Structure and Properties of Al–0.6wt.%Zr Wire Alloy Manufactured by Direct Drawing of Electromagnetically Cast Wire Rod

Nikolay Belov,Maxim Murashkin,Victor Timofeev,Torgom Akopyan,Natalia Korotkova

doi:10.3390/met10060769

Abstract

The method of electromagnetic casting (EMC) was used to produce the long-length rod billet (with a diameter 12 mm) of aluminum alloy containing 0.6 wt.% Zr, 0.4%Fe, and 0.4%Si. The combination of high cooling rate (≈104 K/s) during alloy solidification and high temperature before casting (≈830 °C) caused zirconium to dissolve almost completely in the aluminum solid solution (Al). Additions of iron and silicon were completed in the uniformly distributed eutectic Al8Fe2Si phase particles with an average size of less than 1 µm. Such fine microstructure of the experimental alloy in as-cast state provides excellent deformability during wire production using direct cold drawing of EMC rod (94% reduction). TEM study of structure evolution in the as-drawn 3 mm wire revealed the onset of Al3Zr (L12) nanoparticle formation at 300 °C and almost-complete decomposition of (Al) at 400 °C. The distribution of Zr-containing nanoparticles is quite homogeneous, with their average size not exceeding 10 nm. Experimental wire alloy had the ultimate tensile strength (UTS) and electrical conductivity (EC) (234 MPa and 55.6 IACS, respectively) meeting the AT2 type specification. At the same time, the maximum heating temperature was much higher (400 versus 230 °C) and meets the AT4 type specification.

Highlights

Aluminum alloys containing the addition of zirconium (0.2–0.4 wt.%) are widely used for manufacturing of heat resistant wires
Zirconium should be fully dissolved in the aluminum solid solution (hereinafter (Al)) during solidification
The experimental aluminum alloy, containing 0.6%Zr, 0.4%Fe and 0.4%Si, was manufactured by the method of electromagnetic casting (EMC) in the form of long-length manufactured by the method of electromagnetic casting (EMC) in the form of long-length rod 12 rod 12 mm in diameter

Summary

Introduction

Aluminum alloys containing the addition of zirconium (0.2–0.4 wt.%) are widely used for manufacturing of heat resistant wires. Such alloys possess the improved combination of electrical conductivity, mechanical properties, and, thermal stability [1,2,3]. Society for Testing and Materials (ASTM) specification (AT1-AT4 types) for the heat resistance [1], the microstructure should have a sufficient amount of Zr-containing precipitates Al3 Zr having L12 crystal lattice) [6] These precipitates should have a size within 10 nm and uniform distribution. To obtain such nanoparticles, zirconium should be fully dissolved in the aluminum solid solution (hereinafter (Al)) during solidification. The microstructure of Al–Zr wire alloy depends considerably on the processing root, melting and casting temperatures and parameters of annealing [6,12,13]

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