Why are the properties of alloys gnerally superior to their constituent components?

Question

In most cases, not all, mixing metals forms eutectics (sometimes called eutectic mixtures). These eutectic mixtures are the combination of the elements that form the lowest melting point of the system and as such they may have different chemical sturctures, different corrosion resistance, strength, etc. Here is a site that tells a little about eutectics. Scroll to near the end of the page where the article talks about the varying properties as a result of forming alloys.
http://en.wikipedia.org/wiki/Eutectic