Phase selection and nano-mechanical properties of intermetallic compounds in directionally solidified Cu-68at.%Sn peritectic alloy

In this work, directional solidification method was used to investigate the growth characteristics of intermetallic compounds whose solubilities are narrow during solidification of Cu-68at.%Sn alloys (L + Cu3Sn -> Cu6Sn5). It is found that the transition of the leading phase occurs during solidification at the intermediate growth velocities (5, 10 and 20 mu m/s). By the application of the Interface Response Function (IRF), the calculated velocity range for the transition from the primary phase to the peritectic phase is 2.1-33.4 mu m/s. Moreover, the phase transition of intermetallic compounds Cu3Sn and Cu6Sn5 does not initiates from the initial growth interface, and the distance required for phase transition to occur is found to increase with increasing growth velocity. The measurement of the hardness and Young's modulus was accomplished by the continuous stiffness measurement (CSM) technique during nanoindentation. The elastic modulus is nearly constant while the hardness increases with increasing growth velocity. In summary, the hardness of Cu3Sn phase is lower than that of Cu6Sn5 phase but Young's modulus shows reverse trend. In addition, multiple pop-in events are observed on the load-displacement curves of Cu6Sn5 phase at a strain rate of 0.1s(-1). (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

In this study, directional solidification method was used to investigate the growth characteristics of intermetallic compounds in Cu-68at.%Sn alloys. The research found that growth velocity affects the transition of primary phase, and conclusions about phase transition velocity and properties were obtained through the Interface Response Function and hardness testing.