Titanium alloys are metals that contain a mixture of titanium and other chemical elements. These alloys have very high tensile strength and toughness even at extreme temperatures. They are lightweight, have exceptional corrosion resistance and the ability to withstand extreme temperatures. However, the high cost of both raw material and processing limits their use to military applications, aircraft, spacecraft, bicycles, medical devices, jewelery, connecting rods in some sports cars, and some special sports equipment and electronics.
Although pure titanium has commercially acceptable mechanical properties and is used in orthopedic and dental implants, titanium for most applications is alloyed with small amounts of aluminum and vanadium, 6% and 4%, respectively. This mixture has a solid solubility that varies with temperature, which allows aging. This heat treatment application allows a high strength product to be produced much more easily after the alloy has been finished and before use. Titanium alloys have excellent formability and can be easily welded.
Many alloys contain a small proportion of titanium, but since the alloys are generally categorized by the element that makes up the majority of the material, they are generally not considered "titanium alloys". Commercial (99.2%) titanium alloys have a final tensile strength of about 434 MPa. It is equal to lower alloy steels but less dense.
Titanium is 60% more dense than aluminum, but twice as strong as the most widely used 6061.
Titanium is a strong and light metal. It is stronger than low carbon steels, but 45% lighter. It is also twice as strong as weak aluminum alloys, but only about 60% heavier. Titanium has excellent corrosion resistance to seawater and is therefore used in propeller shafts, rigging and other parts of boats exposed to seawater. Titanium alloys are used in aircraft, missiles and rockets, where strength, low weight and resistance to high temperatures are important. It is also used for fractures and other biological implants in artificial joints, screws and plates, as titanium does not react in the human body. It is widely used in metal orthopedic joint and bone plate operations.