Solidification of Ni-Ti Shape Memory Alloy: Modeling and Simulation

The shape memory alloys have been used in the most different sectors such as aerospace, automotive and biomedical due to their ability to return to their original shape when subjected to high temperatures. Modeling and numerical simulation have become great allies in engineering due to the possibility of solving complex problems, especially in cases where experimental research is limited. In the present study, a two-dimensional mathematical model was developed to describe the solidification process of a Ni-Ti alloy in stainless steel metal mold sand confined. It was considered the flow of a refrigerant fluid (air) in the top of the mold. The energy conservation equation, including the phase change term, was discretized using finite volume method (FVM) and a fully implicit formulation. Results of the Ni-Ti alloy and mold temperature distributions over time are presented and analyzed. It was verified that results are independent of the mesh size and time step. The last point to be solidified is located at the top left corner of the study domain and the temperature distribution over time proved to be satisfactory for the absence of internal defects, such as voids, cracks, residual stresses and macro segregation.