Curbing Titanium’s Creeping Nature

The physics of a thin wire appears at first to be very simple: apply the Hooke’s law so long as the wire hasn’t broken. But as with all branches of physics, adding more details makes the algebra treatment more accurate but quite a lot more complicated. Concepts like stress and strain, Young Modulus, hysteresis, elastic limit and limit of proportionality come in and make the mathematics more difficult if you want a answer that is closer to the truth. I will be writing a page on elastics quite soon but today the main focus is the idea of “creep”. So long as wire has a weight on it, it will continue to extend. This creeping is almost imperceivable at first but as a greater load is added the rate of creep increases until the point where the wire extends, keeps on extending and snaps.

Alloys of titanium are favoured in many construction projects because of titanium’s high melting point, resistance to corrosion and good strength to weight ratio. The main reason why alloys are used almost exclusively is because all metals are softer when pure and so creep much more easily. Silicon is a very common additive and used in close to all titanium alloys to massively reduce creeping but too much would make the alloy brittle and prone to fracture. A study has recently looked into exactly what happens in the mixture to ensure this effect occurs. By performing calculations based on the geometry and the interaction energy between the silicon and metal atoms it was concluded a strong covalent bond could form in the metal lattice disrupting the sliding structure meaning the planes could no longer slide over each other with ease. Combined with the different bonding between a metal and a metalloid the result is a much harder substance with less creep but also easier to crack.


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