This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
William Justin Kroll, a Luxembourg-born metallurgist, solved titanium's century and a half old production problem in 1940 with a process that still bears his name and still dominates titanium production today. The Kroll process reduces titanium tetrachloride with magnesium inside an inert atmosphere, keeping the molten metal away from the oxygen, nitrogen and carbon it reacts with so violently, and that inert-atmosphere requirement is exactly why titanium remains difficult and costly to work compared with steel or aluminum even now. What that cost buys is a short list of properties nothing else quite matches at once: a strength-to-weight ratio that equals many steels at roughly half the density, a tenacious oxide film that gives it exceptional corrosion resistance, and a biocompatibility that makes it the standard material for surgical implants. Aerospace and biomedical engineering ended up sharing the same metal for almost opposite reasons, one needing strength without weight thirty thousand feet up and the other needing a material the human body will not reject, and both are still paying the Kroll process's own production cost for the privilege.