4 [35], which provides a gap for moderate degrees of cold deformation to be further investigated.…”

DSC Analysis of the Effect of Cold Deformation on the Precipitation Kinetics of a Binary Cu-SC Alloy

“…Recently published studies by Franczak et al [8] and Dölling et al [9] show that a combination of copper and scandium elements has potential in terms of electrical conductivity and mechanical strength in addition to having advantages in terms of recrystallization behavior and grain refinement [9][10][11]. In particular, cold working prior to precipitation hardening increases the density of dislocations and strain-induced defects in the material, creating more nucleation sites for the precipitation of the fine precipitates.…”