can't we have innumerable number of alloys wherein every mixture of every metal is tried?

Answer 1

That would not be practical. Adding gold or silver to make better railroad rails would not prove economical not to mention the use of platinum. That said, making alloys in the lab and testing them is expensive and time consuming. It is better to have a specific objective such as trying vanadium and making enough samples to determine how much vanadium, etc. is optimal for the given application. Economics often rules engineering including metallurgy.

Answer 2

alloy already comes in a wide range of tempers for strength and flexibility,I guess if you want to try adding less or more copper to the furnis anything is possible,eg some of the types we have are 5005,5251,5253,5083,6064 and the list goes on. Some are weldable and some arn't but with mixing certain types of metal they reject each other like the super cut alloy cannot be welded,well it can but makes a mess and leaves little strength in the final product so super cut is best to be machined by a plasma cutter to design things like pulleys and things like that.