There is some brand is using Niobium for making watch cases but is unusual. Why? Because niobium was not commercialized until 20th century. It was called columbium even some of us we remembered it with this name. I thought niobium belonged to the category of rare earth elements, so it was very expensive and very difficult to find. But I was wrong.
Niobium is relatively common with 33 number position among them. It is ductile and soft when is almost pure between 80-130 HV, similar like bronze. It is used in different alloys because it enhances the strength of them.
Maybe some of the most interesting features is its inert allergenic activity. Now it is very used in medical devices. As well is very used in jewelry because when niobium is anodized it is produced a wide variety of colours very nice.
At the end, niobium adquieres a bluish tinge when it is exposed to air long time. I would like to look at a niobium watchcase long time after being manufactured. Like patina bronze, niobium with bluish tinge should be very attractive for me and for customer. Morever, it is not so expensive like I thought.
Some of the propierties
Bulk Modulus 150 – 184 GPa
Compressive Strength * 75 – 105 MPa
Elongation 25 – 40 %
Elastic Limit 75 – 105 MPa
Endurance Limit * 65 – 105 MPa
Fracture Toughness * 90 – 120 MPa.m^1/2
Hardness – Vickers 80 – 160 HV
Loss Coefficient * 1.8e-3 – 2.7e-3
Modulus of Rupture * 75 – 105 MPa
Poisson’s Ratio 0.39 – 0.4
Shape Factor 30
Shear Modulus 34 – 40 GPa
Tensile Strength 170 – 205 MPa
Young’s Modulus 100 – 110 GPa