Improved functional stability of a coarse-grained Ti-50.8 at.% Ni shape memory alloy achieved by precipitation on dislocation networks

In this work, a new process is developed to improve the functional stability of Ni-rich NiTi alloys. Repetitive temperature- and stress-induced phase transformation is first conducted to generate dislocation networks in the grain interior. Dislocations serve as nucleation sites for Ni₄Ti₃ nanoprecipitates, which are formed after subsequent low-temperature (523 K) aging. With the presence of dislocations, a homogeneous distribution of nanoprecipitates in the grains is expected, enhancing the strength of the NiTi matrix and resisting plastic deformation during the martensitic transformation. As a result, an improved functional stability of NiTi alloys is achieved. ispartof: Scripta Materialia vol:163 pages:57-61 status: published