When saw the title,you may have known that fresh water m,must be the first.Yes,and then, Hank’s solution, sea water?A research published by Scientific Research Publishing gave you the answer by 4 shape memory alloys of Cu-Zn-Ni:
Four shape memory alloys of Cu-Zn-Ni, in the range of 35-55 wt% of Cu, 43-60 wt% Zn and 2-9 wt% Ni, were prepared by ingot metallurgy route in an induction furnace under an inert atmosphere. The shape memory effect was tested by bend test. The alloys were further tested for its corrosion behavior in fresh water, Hank’s solution and sea water. From the results it was observed that the alloys exhibit high corrosion resistance in fresh water when compared to Hank’s solution and sea water. And it was also observed that the alloys exhibit better corrosion resistance in Hank’s solution than in sea water.
(source:SCIRP/ Minerals and Materials Characterization and Engineering)