Comparison of GRCop-84 to Other Cu Alloys with High Thermal Conductivities

Abstract

The mechanical properties of six highly conductive copper alloys, GRCop-84, AMZIRC, GlidCop Al-15, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z were compared. Tests were done on as-received hard drawn material, and after a heat treatment designed to simulate a brazing operation at 935 °C. In the as-received condition AMZIRC, GlidCop Al-15, Cu1Cr-0.1Zr and Cu-0.9Cr had excellent strengths at temperatures below 500 °C. However, the brazing heat treatment substantially decreased the mechanical properties of AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z. The properties of GlidCop Al-15 and GRCop-84 were not significantly affected by the heat treatment. Thus there appear to be advantages to GRCop-84 over AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z if use or processing temperatures greater than 500 °C are expected. Ductility was lowest in GlidCop Al-15 and Cu-0.9Cr; reduction in area was particularly low in GlidCop Al-15 above 500 °C, and as-received Cu-0.9Cr was brittle between 500 and 650 °C. Tensile creep tests were done at 500 and 650 °C; the creep properties of GRCop-84 were superior to those of brazed AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z. In the brazed condition, GRCop-84 was superior to the other alloys due to its greater strength and creep resistance (compared to AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z) and ductility (compared to GlidCop Al-15).Keywords GRCop-84, AMZIRC, GlidCop Al-15, Cu-Cr-Zr, Cu-Cr, NARloy-Z, Copper, compression, tension, creep, mechanical properties IntroductionGRCop-84 (Cu-8 at%Cr-4 at% Nb) is a newly-developed copper alloy with an attractive balance of high temperature strength, creep resistance, low cycle fatigue life, and thermal conductivity. Our goal is to compare GRCop-84 to similar commercial copper alloys in a consistent manner. Data on alloys such as NARloy-Z, AMZIRC, GlidCop Al-15 low oxygen grade, Cu-0.9Cr, and Cu-1Cr-0.1Zr can be found in the literature. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] However, the test conditions are rarely matching for "apples-to-apples" comparisons. Most literature also deals only with as-received material. The alloys being considered in this work are used in high temperature applications where high thermal conductivity, high strength, and resistance to creep and low cycle fatigue are required. Such applications include high performance metal gaskets, rocket engine combustion chambers, nozzle liners, and various Reusable Launch Vehicle (RLV) technologies. [1] In regeneratively cooled combustion chamber applications, such as nozzle liners, these alloys are subjected to the combustion gas temperatures on the hot side and are cooled by cryogenic hydrogen flow on the back side. The tensile, creep, low cycle fatigue, and compressive strength of GRCop-84 will be compared to those of the existing commercially available alloys shown in Table 1. To compare the properties these alloys would actually have during use, they were tested in the as-received condition and after a heat treatment designed to simulate a typical high temperature brazing...

A statistical study of the effects of processing upon the creep properties of GRCop-84

“…The magnitude of these processing effects was generally small relative to the variations that have been seen in other high strength, high conductivity Cu-based alloys tested before and after receiving various heat treatments [25]. The work by deGroh et al [25], which closely mirrors this study, examined both precipitation strengthened alloys (Cu-0.9 Cr, Cu-0.15 Zr, Cu-1 Cr-0.1 Zr) and oxide dispersion strengthened alloys (GlidCop AL-15).…”

“…The work by deGroh et al [25], which closely mirrors this study, examined both precipitation strengthened alloys (Cu-0.9 Cr, Cu-0.15 Zr, Cu-1 Cr-0.1 Zr) and oxide dispersion strengthened alloys (GlidCop AL-15).…”

Bond strength measurement for additively manufactured Inconel 718- GRCop84 copper alloy bimetallic joints

“…8. A commercially processed GRCop-84 has good ductility [34] compared to the LENS processed with brittle fracture behavior which could be attributed to rapid solidification during processing, resulting into fine grain structures. Heat treatment influences the strength of Inconel 718 and copper-chromium alloys through precipitation strengthening effect.…”

Copper-based alloys for structural high-heat-flux applications: a review of development, properties, and performance of Cu-rich Cu–Cr–Nb alloys

“…Regardless of fabrication, wrought GRCop-84 has generally good creep characteristics compared to the other high temperature Cu alloys studied by de Groh et al [78]. The step loaded and constant load creep results are compared in Table 7 based on the rate equations at a strain rate of 1 × 10 −6 s −1 .…”