Gold and palladium are totally soluble in one another.
The primary use of gold / palladium alloys is in jewellery. However, gold / palladium alloys are also used in dentistry and they were used as spark plug electrodes, but the alloy has now been replaced by platinum.
The alloy is more commonly known as white gold and is an alternative to platinum. Gold / nickel alloys are also used as white gold. In both cases some other metals may be present in small amounts such as silver, zinc and copper.