Grain characteristics, electrical conductivity, and hardness of Zn-doped Cu\u20133Si alloys system

K C Nnakwo,I U Okeke,P A Oghenekowho,E A Maduka,F O Osakwe,B C Ugwuanyi

doi:10.1007/s42452-021-04784-1

Abstract

The grain characteristics, electrical conductivity, hardness, and bulk density of Cu–3Si–(0.1—1 wt%)Zn alloys system fabricated by gravity casting technique were investigated experimentally using optical microscopy (OM), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The study established the optimal alloy composition and the significance of zinc addition on the tested properties using response surface optimal design (RSOD). The cooled alloy samples underwent normalizing heat treatment at 900 °C for 0.5 h. The average grains size and grains distribution were analyzed using the linear intercept method (ImageJ). The microstructure examination revealed a change in grain characteristics (morphology and size) of the parent alloy by addition of 0.1 wt% zinc. The average grains size of the parent alloy decreased from 12 µm to 7.0 µm after 0.1 wt% zinc addition. This change in grain characteristics led to an increase in the hardness of the parent alloy by 42.2%, after adding 0.1 wt% zinc. The electrical conductivity of the parent alloy decreased from 46.3%IACS to 45.3%IACS, while the density was increased by 8.4% after adding 0.1 wt% zinc. The statistical data confirmed the significance of the change in properties. The result of optimization revealed Cu–3Si–0.233Zn as the optimal alloy composition with optimal properties. The Cu–3Si–xZn alloy demonstrated excellent properties suitable for the fabrication of electrical and automobile components.

Highlights

The superconductivity, ductility, and malleability of copper guarantee its choice over other non-ferrous materials for the fabrication of electrical devices and building components
Xiao et al [33] in their study increased the electrical conductivity of the Cu–Ni–Si alloys from 32.7%International Annealed Copper Standard (IACS) to 47%IACS through single addition of zirconium and subsequent thermomechanical treatment
The density of the parent alloy was increased by 8.4% after adding 0.1 wt% zinc (Fig. 3)

Summary

Introduction

The superconductivity, ductility, and malleability of copper guarantee its choice over other non-ferrous materials for the fabrication of electrical devices and building components. Li et al [19] in their study was able to obtain Cu–8.0Ni–1.8Si–(0.6Sn + 0.15 Mg) alloys with maximum electrical conductivity of 26.5%IACS and hardness of 345 HV through work hardening and subsequent aging heat treatment. Xiao et al [33] in their study increased the electrical conductivity of the Cu–Ni–Si alloys from 32.7%IACS to 47%IACS through single addition of zirconium and subsequent thermomechanical treatment. A study carried out by Yi et al [34] established that, with the addition of Ag, work hardening, and subsequent aging heat treatment, Cu–2.0Ni–0.5Si alloy recorded average micro-hardness (203 HV) and electrical conductivity (36.4%IACS). Researchers have explored different mechanisms for the development of high strength, hardness, and superconductive copper-based alloys, but the achievement of combined excellent properties remains difficult. The experimental data were analyzed statistically using RSOD to establish the significance of zinc addition on the measured properties, the optimal alloy composition, and generate model equations for subsequent applications

Experimental procedure

Response surface optimal design

Statistical analysis of the experimental results

Conclusion

Grain size distribuƟon