Statistics for The deformation behaviour of a series of alloys containing from 32 to 52 at.-%Al and containing various proportions of ?<inf>2</inf> and ? has been studied through compression tests at room temperature. The results showed that strain hardening tendency increases with increasing amount of lamellar constituent in the two phase alloys, which could be attributed to increased slip activity in these alloys as compared with single phase ?<inf>2</inf> or ? alloys. It is found that, in the two phase alloys, microcrack formation occurs by the mechanism of microvoid formation due to decohesion of the ?<inf>2</inf>/? interface and the coalescence of these microvoids. © 1992 The Institute of Materials.