The low-temperature embrittlement of β-Sn poses a critical reliability challenge for Sn-based solders in cryogenic electronics. In this work, a comparative investigation was conducted by quasi-in-situ EBSD at 77 K and 293 K to elucidate the deformation mechanisms accounting for the ductile-to-brittle transition of β-Sn. It is found that the deformation mechanisms shift from dislocation-dominated to twinning-dominated as the temperature decreases. Dynamic recovery and continuous dynamic recrystallization were suppressed at 77 K, while discontinuous dynamic recrystallization occurred around the crack propagation path. The intergranular fracture at cryogenic temperature could be attributed to the failure of twin-twin transmission across grain boundaries. Molecular dynamics simulations further verified that the twin-twin transmission could accommodate the local strain, correlating its failure with the intergranular cracking. These findings offer new insights into the cryogenic brittleness of β-Sn, helping design Sn-based solders with enhanced cryogenic reliability.
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