Combined Recrystallization and Precipitation in a Cu-9Ni-6Sn Alloy
- PDF / 4,662,941 Bytes
- 9 Pages / 594 x 774 pts Page_size
- 59 Downloads / 265 Views
I.
INTRODUCTION
HIGH-strength Cu-Ni-Sn alloys produced by thermomechanical processing are currently being considered as possible substitutes for Cu-Be alloys in the manufacture of connectors, spring components, and so forth, in the electronic industries. 1 These alloys possess extensive agehardening capacities. Investigations have shown that proper manipulation of composition, amount of prior cold-work, aging time, and temperature in this system of alloys may yield material with very satisfactory combinations of yield limit and fracture ductility. A particular alloy composition, namely, Cu-9Ni-6Sn (wt pct) has been subjected to extensive investigation with a view to finding out its aging behavior after prior cold-work. 1'2Broadly speaking, this particular alloy, without prior cold-work, shows the following three stages of decomposition on aging: 3 (i) formation of a spinodal decomposition product, (ii) formation of an ordered phase, and (iii) discontinuous precipitation at a later stage. In the prior cold-worked material the first stage may be completely suppressed,3'4 although contradictory opinion has been expressed by others. 1 Again, recent work by Spooner et al 5 on the first stage of decomposition of a prior cold-worked Cu-15Ni-6Sn alloy using X-ray diffraction technique has demonstrated the existence of spinodal decomposition in this alloy. It is quite clear that the structural changes occurring during the aging of the deformed alloy will become more complicated because Of the interaction between the normal precipitation process and recrystallization. These two reactions may be sequential in nature or may be combined. In the present investigation an attempt has been made to find out the interrelationship between these two types of reactions which take place when the highly deformed alloy (95 pct cold-worked) is aged at two different temperatures, namely, 350 ~ and 600 ~ for variouslengths of time. For this R.K. RAY is Assistant Professor in the Department of Metallurgical Engineering, Indian Institute of Technology, Kanpur-208016 India. At present he is Alexander yon Humboldt Fellow, Institut fiir Allgemeine MetaUkunde und Metallphysik, R. W. T. H., 5100 Aachen, West Germany. S. CHANDRA NARAYANAN was formerly M. Tech Student, Department of Metallurgical Engineering, Indian Institute of Technology, Kanpur-208016 India. Manuscript submitted October 15, 1980. METALLURGICAL TRANSACTIONS A
9
purpose extensive electron microscopy and texture studies have been carried out.
II.
EXPERIMENTAL PROCEDURE
The alloy was prepared by induction melting of high purity Cu, Ni, and, Sn in an argon atmosphere. The as-cast alloy was homogenized at 825 ~ for 50 hours in a hydrogen atmosphere. The alloy was chemically analyzed, and it was found to have the following composition: Ni 8.90 wt pct, Sn 6.01 wt pct, and Cu balance. The alloy was cold rolled by an amount 95 pct in a two-high laboratory rolling mill, using paraffin oil as a lubricant. The cold-rolled specimens were heat treated in appropriate salt baths kept at 350
Data Loading...
