Influence of compound twinning on Young's moduli in NiTi martensite

Abstract

NiTi shape memory alloy has been widely used in many engineering applications (e.g. mechatronic devices, medical tools, seismic sensors etc.). In this work, the Young's moduli of twinned NiTi martensite in selected crystallographic directions are calculated from first principles and ompared with previous data for perfect (untwinned) NiTi structure. The obtained results show that the selected twinning mode does not have a significant influence on the Young's moduli and, thus, their reduction observed in some experiments is probably caused by changes in martensitic microstructure (arrangement of twinning variants).NiTi shape memory alloy has been widely used in many engineering applications (e.g. mechatronic devices, medical tools, seismic sensors etc.). In this work, the Young's moduli of twinned NiTi martensite in selected crystallographic directions are calculated from first principles and ompared with previous data for perfect (untwinned) NiTi structure. The obtained results show that the selected twinning mode does not have a significant influence on the Young's moduli and, thus, their reduction observed in some experiments is probably caused by changes in martensitic microstructure (arrangement of twinning variants).