Microstructures and Mechanical Properties of Highly Electrically Conductive Cu–0.5, Cu–1 and Cu–2 at%Zr Alloy Wires

Abstract

Hypoeutectic CuZr binary alloys have originally been studied in order to develop wires with both high strengths and high electrical conductivities. This study aimed to improve the electrical conductivities of Cu0.5, Cu1 and Cu2 at% Zr alloys, which have Zr contents lower than those of high-strength Cu3, Cu4 and Cu5 at% Zr alloys. Cast rod samples, whose lengths and diameters were 180 and 12 mm, respectively, were prepared by copper-mold casting and wire-drawn to diameters in the range of 10.031 mm (drawing ratio, © = 4.811.1). The microstructures and mechanical properties of the obtained wires were investigated and compared to those of Cu3, Cu4 and Cu5 at%Zr alloy wires that had been investigated in a previous study.The eutectic phases found in the cast rods consisted of ¡-Cu primary phases and phases of the intermetallic compound Cu 5 Zr. The eutectic phases became isolated, like small islands, in the matrices, and their volume fractions decreased with a decrease in the Zr content. The orientations of the ¡-Cu and Cu 5 Zr phases around the boundaries of these eutectic phases were similar. After the wiredrawing process, the intermetallic compound in the eutectic phases transformed into Cu 9 Zr 2 in the case of the Cu0.5 at%Zr alloy and into Cu 8 Zr 3 in the case of the Cu1 at%Zr alloy. The electrical conductivity (EC) and ultimate tensile strength (UTS) values of the alloys depended on the volume fractions of their eutectic phases. However, the changes in these properties with the change in the drawing ratio were smaller than those in the case of the high-strength Cu3, Cu4 and Cu5 at%Zr alloy wires. The EC and UTS values of the Cu0.5, Cu1 and Cu2 at%Zr alloy wires drawn at values of © greater than 8.0 were 6183% IACS (International Annealed Copper Standard) and 6901010 MPa, respectively. When combined together, wires of the resulting hypoeutectic CuZr binary alloy exhibited EC and UTS values of 1683% IACS and 6902234 MPa, respectively. These results showed that instead of there being a tradeoff between these properties, the values of both these properties increased at the same time.

Characteristics of Hypoeutectic Cu–Zr Alloy Rods Manufactured by Vertically Upwards Continuous Casting

“…The similarity of the channelling patterns of these Kikuchi lines means that the material had the same orientation at points X, Y, and Z. The same microstructure was obtained for the Cu-0.5Zr, Cu-1Zr, and Cu-2Zr alloy rods produced by CMC 20) . Figure 13 shows a high-magnication bright-eld (BF) TEM image of the eutectic phase shown in Fig.…”

“…Therefore, the authors of this study investigated hypoeutectic Cu-xZr (x = 0.5-5 at%) alloys produced by copper mold casting (CMC) and reported the following characteristics: (i) the ne dendritic microstructure of the as produced Cu-xZr alloys; (ii) the change in Cu-xZr alloy microstructure after heavy wire-drawing to form a lamellar structure of nanometer-scale layers of copper and a Cu/Cu-Zr intermetallic eutectic phase; inducible to the increase in the wire strength with maintaining its electrical conductivity; and (iii) the ne balance between strength and electrical conductivity exhibited by the drawn wires [17][18][19][20] . As a result, the ultimate tensile strength and the electrical conductivity of these CuxZr alloy wires reached the value range from a strength of 600 MPa corresponds to a conductivity of 90% IACS to a strength of 2234 MPa corresponds to 16% IACS, which sufciently overcome the above-mentioned trade-off.…”

Microstructures and Mechanical and Electrical Properties of Hypoeutectic Cu-1, C-3 and Cu-5 at%Zr Alloy Wires Preprocessed by Spark Plasma Sintering

“…This suggests that the Cu 5 Zr and Cu phases had different orientations, and there was incoherence between them. This result is in contrast to the coherence between the eutectic (Cu + Cu 5 Zr) and Cu phases in the cast Cu-0.5, Cu-1 and Cu-2 at%Zr alloys previously reported by Muramatsu et al 17) In addition, the microstructures of the SPS Cu-1, Cu-3 and Cu5 at%Zr alloy specimens, shown in Fig. 3, are more homogeneous than those of the cast Cu-0.55 at%Zr alloy rods 13,16,17) and exhibited a finer dual-phased structure.…”

Microstructures and properties of rapidly solidified Cu90Zr10-x Al x alloys

“…The rapid solidification is considered to be a freezing mechanism formed by high solubility of Zr elements in Cu-liquid before injecting into the copper mold. On the other hand, in the Cu 90 Zr 10-x Al x (x=1-9; at.%) alloys, the α-Cu phase (lattice parameters a=b=c=0.3615 nm) and the intermetallic compound Cu 5 Zr (a=b=c=0.6870 nm) have a similar orientation in the eutectic phase [11] . Thus, for the alloy containing 9at.% Zr, a small portion of Zr atoms disperse in the Cu matrix, while others may replace the Cu atoms at a substitutional or interstitial site in the α-Cu phase, resulting in the dispersive fibrous Cu 5 Zr phase.…”

“…Moreover, the similar finestructure composite with micron-sized grains in Cu-based alloys has also been proven beneficial for higher strength. For the Cu-Zr alloys, a fibrous mixed structure of α-Cu and Cu 9 Zr 2 phases has been confirmed to contribute to high fracture strength [11,12] . Abstract: Cu 90 Zr 10-x Al x (x=1, 3, 5, 7, 9; at.%) alloy rods were synthesized based on rapid solidification method.…”