Categories of Titanium Alloys - Alpha alloys contain neutral alloying elements like tin or alpha stabilizers like aluminum or oxygen. Examples include Ti-5Al-2Sn-ELI and Ti-8Al-1Mo-1V. - Near-alpha alloys contain a small amount of ductile beta-phase and are alloyed with beta phase stabilizers like molybdenum, silicon, or vanadium. Examples include Ti-6Al-2Sn-4Zr-2Mo and Ti-5Al-5Sn-2Zr-2Mo. - Alpha and beta alloys are metastable and include a combination of alpha and beta stabilizers. They can be heat treated. Examples include Ti-6Al-4V and Ti-6Al-6V-2Sn. - Beta and near beta alloys are metastable and contain sufficient beta stabilizers to maintain the beta phase. They can be solution treated and aged to improve strength. Examples include Ti-10V-2Fe-3Al and Ti-13V-11Cr-3Al.

Beta-Titanium - Beta titanium alloys exhibit the BCC allotropic form of titanium (beta phase) and contain elements like molybdenum, vanadium, niobium, tantalum, zirconium, manganese, iron, chromium, cobalt, nickel, and copper. - Beta titanium alloys have excellent formability and can be easily welded. - Beta titanium alloys replaced stainless steel for certain uses in orthodontics due to their strength/modulus of elasticity ratios and reduced force per unit displacement. - Some beta titanium alloys can convert to hard and brittle hexagonal omega-titanium at cryogenic temperatures or under the influence of ionizing radiation.

Transition Temperature - Titanium has a hexagonal alpha phase at ambient temperature and pressure, which transforms to a body-centered cubic beta phase at about 890°C. - Alpha stabilizers raise the alpha-to-beta transition temperature, while beta stabilizers lower it. - Alpha stabilizers include aluminum, gallium, germanium, carbon, oxygen, and nitrogen. Beta stabilizers include molybdenum, vanadium, tantalum, niobium, manganese, iron, chromium, cobalt, nickel, copper, and silicon.

Properties of Titanium Alloys - Beta-phase titanium is more ductile, while alpha-phase is stronger yet less ductile. - Alpha-beta-phase titanium has mechanical properties in between both phases. - Titanium alloys may contain oxide precipitates, which offer some strength but decrease toughness and are not very responsive to heat treatment. - Titanium and its alloys have outstanding corrosion resistance to seawater and are used in boats, airplanes, missiles, rockets, and biological implants. - Titanium is stronger than low-carbon steels but 45% lighter, and twice as strong as weak aluminum alloys but only 60% heavier.

Applications - Titanium is commonly used in aerospace structures for its resistance to corrosion and heat. - Titanium alloys are stronger than aluminum alloys and lighter than steel. - Titanium alloys are extensively used in biomedical applications, such as orthopedic joint replacements. - Titanium alloys can be produced through various techniques, including CNC machining and powder metallurgy. - Solid freeform fabrication (3D printing) is emerging as a method for producing titanium alloy products. - Aerospace Structures - Titanium is chosen for aviation due to its corrosion resistance, heat resistance, and high strength-to-weight ratio. - Titanium alloys are used in aircraft structures, such as blades, discs, rings, airframes, and fasteners. - The aerospace industry accounts for a significant portion of titanium alloy usage. - Titanium alloys offer superior performance in aerospace applications compared to aluminum and steel. - Titanium alloys are able to withstand high temperatures and harsh environments in aviation. - Biomedical - Titanium alloys are extensively used in orthopedic joint replacements and bone plate surgeries. - Different production methods, such as CNC machining and powder metallurgy, are used to manufacture biomedical titanium products. - Wrought products have material loss during machining, while cast samples have limitations in further processing. - Traditional powder metallurgy methods are material efficient but may face challenges in achieving fully dense products. - Solid freeform fabrication (3D printing) is a promising technique for biomedical titanium products.