High Strength Copper-Nickel Alloys Made by Rapid Solidification Technology (RST)
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HIGH STRENGTH COPPER-NICKEL ALLOYS MADE BY RAPID SOLIDIFICATION TECHNOLOGY (RST) V. PANCHANATHAN Marko Materials, Inc. 144 Rangeway Road No. Billerica, MA 01862 ABSTRACT Rapid solidification technology (RST) has been shown to offer outstanding prospects of processing new cost-effective engineering materials with superior properties. There has as yet been only limited effort in the use of RST to synthesize new and improved copper-base alloys. A detailed investigation has been carried out to develop new coppernickel alloys by RST. These alloys find extensive use as condenser tubes, seamless tubes, etc. New alloy systems suitable for processing by RST have been identified. These systems are as follows: a) Cu-Ni-B b) Cu-Ni-Al-B c) Cu-Ni-Cr-B d) Cu-Ni-Al-Cr-B The preferred composition ranges and maximum attainable hardness for each system are given. It is of interest to note that the maximum hardness value2 attained for this system are around 500 Kg/mm which is much higher than the hardness of the conventional copper-nickel alloys. INTRODUCTION Rapid solidification technology (RST) offers outstanding prospects for processing new cost-effective engineering materials with superior properties. The advent of RST has catalyzed new ideas across the wide spectrum of alloy structures, properties, and performance. A number of useful new alloys and products have already emerged from this rapidly evolving field [1,2,3]. There have been many investigations leading to the development of new iron- and aluminum-base alloys [4,51. However, as yet, there have been limited efforts in the use of RST to synthesize new and improved copper-base alloys. Many copper-base alloys have high electrical conductivity, high thermal conductivity, good corrosion resistance, machinability, fatigue characteristics, etc. When it is desirable to improve certain of the basic properties, especially strength, and when such an improvement can be effected with the sacrifice of no other properties except those of limited significance in the intended application, alloying often solves the problem; many alloys such as bronze, brasses, and copper-nickel alloys Normally the highest strength value of have been developed. wrought copper alloys is 160 ksi, excepting Be-Cu, which has a Mat.
Res.
Soc. SYmp. Proc. Vol.
28 (1984) @Elsevier Science Publishing Co.,
Inc.
432
maximum strength of 215 ksi. One of the popular copper-base alloys is copper-nickel. Copper-nickel alloys containing 10 to 30 wt% of nickel find extensive application as condenser tubes, seamless tubes, and finned tubes, and as plates, sheets, strips, rolled bars, etc. These alloys have maximum ultimate tensile strengths of 45 to When used in condenser tubes, they have the lowest heat 90 ksi. transfer coefficient. However, copper-nickel is the preferred material for saltwater service at high velocity because of longer service [6]. NEW COPPER ALLOYS Marko has studied extensively different copper-base alloys and has developed new copper-nickel systems with exceptionally hiqh strength. Besides copper
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