In a world with modern day scientific capabilities, would it be at all possible to create an alloy with a combination of both iron and silver that is usable within weaponry such as knives or swords or arrowheads as well as within chains or restrains or in the building of smaller structures? It would need to be both strong and durable. Magic is available in the world, so physical limitations aren't neccessarily relevant.
I googled it, and the answer is yes, you can alloy them. Of course, that particular link is to an alloy which is very biased towards silver, so it would not be durable. Other alloys can be found. The alloy in that link is mostly iron, but was noticeably more corrosion resistant. This suggests that most anything you can do with iron can be done with an iron/silver alloy, simply by keeping the silver content low.
Of course, once you start pushing into the higher levels of durability, such as what you want from steel, it becomes harder. Needless to say, metallurgists spend a lot of time figuring out what works and what doesn't, so you are unlikely to find many alloys which perform better than the ones we actually use.
Note that for most combinations you don't even need to alloy them. Use the Damascus approach, just with different metals. So long as there is a temperature at which all the metals can be worked and none of them will react badly with the others (which shouldn't be a problem with iron/silver/gold) you can make items which work against any metal-vulnerable creature even if the metals will not actually alloy.
Not just vamps, leaning towards demons and fallen ones. I too am looking to find an alloy for sword, knives and tips I was figuring on an electrum alloy (maybe 1-2 ounces needed... small amount), mixed with iron and charcoal............ theoretically, it should bear a durable blade, made of electrum-steel, folded over and over Damascus style.... for those who do not know, electrum is an alloy made with equal parts of pure gold and pure silver.... Sterling works too, that 7.5% copper difference just helps to strengthen it. Perfect blade for demons, vamps. Lychens.... you get the drift