Microstructure and Properties of Rapidly Solidified Cu–0.81Cr–0.12Zr Alloy

Abstract

Cu0.81 mass%Cr0.12 mass%Zr alloy was spun into ribbon and then aged at different temperatures for different time. The microstructure, microhardness and electrical conductivity were investigated. It is found that the mother alloy ingot solidified under conventional conditions consists of three phases: Cu matrix, Cr and Cu 5 Zr. Rapid quenching makes Cr and Zr fully dissolve into the copper matrix. As the aging proceeds, Cr and Cu 5 Zr phases precipitate again from the matrix. The ribbon aged at 773 K for 15 min possesses the best property: a microhardness of 212 HV and an electrical conductivity of 78.9% IACS. Compared with the conventional process (homogenization treatment of a bulk alloy ingot followed by aging), the use of rapid quenching doubles the microhardness while only slightly decreasing the electrical conductivity.

Tailoring the composition of the functional Cu–Cr–Zr–La/Ce alloys for electromechanical applications

“…It is worth stating that, upon solidification of the Cu–Cr–Zr system, Cu-rich precipitates are first solidified from the melt. Then, Zr-rich precipitates envelope the Cr-rich precipitates forming a Zr-rich shell around a core of Cr-rich precipitates [1,3,15,17,18,22]. Thence, the presence of Zr prevents the growth of Cr-rich precipitates upon solidification and aging while it has an insignificant effect on the grain size of the matrix structure in the studied conditions.…”

“…The precipitate characteristics, electrical conductivities, and mechanical properties of various functional Cu-Cr-Zr alloy compositions, with and without rare earth element additions, were studied after aging at temperatures ranging from 250 to 600°C for periods ranging from 0 to 24 h [1,2,6,8,9,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. All studies concluded that achieving the best integration of high electrical conductivity, high strength, high hardness, and high wear resistance can be achieved via tailoring the processing parameters and chemical composition.…”

“…Raising the aging temperature shortens the aging time required to attain the peak property. It is reported that the recommended aging time at this range of temperatures is below 2 h, depending on the alloy composition [14][15][16]19,23]. Therefore, aging at 500°C for up to 1.5 h was adopted for this work.…”

“…These alloys are commonly used in the manufacture of electrochemical components, such as motor and high-speed railway contact materials [1,4,6,7]. Several efforts have been made to harmonise the strength and electrical properties of the functional Cu–Cr–Zr alloys through adjustment of the alloy design and processing procedure [1-4,6-27] aiming at extending their industrial applications.…”

“…Second, alloying Cu–Cr–Zr alloys with rare earth elements for purification and enhancing the properties, along with precipitation hardening treatment to produce aged castings without the need for plastic deformation, aims at reducing the processing cost. Thirdly, selecting a relatively high aging temperature (500°C) from the recommended range of 450–500°C for Cu–Cr–Zr alloys, according to the previous works [1,8,9,11,15,21,23], to avoid a long aging time aimed at lowering the processing costs. Raising the aging temperature shortens the aging time required to attain the peak property.…”