A process of converting an outer layer of an object made of a refractory metal, such as titanium, into a carbide of the refractory metal. A molten metal, such as molten lithium, is placed adjacent the outer surface of the object. The lithium does not react with the titanium, nor is it soluble within the titanium to any significant extent at the temperatures involved. The molten lithium contains elemental carbon, that is, free carbon atoms. At high temperature, the carbon diffuses into the titanium, and reacts with titanium atoms to form titanium carbide in an outer layer. Significantly, no other atoms are present, such as hydrogen or oxygen, which can cause problems, because they are blocked by the molten lithium.

In one or more embodiments, a shielding device is provided to shield a bore of a shaft against surface treatment, the shielding device including a sleeve to be at least partially received within the bore, the sleeve defining on its side wall a through-aperture and being of a first cross-sectional dimension when the through-aperture is at a rest position, and a pin to be at least partially received within the sleeve, the sleeve being of a second cross-sectional dimension greater than the first cross-sectional dimension when the through-aperture is at an expanded position with the pin being at least partially received within the sleeve.

Disclosed herein is a method for treating an article made of self-passivating metal including applying reagent to a surface portion of the article and applying laser light to the surface portion of the article to chemically activate the reagent, wherein the chemical activating of the reagent treats the surface portion for modification of one or more properties.