Both #"copper"# and #"tin"# as the pure metals are relatively soft, and do not hold an edge. As an alloy, as #"BRONZE"#, tools made from the mixture are hard, and hold an excellent edge. Most of the metals we use are alloys.
#"Steel"# is another good example, an alloy that contains up to 1.5% carbon, and its modern usage is ubiquitous in tools and structures. #"Brass"# is an alloy of #"copper"# and #"zinc"#. Other than its main purpose (which of course is to make musical instruments!), #"brass"# is used for gas fittings in that you cannot make a spark from hitting brass metal together (sparks in gas lines could be disastrous; why?).
#"Duraluminum"# is a mixed alloy of #"aluminum"#, #"copper"#, #"manganese"#, and #"magnesium"#, and being lightweight (because of the #"aluminum content"#), is used for manufacture of parts for aircraft.
There is usually a specific alloy to deal with a specific purpose. These alloys are developed, and purpose chosen by metallurgists to fill a particular niche.
