An abnormal phenomenon of aluminium “pearl”-formation at the surface of Al-Al2O3 alloys was observed occasionally in quite different experimental conditions. In order to obtain more information, a series of hot-hardness and hot-compression tests was performed on SAP specimens. Qualitative correlations between the experimental variables and the experimental results are described; tentative explanations are related to Sherby's hypothesis of a continuous alumina network and to the presence of a non-oxidising atmosphere.