| Autor: |
Cai, S., Schaffer, J. E., Shi, T., Gao, J., Kadeřávek, L. |
| Zdroj: |
Shape Memory and Superelasticity; 20240101, Issue: Preprints p1-13, 13p |
| Abstrakt: |
NiTiCu alloys with Cu-content up to 20 at.% were successfully made into fine wire with cold-drawn area reduction of 70%. These materials were heat treated and tested at different conditions to study phase transformation and constitutive behavior. It is found that: (1) At Cu-content less than 7.5 at.%, increasing Cu stabilizes the B2 austenite, suppresses R-phase, and slightly decreases B19’ transformation temperatures. At higher level, Cu suppresses B19’-phase, but promotes B19 martensitic phase. (2) Increasing Cu decreases thermal temperature hysteresis and lattice strains during phase transformation. (3) The effect of Cu on stress hysteresis depends on test conditions. A continuous increase in Cu does not guarantee a continuously decreased stress hysteresis. (4) Heat treatment affects Ti2(Ni,Cu)3precipitation. The highest phase transformation temperatures were obtained after annealing at ~ 600 °C. (5) The 102B19and 120B19martensite texture comes from the 111B2austenite texture after phase transformation through {111} and/or {011} martensite twins. These texture patterns explain the relatively short transformation strains and suggest potential for large improvement through processing-induced texture optimization. (6) The combined effects of Cu addition and cold work strengthening largely increase thermal cycling stabilities of NiTiCu alloys and make them promising candidates for actuator applications. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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