Embodiments relate to polycrystalline diamond compacts (“PDCs”) including a polycrystalline diamond (“PCD”) table in which a metal-solvent catalyst is alloyed with at least one alloying element to improve thermal stability of the PCD table. In an embodiment, a PDC includes a substrate and a PCD table bonded to the substrate. The PCD table includes diamond grains defining interstitial regions. The PCD table includes an alloy comprising at least one Group VIII metal and at least one metallic alloying element that lowers a temperature at which melting of the at least one Group VIII metal begins. The alloy includes one or more solid solution phases comprising the at least one Group VIII metal and the at least one metallic alloying element and one or more intermediate compounds comprising the at least one Group VIII metal and the at least one metallic alloying element.