Ti diffuses through Au very quickly even at room temp and in minutes to
seconds at >150 C.  The Ti then oxidizes on the surface and coats the Au with a
TiOx layer.  Cr is even worse than Ti.   Virtually all metals will interdiffuse
to
some extent, it's just that Au is a really nasty actor in this case.  Pt is much
better
if you can use it.  There was a lot of work with interdiffusion of metals by
Bell
labs in the 1970's--mostly for their Au beam lead process.  You can search these
and more recent papers out in the literature (If memory serves me correctly Bell
labs came up with a PtxTiy alloy diffusion barrier---I think of the ratio of
3:1)).
However, there better ones available, but you need to search the literature.

-s-