Mechanical Behavior of Cu-10Ni-6Sn Spinodal Alloy
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MECHANICAL BEHAVIOR OF Cu-1ONi-6Sn SPINODAL ALLOY T. C. LEE, S. SHEKHAR, A. VILASSAKDANONT, AND K. N. SUBRAMANIAN Department of Metallurgy, Mechanics and Materials Science Michigan State University, East Lansing, MI 48824 U.S.A. ABSTRACT Experimental studies on deformation behavior of Cu-lONi-6Sn spinodal alloy specimens subjected to different aging treatments were carried out at various temperatures ranging from 77°K to 353°K, using a micro-tensile It was found that the total elongation was independent of aging device. Observed slip time as long as the modulated structure was coherent. distribution and activation energy obtained in these investigations are presented. Transmission electron microscopy of deformed specimens showed straight dislocations in as-quenched samples; they were curved and wavy in aged samples. Burgers vector analysis of the dislocations present in the deformed aged samples indicated that they were of mixed character. Preliminary theoretical results on the role of wave-squaring of the internal stress field on CRSS are also presented. INTRODUCTION The mechanism of age hardening in spinodally decomposed alloys has gained a substantial amount of interest in recent years [1-12]. Several theories have been proposed to explain this age-hardening behavior [13-17]. Different relationships between the yield strength and the modulation parameters such as amplitude (A) and wavelength (X) have been predicted by these theories. The main purpose of the present investigations is to carry out deformation studies so as to characterize the dislocation behavior in a modulated structure resulting from early stages of spinodal decomposition. Preliminary calculations of CRSS due to hardening as a result of square-waved internal stress field are also carried out. The Cu-1ONi-6Sn alloy was chosen for the present investigation on the basis of its cubic structure, the relative ease in controlling at desired stages of decomposition, and as well as on the basis of the availability of experimental data regarding modulation parameters (A, X) and mechanical behavior [1-3, 9-11]. EXPERIMENTAL PROCEDURE Specimens were solution treated at 1073°K for one minute and quenched in water. Aging heat treatments were carried out for different lengths of time at 623°K. As-quenched and aged secimens were deformed in uniaxial tension at different testing temperatures (77°K to 353°K). Although most of the specimens tested had a grain size of about 10 pm, few large-grained samples with grain sizes about 1 mm (grown by strain-annealing method) were also used during the present studies. Deformed as-quenched and aged specimens were prepared for transmission electron microscopy by using a two-step electro-polishing process. The first step produced concave regions in portion of interest in the specimen and the second step produced foils transparent to electrons.
Mat.
Res.
Soc.
Symp.
Proc. Vol.
21 (1984)
QElsevier
science Publishing Co.,
Inc.
578
RESULTS AND DISCUSSION Mechanical
Test Results
During the course of this study, the to
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