The β/α phase transformation in zirconium and certain zirconium based alloys

Zirconium and zirconium based alloys transform on cooling from the high-temperature body centered cubic structure (β-phase) to the low-temperature hexagonal close packed structure (α-phase) and on heating the reverse transformation takes place. This transformation has considerable fundamental and practical interest since it is the basis of heat treatable zirconium alloys. Significant controversy has arisen regarding its nature, which has been considered either massive, bainitic or martensitic. The present work has been carried out in order to investigate the effect of continuous cooling rates and alloying additions on the kinetics and crystallography of the transformation, and on the morphology, substructure and strength of the transformation products. (author)