What is a Brittle Metal?

A brittle metal is metal that will fracture or break easily under stress.  For metal to be considered brittle, it has to break into separate pieces.  Cold temperature, pressure, and other environmental conditions will play a role in when a metal becomes brittle.

Metal is not considered to be brittle if it can stretch and pull to deform it.  This would mean the metal is ductile or malleable.  You often see metal being put under high temperatures to accomplish the deformation of metal.   

Brittle Metals and Brittle Metalloids

Metalloids are considered to be the more brittle metals available.  These will often break easier than that of other metals located on the left side of the periodic table.  Metalloids have properties between that of metals and nonmetals, which can contribute to a more brittle nature.  

Examples of these brittle metalloids include; Boron, Silicon, Germanium, Arsenic, Antimony, and Tellurium.

There are many that do not want to consider metalloids in the same context as other metals in the periodic table.  However if you include them as a metal, they would be considered the more brittle metals. 

The most brittle metal on earth seems to be currently undefined.  There are many factors to consider outside that of just the metal element and its properties on the periodic table.  Some might say Beryllium is the most brittle metal on earth as its physical ductility is 0.00.

A study by Richard M. Christensen on physical ductility and other data can be found here-> ”Physical Ductility of the Elements” if you are interested in reading about it.  I am not sure if all the data in this study concludes that beryllium might be the least ductile metal, or most brittle metal, on our earth.  However, it would seem the data may suggest as much under typical environmental conditions.

The study sets a 1.00 as “Absolute Limit, Perfect Ductility” and 0.00 as “Absolute Limit, Total Brittleness”.  Gold is at a 0.93 meaning it is very ductile and not brittle.  Zinc is at a 0.30 making it fairly brittle on the scale. 

Chemically Weak Metals

Chemically weak metals are not necessarily the most brittle metals.  However, weak chemical bonds can result in the breaking of metals with more ease.  There are nine chemically weak metals that we can note; Beryllium, magnesium, aluminum, gallium, tin, lead, antimony, bismuth, and polonium.

Once again Beryllium does come to the front of being a potential for one of the most brittle metals if it also has a weak chemical bond.  More commonly known metals such as lead and tin are not considered to be as brittle, though they are listed as having a weak chemical bond.

Can stronger metals become brittle?

Metals can become brittle when their environment changes and impurities are present in its chemical bonds.  Cast iron becomes brittle due to carbon impurities within it.  Steel can become brittle when temperatures reach -20 F or lower.

The strength within the bond of the metal will generally determine how long it can keep from breaking under different environmental considerations.  Most metals are not generally brittle and require some sort of environmental factors to make them brittle.

Many metals on the periodic table will become more brittle with the decrease in temperature.  When metals are mixed to make stronger alloys such as austenitic stainless steel, breaking under extreme cold temperatures becomes more difficult.

When metals are mixed and heated then cooled, chemical bonds can become much stronger and make the resulting metal less brittle.

Conclusion on Brittle Metals

In my research for the most brittle metal or most brittle metals on earth, it would seem a decisive answer was not very outright or forthcoming.

To make any definitive conclusions one would have to assume some sort of “normal” environmental conditions, pressure, and temperature for each metal.  Whatever “normal” might mean (mid-day sunshine, at sea level, at 87 degrees F).

I can conclude that possibly beryllium, under normal conditions, is the most brittle metal on earth based on much of the data I have seen.  I really do like the “Physical Ductility of the Elements” study that may help to back that up.  Many do seem to say that zinc is the benchmark for a very brittle metal as it is not ductile in nature.  In many scientific conclusions what occurs in nature, is what you should go by.