This NASA document (pages 62 onwards)[0] (1974) here gives a more in-depth description of NTO materials compatibility than the link above (1970)

Titanium is practically the only metal that can store NTO for long periods of time over a reasonably large temperature range. This does come at the expense of shock sensitivity (particularly after a soak/adsorb), but the industry has to use it anyway, while working to mitigate the shock problem.

[0] https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/197200...