Abstract
Zirconium metal was heated in nitrogen, oxygen, and air at temperatures ranging from 425 to 1300 C. Observations were made on the gain in weight, micro‐ and macrohardness, and metallographic structures. Nitrogen diffuses into zirconium at a much slower rate than oxygen. A marked increase in penetration of both gases was found near 900 C, and this is evidently associated with the allotropic transformation from hexagonal, to cubic form. Practical limits for the heating of zirconium in air, oxygen and nitrogen are given and the possibilities of producing hard surface coatings are discussed.