Off world would help, no atmosphere on the moon for instance makes for less deterioration, and a cave system would shield it from radiation.

On earth clay tablets have done a great job : we have tablets 6000 years old, so we know that works. That’s 60% of 10k already. Titanium seems expensive and might be melted down in time of need, like bronze has been often in the past. Clay tablets survived partly because it’s a ‘worthless’ material.