Microstructure of NiTi shape memory alloy due to tension-compression cyclic deformation

摘要

Experimental results have shown that, during mechanical cycling under tension-compression load within±4/100 strains, the NiTi shape memory alloys is cyclic strain-hardened. The maximum stresses under both tension and compression increase with increasing number of cycles and tend to stabilize with further cycling. The present work is focused on the martensite microstructure developed as a result of mechanical cycling. TEM observations show that, before cycling, the martensite variants are well self- accommodated to each other with the <011> type II twinning as the main lattice invariant shear.