Hafnium is a chemical element with symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals.
H 7915 (OTTO) Hafnium, dia.3 x 3 mm, 99.9% Cas 7440-58-6 - used in alloys with iron, titanium, niobium, tantalum, and other metals & as an alloy used for liquid rocket thruster nozzles.