Case hardened component of titanium

A method of producing a case hardened component of a titanium alloy, the method comprising the steps of:

• providing a component of a titanium alloy,
• placing the component in a reactive atmosphere comprising a carbon providing gaseous species at a partial pressure of at least 10−5 bar, the carbon providing gaseous species containing carbon and oxygen, and which reactive atmosphere does not comprise a hydrogen containing species,
• heating the component in an inert atmosphere or the reactive atmosphere to a dissolution temperature TD of at least 800° C.,
• maintaining the component in the reactive atmosphere at TD for a reactive duration of at least 30 min to provide the component with a diffusion zone comprising carbon and oxygen in solid solution and having a distinct phase of a carbo-oxide compound having the composition TiOxC1-x, wherein x is a number in the range of 0.01 to 0.99, which diffusion zone has a microhardness of at least 800 HV0.025 and which carbo-oxide compound has a microhardness of at least 1200 HV0.025, the diffusion zone having a thickness of at least 10 μm,
• cooling the component from TD to ambient temperature.

A method of oxidising a component of a Group IV metal, the method comprising the steps of:

• providing a component of a Group IV metal,
• placing the component in an oxidising atmosphere comprising an oxidising gaseous species selected from the list consisting of CO2, mixtures of CO and CO2, H2O and mixtures of H2O and H2, or mixtures thereof, wherein the oxidising gaseous species is selected to provide a partial pressure of O2 of less than 0.1 bar,
• heating the component in an inert atmosphere or the oxidising atmosphere to an oxidising temperature TOx of at least 600° C.,
• maintaining the component in the oxidising atmosphere at TOx for a reactive duration of at least 5 min to dissolve oxygen in the component,
• cooling the component from TOx to ambient temperature.