Study on the compressive behavior of Ti–53.22 at%Ni alloy sheets after pre-compression and aging treatments

Three factors and three levels of orthogonal experiments were conducted to study the effects of pre-compression, aging temperature and aging time on the compressive behavior of Ti–53.22 at%Ni alloy sheets. Phase transformation temperatures and compressive behavior at room temperature were investigated. Range analysis of differential scanning calorimeter (DSC) curves shows that R-phase transformations are dependent on aging temperature, and there is no R-phase transformation after aging at 523 K, the R-phase transformation reliably occurs after aging at 673 K. A saw tooth shape on the stress–strain curves is observed and indicates the occurrence of martensitic transformation. Two kinds of martensitic transformation exist under the compression conditions. Higher compressibility can be achieved by pre-compression of 0.2%, and aging at 523 K results in better recovery.

► At least two kinds of martensitic transformations occurred during compression.
► Pre-compression is a dominant factor for compressibility of the sheet.
► Recovery of the NiTi sheet correlates closely with aging temperature.