  We are concerned with the time decay rates of strong solutions to a
non-conservative compressible viscous two-phase fluid model in the whole space
R3. Compared to the previous related works, the main novelty of this paper lies
in the fact that it provides a general framework that can be used to extract
the optimal decay rates of the solution as well as its all-order spatial
derivatives from one-order to the highest-order, which are the same as those of
the heat equation. Furthermore, for well-chosen initial data, we also show the
lower bounds on the decay rates. Our methods mainly consist of Hodge
decomposition, low-frequency and high-frequency decomposition, delicate
spectral analysis and energy method based on finite induction.
