Titanium alloys are metals which contain a mixture of titanium and other chemical elements. Such alloys have very high tensile strength and toughness (even at extreme temperatures). They are light in weight, have extraordinary corrosion resistance and the ability to withstand extreme temperatures.  The use of titanium alloys in airframes has continued to grow since the 1960's where it had its beginnings in military programs and ultimately moved into commercial aircraft.  It is one the most difficult material to machine. The challenges for metalworking fluids in titanium machining are examined by CIMCOOL in a technical report.