Mechanical fatigue of Sn-rich Pb-free solder alloys |
| |
Authors: | J K Shang Q L Zeng L Zhang Q S Zhu |
| |
Affiliation: | (1) Department of Materials Science and Engineering, University of Illinois,Urbana-Champaign, Urbana, IL 61801, USA;(2) Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 110016 Shenyang, China |
| |
Abstract: | Recent fatigue studies of Sn-rich Pb-free solder alloys are reviewed to provide an overview of the current understanding of
cyclic deformation, cyclic softening, fatigue crack initiation, fatigue crack growth, and fatigue life behavior in these alloys.
Because of their low melting temperatures, these alloys demonstrated extensive cyclic creep deformation at room temperature.
Limited amount of data have shown that the cyclic creep rate is strongly dependent on stress amplitude, peak stress, stress
ratio and cyclic frequency. At constant cyclic strain amplitudes, most Sn-rich alloys exhibit cycle-dependent and cyclic softening.
The softening is more pronounced at larger strain amplitudes and higher temperatures, and in fine grain structures. Characteristic
of these alloys, fatigue cracks tend to initiate at grain and phase boundaries very early in the fatigue life, involving considerable
amount of grain boundary cavitation and sliding. The growth of fatigue cracks in these alloys may follow both transgranular
and intergranular paths, depending on the stress ratio and frequency of the cyclic loading. At low stress ratios and high
frequencies, fatigue crack growth rate correlates well with the range of stress intensities or J-integrals but the time-dependent C* integral provides a better correlation with the crack velocity at high stress ratios and low frequencies. The fatigue life
of the alloys is a strong function of the strain amplitude, cyclic frequency, temperature, and microstructure. While a few
sets of fatigue life data are available, these data, when analyzed in terms of the Coffin–Mason equation, showed large variations,
with the fatigue ductility exponent ranging from −0.43 to −1.14 and the fatigue ductility from 0.04 to 20.9. Several approaches
have been suggested to explain the differences in the fatigue life behavior, including revision of the Coffin–Mason analysis
and use of alternative fatigue life models. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|