Evidence of two-length-scale kinetics of R-phase transformation by high-energy X-ray diffraction

The cubic-to-rhombohedral (C-R) phase transition in an AuCd shape memory alloy was investigated by in situ high-energy X-ray diffraction. We present the first direct experimental evidence of two-length-scale phase transition kinetics in this alloy system. It was further found that aging in the R-phase leads to two-way memory “loss”, characterized by the reselection of new variants. We attributed this two-way memory “loss” to the internal stresses caused by the defects formed in the off-equilibrium state of the studied AuCd system.