R6suml.-Une ltude thermique de la transition hexagonale compactcubique 1 faces centrdes de 4~e a ltd effectude depuis le voisinage du point triple jusqu's environ 3,7 kbar. La transition prlsente un cycle d'hystlrgsis de tempdrature dans toute la rlgion. Le caractsre ggndral de la transition suggzre une transformation martensitique. Des mesures de chaleur latente montrent que la transformation est partielle au-dessus de 16 K. Abstract.-The transition hcpfcc 4~e was studied thermally from the

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... inity of the triple point to about 3.7 kbar. It was found that the transition shows temperature hysteresis over the whole range. The general character of the transition suggests a martensitic transformation. Latent heat measurements show that above 16 K only partial transformation takes place. The transition hcpfcc 4~e /I/ was studied