Cryogenic in-situ clamped beam testing of Sn96

Abstract

The deformation behavior of materials that exhibit a ductile to brittle transition have traditionally been characterized ex-situ and limited to bulk samples. Here, we use a unique experimental setup to perform in situ cryogenic mechanical testing of Sn 96 solder alloy in a clamped beam configuration at -142C, well below the alloy's DBTT. Electron backscattered diffraction analysis before and after the in situ experiments showed how deformation ahead of the crack tip is accommodated by the Sn matrix or intermetallic phase particles. Similar to behavior observed in pure Sn, within the Sn matrix of the Sn 96 alloy deformation twinning is the primary deformation mechanism below the DBTT. Similar to the twins previously observed in pure Sn, twinning behavior in the Sn matrix is consistent with the formation of the {301} and {101} twins in Sn. Within the intermetallic phase in Sn96, slip steps were observed that were not observed prior to bending.