Effect of Homogenization on the Indentation Creep
of Cast Lead-Free Sn-5%Sb Solder Alloy |
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Authors: | R Mahmudi A R Geranmayeh M Allami M Bakherad |
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Affiliation: | (1) School of Metallurgical and Materials Engineering, Faculty of Engineering, University of Tehran, Tehran, Iran;(2) Department of Mechanical Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran |
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Abstract: | Creep behavior of cast lead-free Sn-5%Sb solder in unhomogenized and homogenized conditions was investigated by long time
Vickers indentation testing under a constant load of 15 N and at temperatures in the range 321–405 K. Based on the steady-state
power law creep relationship, the stress exponents were found for both conditions of the material. The creep behavior in the
unhomogenized condition can be divided into two stress regimes, with a change from the low-stress regime to the high-stress
regime occurring around 11.7 × 10−4 < (H
V
/E) < 18 × 10−4. The low stress regime activation energy of 54.2 kJ mol−1, which is close to 61.2 kJ mol−1 for dislocation pipe diffusion in the Sn, and stress exponents in the range 5.0–3.5 suggest that the operative creep mechanism
is dislocation viscous glide. This behavior is in contrast to the high stress regime in which the average values of n = 11.5 and Q = 112.1 kJ mol−1 imply that dislocation creep is the dominant deformation mechanism. Homogenization of the cast material resulted in a rather
coarse recrystallized microstructure with stress exponents in the range 12.5–5.7 and activation energy of 64.0 kJ mol−1 over the whole ranges of temperature and stress studied, which are indicative of a dislocation creep mechanism. |
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Keywords: | Indentation creep lead-free solder hardness Sn-Sb alloy |
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