You wouldn’t use tungsten to ‘salt’ the bars. To much of a pain to work with. You can’t pour molten tungsten into hollowed out gold bars because it would melt the hollowed out gold bar. Melting point of tungsten is 6192°F while gold is 1947°F. Machining tungsten to shape is also a pain. It is a tough metal.. so tough that it is used as the cutting bit in metal machining equipment.

If you are going to fill the bars, you would probably use a combination of lead and aluminum (621°F, 3632°F) respectively to get the weight right (aluminum centered within lead, centered within gold). Hollow out gold bar, suspend small aluminum bar within hollowed out segment and fill remainder with lead.