The influence of some microstructural and test parameters on the tensile stress and ductility behaviour of a MA FeAl intermetallic

Trabajo presentado en el Materials Research Society Symposium: High Temperature Ordered Intermetallic Alloys IX, celebrado en Boston, MA (Estados Unidos), del 27 al 29 de noviembre de 2000This study examines the influence of microstructural parameters (grain and dispersoid size, vacancy content) and some test parameters (strain rate, protective oxide coatings, air and water vapour excluding films, and surface geometrical quality) on the tensile behaviour (yield stress, work hardening rate, tensile stress, ductility) of a mechanically-alloyed, fine-grained Fe-40Al intermetallic. Major changes of strength and ductility are obtained by changing grain size (1% and 10% for grain sizes of 100μm and lμm) and by avoiding premature stress/strain concentrators (ductility increased from 5% to 10% for imperfectly machined to prepolished samples). Ductility variations are interpreted using a slow-crack-propagation-to-instability model, where the roles of environment, surface state, deformation processes, and fracture mechanisms can be distinguished.Peer reviewe