Depending on what you are trying to do, you aren't likely to find much information around on nitinol. Most of the actual formulations are either proprietary or well guarded. Since the percentages of the constituents as well as any processing completely changes the properties of the material, any material data you get will probably not really work if you are trying any sort of FEA analysis. If you are just looking for density and weight calculations in SW, then matweb should be sufficient.