Dynamic impact behavior of Ni-rich and Ti-rich shape memory alloys

摘要

Stress vs. strain curves of two kinds of Ti-Ni shape memory alloys under dynamic compressive loading condition were obtained by the split Hopkinson pressure bar experiment. One is Ni-rich, 50.75Ni-49.25Ti (at%), alloy and the other is Ti-rich, 49.5Ni-50.5Ti (at%). The former exists as austenite phase to show superelastic behavior at the room temperature, and the latter is martensitic phase at the room temperature. The dynamic stress-strain curves were compared with quasi-static compressive test results. The Ni-rich specimen displayed a much higher stress level at the high strain rate than at the quasi-static test, but the Ti-rich specimen exhibited a stress level alike in the two types of tests. Temperature measurement on the surface of the impact specimens was carried out during the impact test. The temperature rising was about 3-5 ℃ in the considered test conditions.