Study of the precipitation in MgO.3.5 Al2O3 during creep experiments

The influence of stress on the planes of precipitation of α-Al 2O3 in MgO.3.5 Al2O3 single crystals is studied at 1 220 °C and 1 250 °C for three orientations of the compression axis. We find that the planes of precipitation are the { 111 } planes which have a maximum normal stress. An activation energy, as measured by temperature jumps, is found ranging from 3 to 3.5 eV.L'influence d'une contrainte sur les plans de précipitation de l'alumine α dans des monocristaux de spinelle MgO.3,5 Al2O3 a été étudiée à 1 220 °C et 1 250 °C. On trouve que les plans de précipitation sont les plans { 111 } de contrainte normale maximum. L'énergie d'activation, mesurée par sauts de température, varie de 3 à 3,5 eV