Contribution à l'étude de la transformation allotropique du cobalt

✍ Scribed by A. Lanners; R. Breckpot

• Publisher: Wiley (John Wiley & Sons)
• Year: 2010
• Weight: 705 KB
• Volume: 63
• Category: Article
• ISSN: 0037-9646
• DOI: 10.1002/bscb.19540630502

✦ Synopsis

Abstract

The allotropic transformation of cobalt has been followed with a direct reading X‐ray spectrometer. The α→β transition occurs stepwise between 400° and 500° C, each increase in temperature in the given interval giving rise to the practically instantaneous formation of a new amount of β. The reverse transition occurs similarly but over a much wider temperature range and is not complete even far below 0° C.

The proportion of β remaining at room temperature is dependent on the density of lattice defects as measured by the broadening of definite α lines. This proportion can be increased to 90% by severe deformation followed by heat treatment, below 500°. Deformation after heat treatment suppresses totally the β phase. Heat treatment of short duration in the 500° ‐ 1480° C region tends to restore the lattice order, decreasing at the same time the proportion of β, retained in the cold, to some 35%.