Embodiments of the invention relate to polycrystalline diamond compacts (“PDCs”) comprising a preformed polycrystalline diamond (“PCD”) table including a thermally-stable region having a copper-containing material disposed interstitially between bonded diamond grains thereof, and methods of fabricating such PDCs. In an embodiment, a PDC includes a substrate, and a preformed PCD table having an interfacial surface bonded to the substrate and a generally opposing upper surface. The PCD table includes a plurality of diamond grains exhibiting diamond-to-diamond bonding therebetween and defining a plurality of interstitial regions. The preformed PCD table further includes a first region extending inwardly from the upper surface that includes a copper-containing material disposed therein and a second region extending inwardly from the interfacial surface that includes a nickel-containing material disposed therein.